50278 + Interview Questions in Physics

1.	A refrigerator freezes water at 0∘C into 10 kg ice at 0∘C in a time interval of 30 min. Assuming the room temperature to be 22∘C, calculate the minimum amount of power needed to make 10 kg of ice. (Take latent heat for freezing as 80 kcal/kg)
Answer» A refrigerator freezes water at $0^{\circ} C$ into $10 kg$ ice at $0^{\circ} C$ in a time interval of $30 min$ . Assuming the room temperature to be $22^{\circ} C$ , calculate the minimum amount of power needed to make $10 kg$ of ice. (Take latent heat for freezing as $80 kcal/kg$ )

Discussion

2.	An object O is placed at a point distance x1 from the focus F1 of a converging lens of focal length f and its image I is formed at distance x2 from the focus F2 as shown in figure, then:
Answer» An object O is placed at a point distance $x_{1}$ from the focus $F_{1}$ of a converging lens of focal length f and its image I is formed at distance $x_{2}$ from the focus $F_{2}$ as shown in figure, then:

2.

An object O is placed at a point distance x1 from the focus F1 of a converging lens of focal length f and its image I is formed at distance x2 from the focus F2 as shown in figure, then:

Answer»

An object O is placed at a point distance $x_{1}$ from the focus $F_{1}$ of a converging lens of focal length f and its image I is formed at distance $x_{2}$ from the focus $F_{2}$ as shown in figure, then:

Discussion

3.	A capacitor of capacitance C1=1μF charged up to a voltage V=110 V is connected in parallel to the terminals of a circuit consisting of two uncharged capacitors connected in series and possessing the capacitance C2=2 μF and C3=3.0μF. Then what is the charge flowing through the wire
Answer» A capacitor of capacitance $C_{1} = 1 μ F$ charged up to a voltage $V = 110 V$ is connected in parallel to the terminals of a circuit consisting of two uncharged capacitors connected in series and possessing the capacitance $C_{2} = 2 μ F$ and $C_{3} = 3.0 μ F$ . Then what is the charge flowing through the wire

Discussion

4.	If a particle revolves in a circle of radius R, with time period T. The average speed and average velocity during two complete revolutions of the particle will respectively be
Answer» If a particle revolves in a circle of radius $R$ , with time period $T$ . The average speed and average velocity during two complete revolutions of the particle will respectively be

Discussion

5.	A body is projected with a velocity v at an angle of projection θ with the horizontal. The direction of velocity of the body makes angle 30∘ with the horizontal at t=2 s and then after further 1 s, it reaches the maximum height. Then (g=10 m/s2)
Answer» A body is projected with a velocity $v$ at an angle of projection $θ$ with the horizontal. The direction of velocity of the body makes angle $30^{\circ}$ with the horizontal at $t = 2 s$ and then after further $1 s$ , it reaches the maximum height. Then $(g = 10 {m/s}^{2})$

Discussion

6.	The magnitude of the rotational analog of linear momentum is .
Answer» The magnitude of the rotational analog of linear momentum is .

Discussion

7.	A long wire carrying a steady current is bent into a circular loop of one turn. The magnetic field at the centre of the loop is B. It is then bent into a circular coil of n turns. The magnetic field at the centre of this coil of n turns will be
Answer» A long wire carrying a steady current is bent into a circular loop of one turn. The magnetic field at the centre of the loop is $B$ . It is then bent into a circular coil of $n$ turns. The magnetic field at the centre of this coil of $n$ turns will be

Discussion

8.	A small planet is revolving around a very massive star in a circular orbit of radius R with a period of revolution T. If the gravitational force between the planet and the star is proportional to R−52, then T would be proportional to
Answer» A small planet is revolving around a very massive star in a circular orbit of radius $R$ with a period of revolution $T$ . If the gravitational force between the planet and the star is proportional to $R^{\frac{- 5}{2}}$ , then $T$ would be proportional to

Discussion

9.	Find the ratio of tensions T1 and T2 for the figure shown.
Answer» Find the ratio of tensions $T_{1}$ and $T_{2}$ for the figure shown.

