50278 + Interview Questions in Physics

1.	The electric field in a region is given by →E=(^3i−^4j) N/C. Find out the work done (in joule) in displacing a particle of charge 1C by 1 m along the line 4y = 3x + 9___
Answer» The electric field in a region is given by $\to E = (^3 i -^4 j)$ N/C. Find out the work done (in joule) in displacing a particle of charge 1C by 1 m along the line 4y = 3x + 9___

Discussion

2.	The time taken by a particle executing simple harmonic motion of time period T to move from the mean position to half the maximum displacement is
Answer» The time taken by a particle executing simple harmonic motion of time period T to move from the mean position to half the maximum displacement is

Discussion

3.	At what temperature will the rms speed of oxygen molecules becomes just sufficient to escape from the earth's atmosphere?(Given: Mass of oxygen molecule (m)=2.76×10−26 kg, Boltzmann constant i.e. kB=1.38×10−23JK−1)
Answer» At what temperature will the rms speed of oxygen molecules becomes just sufficient to escape from the earth's atmosphere?(Given: Mass of oxygen molecule $(m) = 2.76 \times 10^{- 26} k g$ , Boltzmann constant i.e. $k_{B} = 1.38 \times 10^{- 23} J K^{- 1}$ )

Discussion

4.	The dimensional formula for relative density is
Answer» The dimensional formula for relative density is

Discussion

5.	Figure (38-E23) shows a smooth pair of thick metallic rails connected across a battery of emf ε having a negligible internal resistance. A wire ab of length l and resistance r can slide smoothly on the rails. The entire system lies in .a horizontal plane and is immersed in a uniform vertical magnetic field B. At an instant t, the wire is given a small velocity u towards right. (a) Find the current in it at this instant. What is the direction of the current ? (b) What is the force acting on the wire at this instant ? (c) Show that after some time the wire ab will slide with a constant velocity. Find this velocity.
Answer» Figure (38-E23) shows a smooth pair of thick metallic rails connected across a battery of emf $ε$ having a negligible internal resistance. A wire ab of length l and resistance r can slide smoothly on the rails. The entire system lies in .a horizontal plane and is immersed in a uniform vertical magnetic field B. At an instant t, the wire is given a small velocity u towards right. (a) Find the current in it at this instant. What is the direction of the current ? (b) What is the force acting on the wire at this instant ? (c) Show that after some time the wire ab will slide with a constant velocity. Find this velocity.

5.

Figure (38-E23) shows a smooth pair of thick metallic rails connected across a battery of emf ε having a negligible internal resistance. A wire ab of length l and resistance r can slide smoothly on the rails. The entire system lies in .a horizontal plane and is immersed in a uniform vertical magnetic field B. At an instant t, the wire is given a small velocity u towards right. (a) Find the current in it at this instant. What is the direction of the current ? (b) What is the force acting on the wire at this instant ? (c) Show that after some time the wire ab will slide with a constant velocity. Find this velocity.

Answer»

Figure (38-E23) shows a smooth pair of thick metallic rails connected across a battery of emf $ε$ having a negligible internal resistance. A wire ab of length l and resistance r can slide smoothly on the rails. The entire system lies in .a horizontal plane and is immersed in a uniform vertical magnetic field B. At an instant t, the wire is given a small velocity u towards right. (a) Find the current in it at this instant. What is the direction of the current ? (b) What is the force acting on the wire at this instant ? (c) Show that after some time the wire ab will slide with a constant velocity. Find this velocity.

Discussion

6.	A block of mass m is placed on the floor of lift which is moving with velocity v=4t2, where t is time in second and velocity in m/s. Find the time at which normal force on the block is three times of its weight.
Answer» A block of mass $m$ is placed on the floor of lift which is moving with velocity $v = 4 t^{2}$ , where $t$ is time in second and velocity in $m/s$ . Find the time at which normal force on the block is three times of its weight.

