50278 + Interview Questions in Physics

1.	In Young’s double slit experiment, the aperture screen distance is 2 m. The fringe width is 1 mm. Light of 600 nm is used. If a thin plate of glass (μ=1.5) of thickness 0.06 mm is placed over one of the slit, then there will be a lateral displacement of the fringe by:
Answer» In Young’s double slit experiment, the aperture screen distance is $2 m$ . The fringe width is $1 mm$ . Light of $600 nm$ is used. If a thin plate of glass $(μ = 1.5)$ of thickness $0.06 mm$ is placed over one of the slit, then there will be a lateral displacement of the fringe by:

Discussion

2.	A stone is placed at the bottom of lake of depth 10 m. Refractive index of water of lake is μ=(1+y10) where 'y' is depth of water from surface. A person looks at stone normally, then depth at which stone appears to him in meters is (ln 2 = 0.693). Write upto two digits after the decimal point.
Answer» A stone is placed at the bottom of lake of depth 10 m. Refractive index of water of lake is $μ = (1 + \frac{y}{10})$ where 'y' is depth of water from surface. A person looks at stone normally, then depth at which stone appears to him in meters is (ln 2 = 0.693). Write upto two digits after the decimal point.

Discussion

3.	According to Newton’s first law of motion, force is necessary to
Answer» According to Newton’s first law of motion, force is necessary to

Discussion

4.	The electric and magnetic fields produced by the radiation coming from a 100 W bulb at a distance of 3m is respectively [Assume that the efficiency of the bulb is 2.5% and it is a point source]
Answer» The electric and magnetic fields produced by the radiation coming from a 100 W bulb at a distance of 3m is respectively [Assume that the efficiency of the bulb is $2.5 %$ and it is a point source]

Discussion

5.	A 100 W bulb B1, and two 60 W bulbs B2 and B3, are connected to a 250 V source as shown in the figure. Now W1,W2 and W3 are the output powers of the bulbs B1,B2 and B3 respectively. Then
Answer» A 100 W bulb $B_{1}$ , and two 60 W bulbs $B_{2}$ and $B_{3}$ , are connected to a 250 V source as shown in the figure. Now $W_{1}, W_{2}$ and $W_{3}$ are the output powers of the bulbs $B_{1}, B_{2}$ and $B_{3}$ respectively. Then

5.

A 100 W bulb B1, and two 60 W bulbs B2 and B3, are connected to a 250 V source as shown in the figure. Now W1,W2 and W3 are the output powers of the bulbs B1,B2 and B3 respectively. Then

Answer»

A 100 W bulb $B_{1}$ , and two 60 W bulbs $B_{2}$ and $B_{3}$ , are connected to a 250 V source as shown in the figure. Now $W_{1}, W_{2}$ and $W_{3}$ are the output powers of the bulbs $B_{1}, B_{2}$ and $B_{3}$ respectively. Then

Discussion

6.	Four weightless rods of length l each are connected by hinged joints and form a rhombus as shown in figure. Hinge A is fixed and load of mass m is suspended to hinge C. Hinges B and D are connected by weightless spring of length 1.5l in undeformed state. At equilibrium θ=30o, then the time period of SHM of block if displaced slightly is T=2π√nmk, here n is [Write upto two digits after the decimal.]
Answer» Four weightless rods of length $l$ each are connected by hinged joints and form a rhombus as shown in figure. Hinge A is fixed and load of mass m is suspended to hinge C. Hinges B and D are connected by weightless spring of length $1.5 l$ in undeformed state. At equilibrium $θ = 30^{o}$ , then the time period of SHM of block if displaced slightly is $T = 2 π \sqrt{\frac{n m}{k}}$ , here $n$ is [Write upto two digits after the decimal.]

Discussion

7.	Assuming steady state one-dimensional heat conduction in a composite slab, if Tinter=T1+T22, then which of the following statements is true about the respective thermal conductivities?
Answer» Assuming steady state one-dimensional heat conduction in a composite slab, if $T_{i n t e r} = \frac{T_{1} + T_{2}}{2},$ then which of the following statements is true about the respective thermal conductivities?