Discussion

10.	Why the direction of current is opposite to the direction of flow of electrons?
Answer» Why the direction of current is opposite to the direction of flow of electrons?

Discussion

11.	Which one of the following graphs represent the velocity of a steel ball which falls from a height on to a marble floor?
Answer» Which one of the following graphs represent the velocity of a steel ball which falls from a height on to a marble floor?

Discussion

12.	A block is placed on the top of a smooth inclined plane of inclination θ kept on the floor of a lift. When the lift is descending with a retardation a, the block is released. The acceleration of the block relative to the incline is
Answer» A block is placed on the top of a smooth inclined plane of inclination $θ$ kept on the floor of a lift. When the lift is descending with a retardation $a$ , the block is released. The acceleration of the block relative to the incline is

Discussion

13.	Why we use rheostat in Meter bridge?
Answer» Why we use rheostat in Meter bridge?

Discussion

14.	Let 1.00 kg of liquid water at 100∘C be converted to steam at 100∘C by boiling at standard atmospheric pressure (which is 1.00 atm or 1.01 × 105 Pa) in the arrangement as shown. The volume of that water changes from an initial value of 1.00×10−3 m3 as a liquid to 1.671 m3 as steam. 1. How much work is done by the system during this process?
Answer» Let 1.00 kg of liquid water at $100^{\circ} C$ be converted to steam at $100^{\circ} C$ by boiling at standard atmospheric pressure (which is 1.00 atm or 1.01 $\times$ 105 Pa) in the arrangement as shown. The volume of that water changes from an initial value of $1.00 \times 10^{- 3}$ $m^{3}$ as a liquid to 1.671 $m^{3}$ as steam. 1. How much work is done by the system during this process?

14.

Let 1.00 kg of liquid water at 100∘C be converted to steam at 100∘C by boiling at standard atmospheric pressure (which is 1.00 atm or 1.01 × 105 Pa) in the arrangement as shown. The volume of that water changes from an initial value of 1.00×10−3 m3 as a liquid to 1.671 m3 as steam. 1. How much work is done by the system during this process?

Answer»

Let 1.00 kg of liquid water at $100^{\circ} C$ be converted to steam at $100^{\circ} C$ by boiling at standard atmospheric pressure (which is 1.00 atm or 1.01 $\times$ 105 Pa) in the arrangement as shown. The volume of that water changes from an initial value of $1.00 \times 10^{- 3}$ $m^{3}$ as a liquid to 1.671 $m^{3}$ as steam.

1. How much work is done by the system during this process?

Discussion

15.	A particle P is moving in a circle of radius R with a uniform speed v. C is the centre of the circle and AB is the diameter. The angular velocity of the particle when it is at point B about A and about C are in the ratio of
Answer» A particle P is moving in a circle of radius $R$ with a uniform speed $v$ . C is the centre of the circle and AB is the diameter. The angular velocity of the particle when it is at point B about A and about C are in the ratio of

Discussion

16.	A gas at certain volume and temperature has a pressure equal to 75 cm of mercury column. If the mass of the gas is doubled, at the same volume and temperature, its new pressure is
Answer» A gas at certain volume and temperature has a pressure equal to $75 cm$ of mercury column. If the mass of the gas is doubled, at the same volume and temperature, its new pressure is

Discussion

17.	The sum of all the angles in an octagon is
Answer» The sum of all the angles in an octagon is

Discussion

18.	In the given figure, masses of A and B are 5 kg and 10 kg respectively. Coefficient of friction between blocks is 0.2. If the lower block is pulled rightwards with a constant force, F=50 N, time elapsed before block A falls off block B is: (There is no friction between block B and surface) and neglect the size of A)
Answer» In the given figure, masses of $A$ and $B$ are $5 kg$ and $10 kg$ respectively. Coefficient of friction between blocks is 0.2. If the lower block is pulled rightwards with a constant force, $F = 50 N$ , time elapsed before block $A$ falls off block $B$ is: (There is no friction between block $B$ and surface) and neglect the size of $A$ )