Discussion

7.	Two bodies M and N of equal masses are suspended from two separate spring of the spring s constant k1 and k2 respectively. If the two bodies oscillate vertically such that their maximum velocities are equal, the ratio of the amplitude of vibration of M to that on N is
Answer» Two bodies M and N of equal masses are suspended from two separate spring of the spring s constant $k_{1}$ and $k_{2}$ respectively. If the two bodies oscillate vertically such that their maximum velocities are equal, the ratio of the amplitude of vibration of M to that on N is

Discussion

8.	ABCD is a square, O is the center of the square. −→F1, −→F2, −→F3 and −→F4 represent four forces acting along sides AB,BC,CA and AD respectively. If torque about O is zero then \|−→F2\| is
Answer» $A B C D$ is a square, $O$ is the center of the square. $_{1}$ , $_{2}$ , $_{3}$ and $_{4}$ represent four forces acting along sides $A B, B C, C A$ and $A D$ respectively. If torque about $O$ is zero then $\|_{2} \|$ is

Discussion

9.	Two particles are kept on a smooth surface and they move towards each other. If the position and velocities of the particles at t=0 is as shown in the figure. Then position of the center of mass at t=2 sec is
Answer» Two particles are kept on a smooth surface and they move towards each other. If the position and velocities of the particles at $t = 0$ is as shown in the figure. Then position of the center of mass at $t = 2 s e c$ is

9.

Two particles are kept on a smooth surface and they move towards each other. If the position and velocities of the particles at t=0 is as shown in the figure. Then position of the center of mass at t=2 sec is

Answer»

Two particles are kept on a smooth surface and they move towards each other. If the position and velocities of the particles at $t = 0$ is as shown in the figure. Then position of the center of mass at $t = 2 s e c$ is

Discussion

10.	A vessel whose bottom has a round hole with diameter 0.1 mm is filled with water. The maximum height up to which water can be filled without leakage is ............. cm (given surface tension =7.5×10−2Nm−1 and g=10ms−2
Answer» A vessel whose bottom has a round hole with diameter 0.1 mm is filled with water. The maximum height up to which water can be filled without leakage is ............. cm (given surface tension $= 7.5 \times 10^{- 2} N m^{- 1}$ and $g = 10 m s^{- 2}$

Discussion

11.	The value of which of the following quantities increases with increase in temperature for a conductor?
Answer» The value of which of the following quantities increases with increase in temperature for a conductor?

Discussion

12.	A proton, a deuteron and an α- particle having the same kinetic energy are moving in circular trajectories in a constant magnetic field. If rp, rd and rα denote respectively the radii of the trajectories of these particles, then
Answer» A proton, a deuteron and an $α$ - particle having the same kinetic energy are moving in circular trajectories in a constant magnetic field. If $r_{p}, r_{d}$ and $r_{α}$ denote respectively the radii of the trajectories of these particles, then

Discussion

13.	The electron beam in a colour TV is accelerated through 32 kV and then strikes the screen. What is the wavelength of the most energetic X-ray photon ?
Answer» The electron beam in a colour TV is accelerated through 32 kV and then strikes the screen. What is the wavelength of the most energetic X-ray photon ?

Discussion

14.	Figure shows a paddle wheel coupled to a mass of 12 kg through fixed frictionless pulleys. The paddle is immersed in a liquid of heat capacity 4200 J K−1 kept in an adiabatic container. Consider a time interval in which the 12 kg block falls slowly through 70 cm. (a) How much heat is given to the liquid ? (b) How much work is done on the liquid ? (c) Calculate the rise in the temperature of the liquid neglecting the heat capacity of the container and the paddle.
Answer» Figure shows a paddle wheel coupled to a mass of 12 kg through fixed frictionless pulleys. The paddle is immersed in a liquid of heat capacity $4200 J K^{- 1}$ kept in an adiabatic container. Consider a time interval in which the 12 kg block falls slowly through 70 cm. (a) How much heat is given to the liquid ? (b) How much work is done on the liquid ? (c) Calculate the rise in the temperature of the liquid neglecting the heat capacity of the container and the paddle.

14.

Figure shows a paddle wheel coupled to a mass of 12 kg through fixed frictionless pulleys. The paddle is immersed in a liquid of heat capacity 4200 J K−1 kept in an adiabatic container. Consider a time interval in which the 12 kg block falls slowly through 70 cm. (a) How much heat is given to the liquid ? (b) How much work is done on the liquid ? (c) Calculate the rise in the temperature of the liquid neglecting the heat capacity of the container and the paddle.