Discussion

8.	A stretched sonometer wire resonates at a frequency of 350 Hz and at the next higher frequency of 420 Hz. The fundamental frequency of this wire is :
Answer» A stretched sonometer wire resonates at a frequency of $350 Hz$ and at the next higher frequency of $420 Hz$ . The fundamental frequency of this wire is :

Discussion

9.	When photons of energy 5 eV strike the surface of a metal A, the ejected photoelectrons have maximum kinetic energy KA eVand de Broglie wavelength λA The maximum kinetic energy of photoelectrons liberated from another metal B by photons of energy 5.30 eV is KB=(KA−1.5).eV If the de Broglie wavelength of these photoelectrons is λB=2λA then find KA in electron volt.
Answer» When photons of energy 5 eV strike the surface of a metal A, the ejected photoelectrons have maximum kinetic energy $K_{A} e V$ and de Broglie wavelength $λ_{A}$ The maximum kinetic energy of photoelectrons liberated from another metal B by photons of energy 5.30 eV is $K_{B} = (K_{A} - 1.5) . e V$ If the de Broglie wavelength of these photoelectrons is $λ_{B} = 2 λ_{A}$ then find $K_{A}$ in electron volt.

Discussion

10.	The pressure and density of a diatomic gas (γ=75) change adiabatically form (p1,d1) to (p2,d2). If d2d1=32, then p2p1 is
Answer» The pressure and density of a diatomic gas $(γ = \frac{7}{5})$ change adiabatically form $(p_{1}, d_{1})$ to $(p_{2}, d_{2})$ . If $\frac{d_{2}}{d_{1}} = 32, t h e n \frac{p_{2}}{p_{1}}$ is

Discussion

11.	A ball is projected from point A with velocity 10 m/s perpendicular to the inclined plane as shown in figure. Range of the ball on the inclined plane is equal to N3 m. Then, N is equal to
Answer» A ball is projected from point $A$ with velocity $10 m/s$ perpendicular to the inclined plane as shown in figure. Range of the ball on the inclined plane is equal to $\frac{N}{3} m$ . Then, $N$ is equal to

Discussion

12.	Find the acceleration of the particle at x=3 m.
Answer» Find the acceleration of the particle at $x = 3 m$ .

Discussion

13.	A body is projected vertically upwards from the bottom of a crater of moon of depth R100 where R is the radius of moon with a velocity equal to the escape velocity on the surface of moon. Maximum height attained by the body from the surface of the moon is KR.The value of K is
Answer» A body is projected vertically upwards from the bottom of a crater of moon of depth $\frac{R}{100}$ where R is the radius of moon with a velocity equal to the escape velocity on the surface of moon. Maximum height attained by the body from the surface of the moon is KR.The value of K is

Discussion

14.	The binding energy per nucleon of 21H and 42He are 1.1 MeV and 7.0 MeV respectively. Energy released in the process 21H+21H→42He is
Answer» The binding energy per nucleon of $_{1}^{2} H$ and $_{2}^{4} H e$ are $1.1 M e V$ and $7.0 M e V$ respectively. Energy released in the process $_{1}^{2} H +_{1}^{2} H \to_{2}^{4} H e$ is

Discussion

15.	Derive relationship between Moment of inertia , angular velocity and torque
Answer» Derive relationship between Moment of inertia , angular velocity and torque

Discussion

16.	In J.J. Thomson’s method, electric field E, magnetic field B and velocity v of the electron were in mutually perpendicular direction. This velocity selector allows particles of velocity v to pass undeflected when (correct answer + 1, wrong answer - 0.25)
Answer» In J.J. Thomson’s method, electric field $E$ , magnetic field $B$ and velocity $v$ of the electron were in mutually perpendicular direction. This velocity selector allows particles of velocity $v$ to pass undeflected when (correct answer + 1, wrong answer - 0.25)

Discussion

17.	120 g of ice at 0∘C is mixed with 100 g of water at 80∘C . Latent heat of fusion is 80 cal/g and specific heat of water is 1 cal/g∘C. The final temperature of the mixture is (correct answer + 1, wrong answer - 0.25)
Answer» $120 g$ of ice at $0^{\circ} C$ is mixed with $100 g$ of water at $80^{\circ} C$ . Latent heat of fusion is $80 cal/g$ and specific heat of water is $1 {cal/g}^{\circ} C$ . The final temperature of the mixture is (correct answer + 1, wrong answer - 0.25)

Discussion

18.	The direction of the force on the conductor when the direction of the magnetic field and current are given was found to be the opposite to the actual direction of the force on the conductor. Consider the given reasons why the wrong direction was obtained and choose the correct answers: Statement 1: The middle finger is taken as the direction of force and the thumb is taken as the direction of the current. Statement 2: The right hand is used instead of the left hand.
Answer» The direction of the force on the conductor when the direction of the magnetic field and current are given was found to be the opposite to the actual direction of the force on the conductor. Consider the given reasons why the wrong direction was obtained and choose the correct answers: Statement 1: The middle finger is taken as the direction of force and the thumb is taken as the direction of the current. Statement 2: The right hand is used instead of the left hand.