Discussion

19.	A particle is projected upwards at an angle θ=45∘ with horizontal from the top of a tower 10 m high. Assume the origin is situated at the bottom of the tower and the speed at which the particle is projected is 40√2 m/s. Find the equation of trajectory of the particle.
Answer» A particle is projected upwards at an angle $θ = 45^{\circ}$ with horizontal from the top of a tower $10 m$ high. Assume the origin is situated at the bottom of the tower and the speed at which the particle is projected is $40 \sqrt{2} m/s$ . Find the equation of trajectory of the particle.

Discussion

20.	Why do resistors in series have different potential and a common current and resistors in parallel have different current and a common potential throughout?
Answer» Why do resistors in series have different potential and a common current and resistors in parallel have different current and a common potential throughout?

Discussion

21.	A body is projected vertically down from the top of a tower of hieght h ( = 40 m) with a velocity v1=5m/s. Another body is projected up from the bottom of the tower with vertically ipwards velocity v2=15m/s. When will the bodies meet ?
Answer» A body is projected vertically down from the top of a tower of hieght h ( = 40 m) with a velocity $v_{1} = 5 m / s$ . Another body is projected up from the bottom of the tower with vertically ipwards velocity $v_{2} = 15 m / s$ . When will the bodies meet ?

Discussion

22.	A signal of 5 kHz frequency is amplitude modulated on a carrier wave of frequency 2 MHz. the frequencies of the resultant signal is/are:
Answer» A signal of 5 kHz frequency is amplitude modulated on a carrier wave of frequency 2 MHz. the frequencies of the resultant signal is/are:

Discussion

23.	Two masses m1=5 kg and m2=10 kg, connected through an inextensible string over a frictionless pulley, are moving as shown in the figure. The coefficient of friction of horizontal surface is 0.15 (μk=μs=μ) . The minimum weight m that should be put on top of m2 to stop the motion is:
Answer» Two masses $m_{1} = 5 kg$ and $m_{2} = 10 kg,$ connected through an inextensible string over a frictionless pulley, are moving as shown in the figure. The coefficient of friction of horizontal surface is 0.15 ( $μ_{k} = μ_{s} = μ)$ . The minimum weight $m$ that should be put on top of $m_{2}$ to stop the motion is:

Discussion

24.	Three identical spherical shells, each of mass m and radius r are placed as shown in figure. Consider an axis XX′, which is touching to two shells and passing through diameter of third shell. Moment of inertia of the system consisting of these three spherical shells about XX′ axis is
Answer» Three identical spherical shells, each of mass $m$ and radius $r$ are placed as shown in figure. Consider an axis $X X^{'}$ , which is touching to two shells and passing through diameter of third shell. Moment of inertia of the system consisting of these three spherical shells about $X X^{'}$ axis is

Discussion

25.	A thin uniform rod of mass M and length L has its moment of inertia Irod about its perpendicular bisector. This rod is bend in the form of a circular shape of radius r. Now, circle has its moment of inertia Icircle about its centre and perpendicular to its plane. Find the ratio of Irod:Icircle.
Answer» A thin uniform rod of mass $M$ and length $L$ has its moment of inertia $I_{r o d}$ about its perpendicular bisector. This rod is bend in the form of a circular shape of radius $r$ . Now, circle has its moment of inertia $I_{circle}$ about its centre and perpendicular to its plane. Find the ratio of $I_{r o d} : I_{circle}$ .