Answer»

Figure shows a paddle wheel coupled to a mass of 12 kg through fixed frictionless pulleys. The paddle is immersed in a liquid of heat capacity $4200 J K^{- 1}$ kept in an adiabatic container. Consider a time interval in which the 12 kg block falls slowly through 70 cm.

(a) How much heat is given to the liquid ?

(b) How much work is done on the liquid ?

(c) Calculate the rise in the temperature of the liquid neglecting the heat capacity of the container and the paddle.

Discussion

15.	Find the equivalent resistance of the networks shown in figure (32-E21) between the point a and b. figure (32-E21)
Answer» Find the equivalent resistance of the networks shown in figure (32-E21) between the point a and b. figure (32-E21)

15.

Find the equivalent resistance of the networks shown in figure (32-E21) between the point a and b. figure (32-E21)

Answer»

Find the equivalent resistance of the networks shown in figure (32-E21) between the point a and b.

figure (32-E21)

Discussion

16.	In LCR circuit, resonant frequency is 600 Hz and half power points are at 650 Hz and 550 Hz. The quality factor is
Answer» In LCR circuit, resonant frequency is $600 Hz$ and half power points are at $650$ Hz and $550 Hz$ . The quality factor is

Discussion

17.	In the figure pulley p1 is fixed and p2 is movable. If W1=W2=100 N, what is the angle (in degrees) AP2P1 when the system is in equilibrium? The pulleys are massless and frictionless
Answer» In the figure pulley $p_{1}$ is fixed and $p_{2}$ is movable. If $W_{1} = W_{2} = 100 N,$ what is the angle (in degrees) $A P_{2} P_{1}$ when the system is in equilibrium? The pulleys are massless and frictionless

Discussion

18.	The equation of a travelling sound wave is y =6.0 sin (600 -1.8 x) where y is measured in 10−5m, t in second and x in metre. (a) Find the ratio of the displacement amplitude of the particles to the wavelength of the wave. (b) Find the ratio of the velocity amplitude of the particles to the wave speed.
Answer» The equation of a travelling sound wave is y =6.0 sin (600 -1.8 x) where y is measured in $10^{- 5}$ m, t in second and x in metre. (a) Find the ratio of the displacement amplitude of the particles to the wavelength of the wave. (b) Find the ratio of the velocity amplitude of the particles to the wave speed.

Discussion

19.	The magnetic field B and the magnetic intensity H in a material are found to be 1.6 T and 1000 A m−1 respectively. Calculate the relative permeability μr and the susceptibility x of the material.
Answer» The magnetic field B and the magnetic intensity H in a material are found to be 1.6 T and 1000 A $m^{- 1}$ respectively. Calculate the relative permeability $μ_{r}$ and the susceptibility x of the material.

Discussion

20.	The area bounded by the line y=x+2 and x=−1 and x=1 is
Answer» The area bounded by the line $y = x + 2$ and $x = - 1$ and $x = 1$ is

Discussion

21.	A body builder exerts a force of 150 N against a bullworker and compresses it by 20 cm. Calculate the spring constant of the spring in the bullworker.
Answer» A body builder exerts a force of 150 N against a bullworker and compresses it by 20 cm. Calculate the spring constant of the spring in the bullworker.

Discussion

22.	The mass M of the hanging block in figure which will prevent the small block from slipping over the triangular block, if all the surfaces are frictionless and the strings and the pulleys are light is
Answer» The mass $M$ of the hanging block in figure which will prevent the small block from slipping over the triangular block, if all the surfaces are frictionless and the strings and the pulleys are light is

Discussion

23.	The wavelength of radiation emitted is λ0 when an electron jumps from the third to the second orbit of hydrogen atom. If the electron jumps from the fourth to the second orbit of the hydrogen atom, the wavelength of radiation emitted will be
Answer» The wavelength of radiation emitted is $λ_{0}$ when an electron jumps from the third to the second orbit of hydrogen atom. If the electron jumps from the fourth to the second orbit of the hydrogen atom, the wavelength of radiation emitted will be

Discussion

24.	Capacitors are charged and connected as shown in figure. If switch is closed at t=0, find work done by battery.
Answer» Capacitors are charged and connected as shown in figure. If switch is closed at $t = 0$ , find work done by battery.