Discussion

19.	Consider a wheel purely rolling on a rough horizontal surface with constant velocity v. Radius of the wheel is R and C is the center of wheel. M is top-most point, P is bottom-most point and N is in level with C at any time. Match the columns for this instant of time.
Answer» Consider a wheel purely rolling on a rough horizontal surface with constant velocity v. Radius of the wheel is R and C is the center of wheel. M is top-most point, P is bottom-most point and N is in level with C at any time. Match the columns for this instant of time.

19.

Consider a wheel purely rolling on a rough horizontal surface with constant velocity v. Radius of the wheel is R and C is the center of wheel. M is top-most point, P is bottom-most point and N is in level with C at any time. Match the columns for this instant of time.

Answer»

Consider a wheel purely rolling on a rough horizontal surface with constant velocity v. Radius of the wheel is R and C is the center of wheel. M is top-most point, P is bottom-most point and N is in level with C at any time. Match the columns for this instant of time.

Discussion

20.	Is there a condition that if velocity is positive,acceleration should be negative?
Answer» Is there a condition that if velocity is positive,acceleration should be negative?

Discussion

21.	A particle performing SHM has a velocity v0 at mean position. Find the velocity of the particle, when it reaches a point which is at a distance A2 from the mean position. [A= amplitude of SHM]
Answer» A particle performing SHM has a velocity $v_{0}$ at mean position. Find the velocity of the particle, when it reaches a point which is at a distance $\frac{A}{2}$ from the mean position. [ $A =$ amplitude of SHM]

Discussion

22.	Two Radioactive substances X and Y emit α and β particles respectively. Their disintegration constants are in the ratio 2 : 3. To have equal rate of disintegration of getting emission of α and β particles., the ratio of number of atoms of X to that of Y at any time instant is
Answer» Two Radioactive substances X and Y emit $α$ and $β$ particles respectively. Their disintegration constants are in the ratio 2 : 3. To have equal rate of disintegration of getting emission of $α$ and $β$ particles., the ratio of number of atoms of X to that of Y at any time instant is

Discussion

23.	Figure represents a glass plate placed vertically on a horizontal table with a beam of unpolarised light falling on its surface at the polarizing angle of 57∘ with the normal. The electric vector in the reflected light on screen S will vibrate with respect to the plane of incidence in a
Answer» Figure represents a glass plate placed vertically on a horizontal table with a beam of unpolarised light falling on its surface at the polarizing angle of $57^{\circ}$ with the normal. The electric vector in the reflected light on screen S will vibrate with respect to the plane of incidence in a

23.

Figure represents a glass plate placed vertically on a horizontal table with a beam of unpolarised light falling on its surface at the polarizing angle of 57∘ with the normal. The electric vector in the reflected light on screen S will vibrate with respect to the plane of incidence in a

Answer»

Figure represents a glass plate placed vertically on a horizontal table with a beam of unpolarised light falling on its surface at the polarizing angle of $57^{\circ}$ with the normal. The electric vector in the reflected light on screen S will vibrate with respect to the plane of incidence in a

Discussion

24.	Two disc of same radius (r) and mass (m) are placed such that their centre is at a common point and their planes are perpendicular to each other. The moment of inertia of the system about an axis passing through the centre and perpendicular to plane of one of the discs is:
Answer» Two disc of same radius (r) and mass (m) are placed such that their centre is at a common point and their planes are perpendicular to each other. The moment of inertia of the system about an axis passing through the centre and perpendicular to plane of one of the discs is:

Discussion

25.	Why rolling friction is less than sliding friction?
Answer» Why rolling friction is less than sliding friction?

Discussion

26.	A certain prism is found to produce a minimum deviation of 38∘. It produces a deviation of 44∘ when the angle of incidence is either 42∘ or 62∘ . What is the angle of incidence when it is undergoing minimum deviation?
Answer» A certain prism is found to produce a minimum deviation of $38^{\circ}$ . It produces a deviation of $44^{\circ}$ when the angle of incidence is either $42^{\circ}$ or $62^{\circ}$ . What is the angle of incidence when it is undergoing minimum deviation?