Discussion

26.	The potential energy function of a particle is given by U=−(x2+y2+z2) J, where x,y and z are in meters. Find the force acting on the particle at point A(1 m,3 m,5 m).
Answer» The potential energy function of a particle is given by $U = - (x^{2} + y^{2} + z^{2}) J$ , where $x, y$ and $z$ are in meters. Find the force acting on the particle at point $A (1 m, 3 m, 5 m)$ .

Discussion

27.	What is the equivalent spring constant for the syatem shown below in the figure? (All the springs are ideal and identical having spring constant k N/m)
Answer» What is the equivalent spring constant for the syatem shown below in the figure? (All the springs are ideal and identical having spring constant $k N/m$ )

Discussion

28.	A cylindrical tank stands on a frictionless surface. The seal over a circular hole of radius 0.5 cm in the wall of the tank ruptures when the level of water above the hole is 1 metre. The force that a person must apply on the cylinder to keep it from being set in motion is
Answer» A cylindrical tank stands on a frictionless surface. The seal over a circular hole of radius 0.5 cm in the wall of the tank ruptures when the level of water above the hole is 1 metre. The force that a person must apply on the cylinder to keep it from being set in motion is

Discussion

29.	How internal forces can create a torque ,angular acceleration and rotate a body?
Answer» How internal forces can create a torque ,angular acceleration and rotate a body?

Discussion

30.	A ball of mass m is initially at rest. A variable force starts acting on it in a fixed direction, whose magnitude changes with time. The force - time graph is shown in the figure. Find the speed of the ball at the end of time t=T seconds.
Answer» A ball of mass $m$ is initially at rest. A variable force starts acting on it in a fixed direction, whose magnitude changes with time. The force - time graph is shown in the figure. Find the speed of the ball at the end of time $t = T$ seconds.

Discussion

31.	A ball of radius R=50 cm is located in a non-magnetic medium with permitivity k = 4.0. In that medium a plane electromagnetic wave propagates, the strength amplitude of whose electric component is equal to Em=200V/m. The amount of energy that reaches the ball during a time interval of t=1.0min is (in kJ) ?
Answer» A ball of radius R=50 cm is located in a non-magnetic medium with permitivity k = 4.0. In that medium a plane electromagnetic wave propagates, the strength amplitude of whose electric component is equal to $E_{m} = 200 V / m$ . The amount of energy that reaches the ball during a time interval of $t = 1.0 min$ is (in kJ) ?

Discussion

32.	If sin 15∘θ.sec15∘θ=1 then θ= ___
Answer» If $s i n 15^{\circ} θ . s e c 15^{\circ} θ = 1 t h e n θ =$ ___

Discussion

33.	The separation L between the objective (f=0.5cm) and the eyepiece (f=5 cm) of a compound microscope is 7 cm. If a small object be placed so that the eye is least strained to see the image, find the angular magnification produced by the microscope.
Answer» The separation $L$ between the objective $(f = 0.5 c m)$ and the eyepiece $(f = 5 c m)$ of a compound microscope is $7 c m$ . If a small object be placed so that the eye is least strained to see the image, find the angular magnification produced by the microscope.

Discussion

34.	Which one of the following represents forward bias diode?
Answer» Which one of the following represents forward bias diode?

Discussion

35.	Two bodies of masses 10 kg and 20 kg respectively kept on a smooth, horizontal surface are tied to the ends of a light string. A horizontal force F = 600 N is applied to (i) A, (ii) B along the direction of string. What is the tension in the string in each case?
Answer» Two bodies of masses 10 kg and 20 kg respectively kept on a smooth, horizontal surface are tied to the ends of a light string. A horizontal force F = 600 N is applied to (i) A, (ii) B along the direction of string. What is the tension in the string in each case?

Discussion

36.	A monkey is sitting on a tree limb. The limb exerts a normal force of 48 N and a frictional force of 20 N. Find the magnitude of the total force exerted by the limb on the monkey.
Answer» A monkey is sitting on a tree limb. The limb exerts a normal force of 48 N and a frictional force of 20 N. Find the magnitude of the total force exerted by the limb on the monkey.