Discussion

25.	A coil carries a current and experiences a torque due to a magnetic filed. The value of the torque is 80% of the maximum possible torque. The angle between the magnetic field and the normal to the plane of the coil is
Answer» A coil carries a current and experiences a torque due to a magnetic filed. The value of the torque is 80% of the maximum possible torque. The angle between the magnetic field and the normal to the plane of the coil is

Discussion

26.	A beam of white light is incident normally on a plane surface absorbing 70% of the light and reflecting the rest. If the incident beam carries 10 W of power, find the force exerted by it on the surface.
Answer» A beam of white light is incident normally on a plane surface absorbing 70 $%$ of the light and reflecting the rest. If the incident beam carries 10 W of power, find the force exerted by it on the surface.

Discussion

27.	A water tank has the slope of an inverted right circular cone with its axis vertical and vertex lowermost. Its semi-vertical angle is tan−1(0.5). Water is poured into it at a constant rate of 5 cubic metre per hour. Find the rate at which the level of the water is rising at the instant when the depth of water in the tank is 4 m. (π=227)
Answer» A water tank has the slope of an inverted right circular cone with its axis vertical and vertex lowermost. Its semi-vertical angle is ${tan}^{- 1} (0.5)$ . Water is poured into it at a constant rate of $5$ cubic metre per hour. Find the rate at which the level of the water is rising at the instant when the depth of water in the tank is $4 m .$ $(π = \frac{22}{7})$

Discussion

28.	A bat emits ultrasonic sound of frequency 1000 kHz in air. If the sound meets a water surface, what is the wavelength of (a) the reflected sound, (b) the transmitted sound? Speed of sound in air is 340ms−1 and in water 1486ms−1.
Answer» A bat emits ultrasonic sound of frequency 1000 kHz in air. If the sound meets a water surface, what is the wavelength of (a) the reflected sound, (b) the transmitted sound? Speed of sound in air is $340 m s^{- 1}$ and in water $1486 m s^{- 1}$ .

Discussion

29.	A block of mass m is kept over another block of mass M and the system rests on a horizontal surface. A constant horizontal force F acting on the lower block produces acceleration F2(m+M) in the system, the two blocks always move together. Find the work done by the force of friction on the smaller block by the bigger block during a displacement d of the system.
Answer» A block of mass m is kept over another block of mass $M$ and the system rests on a horizontal surface. A constant horizontal force $F$ acting on the lower block produces acceleration $\frac{F}{2 (m + M)}$ in the system, the two blocks always move together. Find the work done by the force of friction on the smaller block by the bigger block during a displacement d of the system.

29.

A block of mass m is kept over another block of mass M and the system rests on a horizontal surface. A constant horizontal force F acting on the lower block produces acceleration F2(m+M) in the system, the two blocks always move together. Find the work done by the force of friction on the smaller block by the bigger block during a displacement d of the system.

Answer»

A block of mass m is kept over another block of mass $M$ and the system rests on a horizontal surface. A constant horizontal force $F$ acting on the lower block produces acceleration $\frac{F}{2 (m + M)}$ in the system, the two blocks always move together. Find the work done by the force of friction on the smaller block by the bigger block during a displacement d of the system.

Discussion

30.	Plates of a parallel plate capacitor (C=6 nF) carries charge Q1=12 nC and Q2=6 nC, then energy stored in capacitor is
Answer» Plates of a parallel plate capacitor $(C = 6 n F)$ carries charge $Q_{1} = 12 n C$ and $Q_{2} = 6 n C$ , then energy stored in capacitor is

Discussion

31.	A particle tied to the end of a string oscillates along a circular arc in a vertical plane. The other end of the string is fixed at the centre of the circle. If the string has a breaking strength of twice the weight of the particle; (x) Find the maximum distance that the particle can cover in one cycle of oscillation. The length of the string is 50 cm. (y) Find the tension in the extreme position (z) Find the net acceleration of the particle at extreme (i) 2π3m (ii)mg4 (iii) g√23 (iv)mg2 (v)π3m (vi) g√32
Answer» A particle tied to the end of a string oscillates along a circular arc in a vertical plane. The other end of the string is fixed at the centre of the circle. If the string has a breaking strength of twice the weight of the particle; (x) Find the maximum distance that the particle can cover in one cycle of oscillation. The length of the string is 50 cm. (y) Find the tension in the extreme position (z) Find the net acceleration of the particle at extreme (i) $\frac{2 π}{3} m$ (ii) $\frac{m g}{4}$ (iii) $g \sqrt{\frac{2}{3}}$ (iv) $\frac{m g}{2}$ (v) $\frac{π}{3} m$ (vi) $g \sqrt{\frac{3}{2}}$

31.