Discussion

37.	If a particle of mass m is moving with constant velocity v parallel to x-axis in x-y plane as shown in fig. Its angular momentum with respect to origin at any time t will be
Answer» If a particle of mass m is moving with constant velocity v parallel to x-axis in x-y plane as shown in fig. Its angular momentum with respect to origin at any time t will be

Discussion

38.	A piece of wood is taken deep inside a long column of water and released it will move up
Answer» A piece of wood is taken deep inside a long column of water and released it will move up

Discussion

39.	Threshold wavelength for photoelectric effect on sodium is 5000 ∘A. Its work function is
Answer» Threshold wavelength for photoelectric effect on sodium is 5000 $\circ A$ . Its work function is

Discussion

40.	Find the derivative of y=(x2+1)(x3+3).
Answer» Find the derivative of $y = (x^{2} + 1) (x^{3} + 3)$ .

Discussion

41.	Figure shows a three arm tube in which a liquid is filled upto levels of height l. It is now rotated at an angular frequency ω about an axis passing through arm B. The angular frequency ω at which level of liquid in arm B becomes zero is
Answer» Figure shows a three arm tube in which a liquid is filled upto levels of height $l$ . It is now rotated at an angular frequency $ω$ about an axis passing through arm $B$ . The angular frequency $ω$ at which level of liquid in arm $B$ becomes zero is

Discussion

42.	A disk of radiusa4 having a uniformly distributed charge 6 C is placed in the x-y plane with its centre at (−a2,0,0).Arod of length a carrying a uniformly distributed charge 8 C is placed on the x-axis from x=a4to x=5a4.Two point charges –7 C and 3 C are placed at (a4,−a4,0)and(−3a4,3a4,0),respectively. Consider a cubical surface formed by six surfaces x=±a2,y=±a2,z=±a2.The electric flux through this cubical surface is:
Answer» A disk of radius $\frac{a}{4}$ having a uniformly distributed charge 6 C is placed in the x-y plane with its centre at $(\frac{- a}{2}, 0, 0) . A$ rod of length a carrying a uniformly distributed charge 8 C is placed on the x-axis from $x = \frac{a}{4} t o x = \frac{5 a}{4} .$ Two point charges –7 C and 3 C are placed at $(\frac{a}{4}, \frac{- a}{4}, 0) a n d (\frac{- 3 a}{4}, \frac{3 a}{4}, 0),$ respectively. Consider a cubical surface formed by six surfaces $x = \pm \frac{a}{2}, y = \pm \frac{a}{2}, z = \pm \frac{a}{2}$ .The electric flux through this cubical surface is:

Discussion

43.	A particle is travelling with uniform acceleration of magnitude a. During successive time intervals of Δt1,Δt2 and Δt3, its average velocities are v1,v2 and v3 respectively. Then,
Answer» A particle is travelling with uniform acceleration of magnitude a. During successive time intervals of $Δ t_{1}, Δ t_{2}$ and $Δ t_{3}$ , its average velocities are $v_{1}, v_{2}$ and $v_{3}$ respectively. Then,

Discussion

44.	A electron experiences a force (4.0^i+3.0^j)×10−13N in a uniform magnetic field when its velocity is 2.5^k×107 ms−1. When the velocity becomes (1.5^i−2.0^j)×107 ms−1, the magnetic force of the electron is zero. The magnetic field vector →B is:
Answer» A electron experiences a force $(4.0^i + 3.0^j) \times 10^{- 13} N$ in a uniform magnetic field when its velocity is $2.5^k \times 10^{7} {m s}^{- 1}$ . When the velocity becomes $(1.5^i - 2.0^j) \times 10^{7} {ms}^{- 1}$ , the magnetic force of the electron is zero. The magnetic field vector $\to B$ is:

Discussion

45.	The water equivalent of a copper colorimeter is 4.5g. If specific heat of copper is 0.09 cal /g/∘C, then 1) Mass of the calorimeter is 0.5kg 2) Thermal capacity of the calorimeter is 4.5 cal/ C 3)The heat required to raise the temperature of the calorimeter by 8∘C will be 36 cal. 4) Heat required to melt 15 gm of ice placed in the calorimeter will be 1200 cal Choose the correct option from below
Answer» The water equivalent of a copper colorimeter is 4.5g. If specific heat of copper is 0.09 cal /g/ $^{\circ}$ C, then 1) Mass of the calorimeter is 0.5kg 2) Thermal capacity of the calorimeter is 4.5 cal/ C 3)The heat required to raise the temperature of the calorimeter by 8 $^{\circ}$ C will be 36 cal. 4) Heat required to melt 15 gm of ice placed in the calorimeter will be 1200 cal Choose the correct option from below

Discussion

46.	A motor pump-set of efficiency 80% lifts 6000 litres of water per minute from a well 20 meters deep. If g=10 ms−2, then its input power is
Answer» A motor pump-set of efficiency $80 %$ lifts $6000$ litres of water per minute from a well $20$ meters deep. If $g = 10 m s^{- 2}$ , then its input power is

Discussion

47.	As shown in the figure, Two Loudspeakers are located at point A and B. Both are vibrating in phase at a frequency f and P1 and P2 are their respective power outputs. Point C lies on a line joining the two loudspeakers at a distance of d1 from A and d2 from B. Take velocity of sound = 300ms–1, frequency f=100Hz.d1=1m and d2=1.5m.P1=8π watts and P2=18π watts. Also, assume that loudspeakers behave like point isotropic sources. (emit sound uniformly in all directions).With both speakers switched on, the intensity (in W/m2) at point___
Answer» As shown in the figure, Two Loudspeakers are located at point A and B. Both are vibrating in phase at a frequency f and $P_{1}$ and $P_{2}$ are their respective power outputs. Point C lies on a line joining the two loudspeakers at a distance of $d_{1}$ from A and $d_{2}$ from B. Take velocity of sound = 300ms–1, frequency $f = 100 H z . d_{1} = 1 m$ and $d_{2} = 1.5 m . P_{1} = 8 π$ watts and $P_{2} = 18 π$ watts. Also, assume that loudspeakers behave like point isotropic sources. (emit sound uniformly in all directions).With both speakers switched on, the intensity (in W/m2) at point___

47.

As shown in the figure, Two Loudspeakers are located at point A and B. Both are vibrating in phase at a frequency f and P1 and P2 are their respective power outputs. Point C lies on a line joining the two loudspeakers at a distance of d1 from A and d2 from B. Take velocity of sound = 300ms–1, frequency f=100Hz.d1=1m and d2=1.5m.P1=8π watts and P2=18π watts. Also, assume that loudspeakers behave like point isotropic sources. (emit sound uniformly in all directions).With both speakers switched on, the intensity (in W/m2) at point___

Answer»

As shown in the figure, Two Loudspeakers are located at point A and B. Both are vibrating in phase at a frequency f and $P_{1}$ and $P_{2}$ are their respective power outputs. Point C lies on a line joining the two loudspeakers at a distance of $d_{1}$ from A and $d_{2}$ from B. Take velocity of sound = 300ms–1, frequency $f = 100 H z . d_{1} = 1 m$ and $d_{2} = 1.5 m . P_{1} = 8 π$ watts and $P_{2} = 18 π$ watts. Also, assume that loudspeakers behave like point isotropic sources. (emit sound uniformly in all directions).With both speakers switched on, the intensity (in W/m2) at point___

Discussion

48.	A box of mass 70 kg is being lifted by a helicopter with the help of a rope, which can bear a maximum tension of 100 kg wt. The maximum acceleration with which helicopter should rise so that the rope does not break will be (Given g=9.8 m/s2)
Answer» A box of mass $70 k g$ is being lifted by a helicopter with the help of a rope, which can bear a maximum tension of $100 k g$ wt. The maximum acceleration with which helicopter should rise so that the rope does not break will be (Given $g = 9.8 m / s^{2}$ )