A particle tied to the end of a string oscillates along a circular arc in a vertical plane. The other end of the string is fixed at the centre of the circle. If the string has a breaking strength of twice the weight of the particle; (x) Find the maximum distance that the particle can cover in one cycle of oscillation. The length of the string is 50 cm. (y) Find the tension in the extreme position (z) Find the net acceleration of the particle at extreme (i) 2π3m (ii)mg4 (iii) g√23 (iv)mg2 (v)π3m (vi) g√32

Answer»

A particle tied to the end of a string oscillates along a circular arc in a vertical plane. The other end of the string is fixed at the centre of the circle. If the string has a breaking strength of twice the weight of the particle; (x) Find the maximum distance that the particle can cover in one cycle of oscillation. The length of the string is 50 cm. (y) Find the tension in the extreme position (z) Find the net acceleration of the particle at extreme

(i) $\frac{2 π}{3} m$ (ii) $\frac{m g}{4}$ (iii) $g \sqrt{\frac{2}{3}}$ (iv) $\frac{m g}{2}$ (v) $\frac{π}{3} m$

(vi) $g \sqrt{\frac{3}{2}}$

Discussion

32.	Half of the rectangular plate shown in figure is made of a material of density p1 and the other half of density p2. The length of the plate is L. Locate the centre of mass of the plate.
Answer» Half of the rectangular plate shown in figure is made of a material of density $p_{1}$ and the other half of density $p_{2}$ . The length of the plate is $L$ . Locate the centre of mass of the plate.

Discussion

33.	Consider the figure. The charge appearing on C2 is
Answer» Consider the figure. The charge appearing on $C_{2}$ is

Discussion

34.	During an experiment, a signal from a spaceship reached the ground station in five minutes. What was the distance of the spaceship from the ground station? The signal travels at the speed of light, that is, 3×108ms−1
Answer» During an experiment, a signal from a spaceship reached the ground station in five minutes. What was the distance of the spaceship from the ground station? The signal travels at the speed of light, that is, $3 \times 10^{8} m s^{- 1}$

Discussion

35.	James Prescott Joule, after whom the unit of energy is named, wanted to prove that mechanical energy can be converted to thermal energy. To help him prove that,he created the setup as shown in the figure. 1kg of water is stored in an adiabatic container at 15∘C. A paddle connected to a mass of 15 kgs through massless and frictionless pulleys, is immersed into the water. At time t = 0s, the 15kg mass is allowed to fall. After 40s it was noticed that the mass had fallen by a height of 10 m and gained a velocity of 4 m/s. If Joule was successful in this experiment, what would be the temperature of the water at time t = 40s?
Answer» James Prescott Joule, after whom the unit of energy is named, wanted to prove that mechanical energy can be converted to thermal energy. To help him prove that,he created the setup as shown in the figure. 1kg of water is stored in an adiabatic container at $15^{\circ} C$ . A paddle connected to a mass of 15 kgs through massless and frictionless pulleys, is immersed into the water. At time t = 0s, the 15kg mass is allowed to fall. After 40s it was noticed that the mass had fallen by a height of 10 m and gained a velocity of 4 m/s. If Joule was successful in this experiment, what would be the temperature of the water at time t = 40s?

35.

James Prescott Joule, after whom the unit of energy is named, wanted to prove that mechanical energy can be converted to thermal energy. To help him prove that,he created the setup as shown in the figure. 1kg of water is stored in an adiabatic container at 15∘C. A paddle connected to a mass of 15 kgs through massless and frictionless pulleys, is immersed into the water. At time t = 0s, the 15kg mass is allowed to fall. After 40s it was noticed that the mass had fallen by a height of 10 m and gained a velocity of 4 m/s. If Joule was successful in this experiment, what would be the temperature of the water at time t = 40s?

Answer»

James Prescott Joule, after whom the unit of energy is named, wanted to prove that mechanical energy can be converted to thermal energy. To help him prove that,he created the setup as shown in the figure.