Discussion

49.	The mass and density of a solid sphere are measured to be (12.4±0.1) kg and (4.60±0.2) kg/m3. The volume of the sphere expressed with error limits is:
Answer» The mass and density of a solid sphere are measured to be $(12.4 \pm 0.1) kg$ and $(4.60 \pm 0.2) {kg/m}^{3}$ . The volume of the sphere expressed with error limits is:

Discussion

50.	A cube of side 20cm is floating on liquid with 5cm of the cube outside the liquid. If the density of liquid is 0.8 gm/c.c then the mass of the cube is
Answer» A cube of side 20cm is floating on liquid with 5cm of the cube outside the liquid. If the density of liquid is 0.8 gm/c.c then the mass of the cube is

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A refrigerator freezes water at 0∘C into 10 kg ice at 0∘C in a time interval of 30 min. Assuming the room temperature to be 22∘C, calculate the minimum amount of power needed to make 10 kg of ice. (Take latent heat for freezing as 80 kcal/kg)

An object O is placed at a point distance x1 from the focus F1 of a converging lens of focal length f and its image I is formed at distance x2 from the focus F2 as shown in figure, then:

A capacitor of capacitance C1=1μF charged up to a voltage V=110 V is connected in parallel to the terminals of a circuit consisting of two uncharged capacitors connected in series and possessing the capacitance C2=2 μF and C3=3.0μF. Then what is the charge flowing through the wire

If a particle revolves in a circle of radius R, with time period T. The average speed and average velocity during two complete revolutions of the particle will respectively be

A body is projected with a velocity v at an angle of projection θ with the horizontal. The direction of velocity of the body makes angle 30∘ with the horizontal at t=2 s and then after further 1 s, it reaches the maximum height. Then (g=10 m/s2)

The magnitude of the rotational analog of linear momentum is .

A long wire carrying a steady current is bent into a circular loop of one turn. The magnetic field at the centre of the loop is B. It is then bent into a circular coil of n turns. The magnetic field at the centre of this coil of n turns will be

A small planet is revolving around a very massive star in a circular orbit of radius R with a period of revolution T. If the gravitational force between the planet and the star is proportional to R−52, then T would be proportional to

Find the ratio of tensions T1 and T2 for the figure shown.

Why the direction of current is opposite to the direction of flow of electrons?

Which one of the following graphs represent the velocity of a steel ball which falls from a height on to a marble floor?

A block is placed on the top of a smooth inclined plane of inclination θ kept on the floor of a lift. When the lift is descending with a retardation a, the block is released. The acceleration of the block relative to the incline is

Why we use rheostat in Meter bridge?

A particle P is moving in a circle of radius R with a uniform speed v. C is the centre of the circle and AB is the diameter. The angular velocity of the particle when it is at point B about A and about C are in the ratio of

A gas at certain volume and temperature has a pressure equal to 75 cm of mercury column. If the mass of the gas is doubled, at the same volume and temperature, its new pressure is

The sum of all the angles in an octagon is

A particle is projected upwards at an angle θ=45∘ with horizontal from the top of a tower 10 m high. Assume the origin is situated at the bottom of the tower and the speed at which the particle is projected is 40√2 m/s. Find the equation of trajectory of the particle.

Why do resistors in series have different potential and a common current and resistors in parallel have different current and a common potential throughout?

A body is projected vertically down from the top of a tower of hieght h ( = 40 m) with a velocity v1=5m/s. Another body is projected up from the bottom of the tower with vertically ipwards velocity v2=15m/s. When will the bodies meet ?

A signal of 5 kHz frequency is amplitude modulated on a carrier wave of frequency 2 MHz. the frequencies of the resultant signal is/are:

Two masses m1=5 kg and m2=10 kg, connected through an inextensible string over a frictionless pulley, are moving as shown in the figure. The coefficient of friction of horizontal surface is 0.15 (μk=μs=μ) . The minimum weight m that should be put on top of m2 to stop the motion is:

Three identical spherical shells, each of mass m and radius r are placed as shown in figure. Consider an axis XX′, which is touching to two shells and passing through diameter of third shell. Moment of inertia of the system consisting of these three spherical shells about XX′ axis is

A thin uniform rod of mass M and length L has its moment of inertia Irod about its perpendicular bisector. This rod is bend in the form of a circular shape of radius r. Now, circle has its moment of inertia Icircle about its centre and perpendicular to its plane. Find the ratio of Irod:Icircle.

The potential energy function of a particle is given by U=−(x2+y2+z2) J, where x,y and z are in meters. Find the force acting on the particle at point A(1 m,3 m,5 m).

What is the equivalent spring constant for the syatem shown below in the figure? (All the springs are ideal and identical having spring constant k N/m)

A cylindrical tank stands on a frictionless surface. The seal over a circular hole of radius 0.5 cm in the wall of the tank ruptures when the level of water above the hole is 1 metre. The force that a person must apply on the cylinder to keep it from being set in motion is

How internal forces can create a torque ,angular acceleration and rotate a body?

A ball of mass m is initially at rest. A variable force starts acting on it in a fixed direction, whose magnitude changes with time. The force - time graph is shown in the figure. Find the speed of the ball at the end of time t=T seconds.

If sin 15∘θ.sec15∘θ=1 then θ= ___

The separation L between the objective (f=0.5cm) and the eyepiece (f=5 cm) of a compound microscope is 7 cm. If a small object be placed so that the eye is least strained to see the image, find the angular magnification produced by the microscope.

Which one of the following represents forward bias diode?

Two bodies of masses 10 kg and 20 kg respectively kept on a smooth, horizontal surface are tied to the ends of a light string. A horizontal force F = 600 N is applied to (i) A, (ii) B along the direction of string. What is the tension in the string in each case?

A monkey is sitting on a tree limb. The limb exerts a normal force of 48 N and a frictional force of 20 N. Find the magnitude of the total force exerted by the limb on the monkey.

If a particle of mass m is moving with constant velocity v parallel to x-axis in x-y plane as shown in fig. Its angular momentum with respect to origin at any time t will be

A piece of wood is taken deep inside a long column of water and released it will move up

Threshold wavelength for photoelectric effect on sodium is 5000 ∘A. Its work function is

Find the derivative of y=(x2+1)(x3+3).

Figure shows a three arm tube in which a liquid is filled upto levels of height l. It is now rotated at an angular frequency ω about an axis passing through arm B. The angular frequency ω at which level of liquid in arm B becomes zero is

A particle is travelling with uniform acceleration of magnitude a. During successive time intervals of Δt1,Δt2 and Δt3, its average velocities are v1,v2 and v3 respectively. Then,

A electron experiences a force (4.0^i+3.0^j)×10−13N in a uniform magnetic field when its velocity is 2.5^k×107 ms−1. When the velocity becomes (1.5^i−2.0^j)×107 ms−1, the magnetic force of the electron is zero. The magnetic field vector →B is:

A motor pump-set of efficiency 80% lifts 6000 litres of water per minute from a well 20 meters deep. If g=10 ms−2, then its input power is

A box of mass 70 kg is being lifted by a helicopter with the help of a rope, which can bear a maximum tension of 100 kg wt. The maximum acceleration with which helicopter should rise so that the rope does not break will be (Given g=9.8 m/s2)

The mass and density of a solid sphere are measured to be (12.4±0.1) kg and (4.60±0.2) kg/m3. The volume of the sphere expressed with error limits is:

A cube of side 20cm is floating on liquid with 5cm of the cube outside the liquid. If the density of liquid is 0.8 gm/c.c then the mass of the cube is