1kg of water is stored in an adiabatic container at $15^{\circ} C$ . A paddle connected to a mass of 15 kgs through massless and frictionless pulleys, is immersed into the water.

At time t = 0s, the 15kg mass is allowed to fall. After 40s it was noticed that the mass had fallen by a height of 10 m and gained a velocity of 4 m/s. If Joule was successful in this experiment, what would be the temperature of the water at time t = 40s?

Discussion

36.	The wave theory of light predicted that the stopping potential for a conductor in photoelectric effect, ______________ on increasing the frequency of light. Intensity is kept constant.
Answer» The wave theory of light predicted that the stopping potential for a conductor in photoelectric effect, ______________ on increasing the frequency of light. Intensity is kept constant.

Discussion

37.	The value of coefficient of volume expansion of glycerin is 5×10−4 ∘C−1. The fractional change in the density of glycerin for a rise of 40 ∘C in its temperature is
Answer» The value of coefficient of volume expansion of glycerin is $5 \times 10^{- 4} {^{\circ} C}^{- 1}$ . The fractional change in the density of glycerin for a rise of $40^{\circ} C$ in its temperature is

Discussion

38.	Calculate the change in internal energy of a gas kept in a rigid container when 100 J of heat is supplied to it.
Answer» Calculate the change in internal energy of a gas kept in a rigid container when 100 J of heat is supplied to it.

Discussion

39.	Find the angle between the vectors ^i−2^j+3^k and 3^i−2^j+^k
Answer» Find the angle between the vectors $^i - 2^j + 3^k$ and $3^i - 2^j +^k$

Discussion

40.	If velocity of a particle depends on time as v = t3+2√t. Then with what velocity is the particle moving at t = 4 sec and what is the displacement till then?
Answer» If velocity of a particle depends on time as v = $t^{3} + \frac{2}{\sqrt{t}}$ . Then with what velocity is the particle moving at t = 4 sec and what is the displacement till then?

Discussion

41.	What is the translational kinetic energy of a Helium molecule (He) at 1500 K?
Answer» What is the translational kinetic energy of a Helium molecule (He) at 1500 K?

Discussion

42.	An insulated chamber at a height h above the earth’s surface and maintained at 30∘C has a clock fitted with an uncompensated pendulum. The maker of the clock for the chamber mistakenly designs it to maintain correct time at 20∘C at that height. It is found that if the chamber were brought to earth’s surface the clock in it would click correct time at 30∘C. The coefficient of linear expansion of the material of pendulum is (earth’s radius is R):
Answer» An insulated chamber at a height $h$ above the earth’s surface and maintained at $30^{\circ} C$ has a clock fitted with an uncompensated pendulum. The maker of the clock for the chamber mistakenly designs it to maintain correct time at $20^{\circ} C$ at that height. It is found that if the chamber were brought to earth’s surface the clock in it would click correct time at $30^{\circ} C$ . The coefficient of linear expansion of the material of pendulum is (earth’s radius is $R$ ):

Discussion

43.	The resultant of two velocity vectors →A and →B is perpendicular to →A. Magnitude of resultant (→R) is equal to half of magnitude of →B. Find the angle between →A and →B
Answer» The resultant of two velocity vectors $\to A$ and $\to B$ is perpendicular to $\to A$ . Magnitude of resultant $(\to R)$ is equal to half of magnitude of $\to B$ . Find the angle between $\to A$ and $\to B$

Discussion

44.	Four particles of masses 1 g,2 g,3 g and 4 g are kept at points (0,0),(0,3 cm),(3 cm,3 cm),(3 cm,0 cm) respectively. Find the moment of inertia of the system of particles (in g-cm2) about x axis.
Answer» Four particles of masses $1 g, 2 g, 3 g$ and $4 g$ are kept at points $(0, 0), (0, 3 cm), (3 cm, 3 cm), (3 cm, 0 cm)$ respectively. Find the moment of inertia of the system of particles (in ${g-cm}^{2}$ ) about $x$ axis.

Discussion

45.	Three concentric metallic spherical shells of radii R, 2R, 3R, are given charges Q1, Q2 , Q3 respectively. It is found that the surface charge densities on the outer surfaces of the shells are equal. Then, the ratio of the charges given to the shells Q1:Q2:Q3, is
Answer» Three concentric metallic spherical shells of radii $R, 2 R, 3 R$ , are given charges $Q_{1}, Q_{2}, Q_{3}$ respectively. It is found that the surface charge densities on the outer surfaces of the shells are equal. Then, the ratio of the charges given to the shells $Q_{1} : Q_{2} : Q_{3}$ , is

Discussion

46.	10 g of ice at −20∘C is dropped into a calorimeter containing 10 g of water at 10∘C; the specific heat of water is twice that of ice. Ehen equilibrium is reached, the calorimeter will contain
Answer» 10 g of ice at $- 20^{\circ} C$ is dropped into a calorimeter containing 10 g of water at $10^{\circ} C$ ; the specific heat of water is twice that of ice. Ehen equilibrium is reached, the calorimeter will contain

Discussion

47.	p^ is an unit vector which represents the direction of an electric dipole from negative charge to the positive charge. Why only in the direction from negative charge to the positive charge? What is the actual direction of p^ or the electric dipole? please explain in deep...
Answer» p^ is an unit vector which represents the direction of an electric dipole from negative charge to the positive charge. Why only in the direction from negative charge to the positive charge? What is the actual direction of p^ or the electric dipole? please explain in deep...

Discussion

48.	A bird moves from point (1,-2) to (4,2).If the speed of the bird is 10m/sec . then the velocity vector of bird is?
Answer» A bird moves from point (1,-2) to (4,2).If the speed of the bird is 10m/sec . then the velocity vector of bird is?

Discussion

49.	A boy and a block, both of same mass m kg, are initially at the same horizontal level and attached to a frictionless pulley through a light inextensible string that moves over the frictionless pulley as shown in figure. The boy starts moving upward with an acceleration of 2.5 m/s2 relative to the rope. If the block has to travel a total distance of 10 m before reaching at the level of pulley, the time taken by the block in doing so is equal to
Answer» A boy and a block, both of same mass $m kg$ , are initially at the same horizontal level and attached to a frictionless pulley through a light inextensible string that moves over the frictionless pulley as shown in figure. The boy starts moving upward with an acceleration of $2.5 {m/s}^{2}$ relative to the rope. If the block has to travel a total distance of $10 m$ before reaching at the level of pulley, the time taken by the block in doing so is equal to

Discussion

50.	What happens to the lens of the eye when he watches the whole day to the near distances
Answer» What happens to the lens of the eye when he watches the whole day to the near distances

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

The electric field in a region is given by →E=(^3i−^4j) N/C. Find out the work done (in joule) in displacing a particle of charge 1C by 1 m along the line 4y = 3x + 9___

The time taken by a particle executing simple harmonic motion of time period T to move from the mean position to half the maximum displacement is

At what temperature will the rms speed of oxygen molecules becomes just sufficient to escape from the earth's atmosphere?(Given: Mass of oxygen molecule (m)=2.76×10−26 kg, Boltzmann constant i.e. kB=1.38×10−23JK−1)

The dimensional formula for relative density is

A block of mass m is placed on the floor of lift which is moving with velocity v=4t2, where t is time in second and velocity in m/s. Find the time at which normal force on the block is three times of its weight.

Two bodies M and N of equal masses are suspended from two separate spring of the spring s constant k1 and k2 respectively. If the two bodies oscillate vertically such that their maximum velocities are equal, the ratio of the amplitude of vibration of M to that on N is

ABCD is a square, O is the center of the square. −→F1, −→F2, −→F3 and −→F4 represent four forces acting along sides AB,BC,CA and AD respectively. If torque about O is zero then |−→F2| is

Two particles are kept on a smooth surface and they move towards each other. If the position and velocities of the particles at t=0 is as shown in the figure. Then position of the center of mass at t=2 sec is

A vessel whose bottom has a round hole with diameter 0.1 mm is filled with water. The maximum height up to which water can be filled without leakage is ............. cm (given surface tension =7.5×10−2Nm−1 and g=10ms−2

The value of which of the following quantities increases with increase in temperature for a conductor?

A proton, a deuteron and an α- particle having the same kinetic energy are moving in circular trajectories in a constant magnetic field. If rp, rd and rα denote respectively the radii of the trajectories of these particles, then

The electron beam in a colour TV is accelerated through 32 kV and then strikes the screen. What is the wavelength of the most energetic X-ray photon ?

Find the equivalent resistance of the networks shown in figure (32-E21) between the point a and b. figure (32-E21)

In LCR circuit, resonant frequency is 600 Hz and half power points are at 650 Hz and 550 Hz. The quality factor is

In the figure pulley p1 is fixed and p2 is movable. If W1=W2=100 N, what is the angle (in degrees) AP2P1 when the system is in equilibrium? The pulleys are massless and frictionless

The magnetic field B and the magnetic intensity H in a material are found to be 1.6 T and 1000 A m−1 respectively. Calculate the relative permeability μr and the susceptibility x of the material.

The area bounded by the line y=x+2 and x=−1 and x=1 is

A body builder exerts a force of 150 N against a bullworker and compresses it by 20 cm. Calculate the spring constant of the spring in the bullworker.

The mass M of the hanging block in figure which will prevent the small block from slipping over the triangular block, if all the surfaces are frictionless and the strings and the pulleys are light is

The wavelength of radiation emitted is λ0 when an electron jumps from the third to the second orbit of hydrogen atom. If the electron jumps from the fourth to the second orbit of the hydrogen atom, the wavelength of radiation emitted will be

Capacitors are charged and connected as shown in figure. If switch is closed at t=0, find work done by battery.

A coil carries a current and experiences a torque due to a magnetic filed. The value of the torque is 80% of the maximum possible torque. The angle between the magnetic field and the normal to the plane of the coil is

A beam of white light is incident normally on a plane surface absorbing 70% of the light and reflecting the rest. If the incident beam carries 10 W of power, find the force exerted by it on the surface.

A bat emits ultrasonic sound of frequency 1000 kHz in air. If the sound meets a water surface, what is the wavelength of (a) the reflected sound, (b) the transmitted sound? Speed of sound in air is 340ms−1 and in water 1486ms−1.

Plates of a parallel plate capacitor (C=6 nF) carries charge Q1=12 nC and Q2=6 nC, then energy stored in capacitor is

Half of the rectangular plate shown in figure is made of a material of density p1 and the other half of density p2. The length of the plate is L. Locate the centre of mass of the plate.

Consider the figure. The charge appearing on C2 is

During an experiment, a signal from a spaceship reached the ground station in five minutes. What was the distance of the spaceship from the ground station? The signal travels at the speed of light, that is, 3×108ms−1

The wave theory of light predicted that the stopping potential for a conductor in photoelectric effect, ______________ on increasing the frequency of light. Intensity is kept constant.

The value of coefficient of volume expansion of glycerin is 5×10−4 ∘C−1. The fractional change in the density of glycerin for a rise of 40 ∘C in its temperature is

Calculate the change in internal energy of a gas kept in a rigid container when 100 J of heat is supplied to it.

Find the angle between the vectors ^i−2^j+3^k and 3^i−2^j+^k

If velocity of a particle depends on time as v = t3+2√t. Then with what velocity is the particle moving at t = 4 sec and what is the displacement till then?

What is the translational kinetic energy of a Helium molecule (He) at 1500 K?

The resultant of two velocity vectors →A and →B is perpendicular to →A. Magnitude of resultant (→R) is equal to half of magnitude of →B. Find the angle between →A and →B

Four particles of masses 1 g,2 g,3 g and 4 g are kept at points (0,0),(0,3 cm),(3 cm,3 cm),(3 cm,0 cm) respectively. Find the moment of inertia of the system of particles (in g-cm2) about x axis.

Three concentric metallic spherical shells of radii R, 2R, 3R, are given charges Q1, Q2 , Q3 respectively. It is found that the surface charge densities on the outer surfaces of the shells are equal. Then, the ratio of the charges given to the shells Q1:Q2:Q3, is

10 g of ice at −20∘C is dropped into a calorimeter containing 10 g of water at 10∘C; the specific heat of water is twice that of ice. Ehen equilibrium is reached, the calorimeter will contain

p^ is an unit vector which represents the direction of an electric dipole from negative charge to the positive charge. Why only in the direction from negative charge to the positive charge? What is the actual direction of p^ or the electric dipole? please explain in deep...

A bird moves from point (1,-2) to (4,2).If the speed of the bird is 10m/sec . then the velocity vector of bird is?

What happens to the lens of the eye when he watches the whole day to the near distances