Discussion

27.	A body of mass m accelerates uniformly from rest to v1 in time t1. The instantaneous power delivered to the body as a function of time t is
Answer» A body of mass m accelerates uniformly from rest to $v_{1}$ in time $t_{1}$ . The instantaneous power delivered to the body as a function of time t is

Discussion

28.	Transverse waves are generated in two uniform steel wires A and B when a source of frequency 500 Hz is attached to their free-ends. The diameter of A is half that of B and the tension in A is half that in B. The ratio of the velocity of the waves in wires A and B is
Answer» Transverse waves are generated in two uniform steel wires A and B when a source of frequency 500 Hz is attached to their free-ends. The diameter of A is half that of B and the tension in A is half that in B. The ratio of the velocity of the waves in wires A and B is

Discussion

29.	A capillary tube A is dipped in water. Another identical tube B is dipped in a soap - water solution. Which of the following shows the relative nature of the liquid columns in the two tubes?
Answer» A capillary tube $A$ is dipped in water. Another identical tube $B$ is dipped in a soap - water solution. Which of the following shows the relative nature of the liquid columns in the two tubes?

Discussion

30.	Q27) Which of the following book was not authored by Late Avul Pakir Jainulabdeen Abdul Kalam the Former Indian President who passed away recently?
Answer» Q27) Which of the following book was not authored by Late Avul Pakir Jainulabdeen Abdul Kalam the Former Indian President who passed away recently?

Discussion

31.	How can we say ions like Helium , beryllium,etc are hydrogen like sprcies.? Pls explain.
Answer» How can we say ions like Helium , beryllium,etc are hydrogen like sprcies.? Pls explain.

31.

How can we say ions like Helium , beryllium,etc are hydrogen like sprcies.? Pls explain.

Answer»

How can we say ions like Helium , beryllium,etc are hydrogen like sprcies.?

Pls explain.

Discussion

32.	Light of wavelength 5.0×10−7 m falls on a pair of narrow slits separated by a distance d. The interference pattern on a screen placed 2.0 m away shows that there is first dark fringe at the positions exactly opposite to each slit. The separation between the slits is:
Answer» Light of wavelength $5.0 \times 10^{- 7} m$ falls on a pair of narrow slits separated by a distance $d$ . The interference pattern on a screen placed $2.0 m$ away shows that there is first dark fringe at the positions exactly opposite to each slit. The separation between the slits is:

Discussion

33.	A parallel beam of light of wavelength λ is incident normally on a narrow slit. A diffraction pattern is formed on a screen placed perpendicular to the direction of the incident beam. At the second minimum of the diffraction pattern, the phase difference between the rays coming from the two edges of slit is
Answer» A parallel beam of light of wavelength $λ$ is incident normally on a narrow slit. A diffraction pattern is formed on a screen placed perpendicular to the direction of the incident beam. At the second minimum of the diffraction pattern, the phase difference between the rays coming from the two edges of slit is

Discussion

34.	A man is 180 cm tall and his eyes are 10 cm below the top of his head. In order to see this entire height right from toe to head, he uses a plane mirror kept at a distance of 1 m from him. The minimum length of the plane mirror is
Answer» A man is $180 cm$ tall and his eyes are $10 cm$ below the top of his head. In order to see this entire height right from toe to head, he uses a plane mirror kept at a distance of $1 m$ from him. The minimum length of the plane mirror is

Discussion

35.	Each of these questions are based on the information given below: A ,B, C, D and E are five men sitting in a line facing to south - while M, N, O, P and Q are five ladies sitting in a second line parallel to the first line and are facing to North. B who is just next to the left of D, is opposite to Q. C and N are diagonally opposite to each other. E is opposite to O who is just next right of M. P who is just to the left of Q, is opposite to D. 6. M is at one end of the line If B shifts to the place of E, E shifts to the place of Q, and Q shifts to the place of B, then who will be the second to the left of the person opposite to O ?
Answer» Each of these questions are based on the information given below: A ,B, C, D and E are five men sitting in a line facing to south - while M, N, O, P and Q are five ladies sitting in a second line parallel to the first line and are facing to North. B who is just next to the left of D, is opposite to Q. C and N are diagonally opposite to each other. E is opposite to O who is just next right of M. P who is just to the left of Q, is opposite to D. 6. M is at one end of the line If B shifts to the place of E, E shifts to the place of Q, and Q shifts to the place of B, then who will be the second to the left of the person opposite to O ?

35.

Each of these questions are based on the information given below: A ,B, C, D and E are five men sitting in a line facing to south - while M, N, O, P and Q are five ladies sitting in a second line parallel to the first line and are facing to North. B who is just next to the left of D, is opposite to Q. C and N are diagonally opposite to each other. E is opposite to O who is just next right of M. P who is just to the left of Q, is opposite to D. 6. M is at one end of the line If B shifts to the place of E, E shifts to the place of Q, and Q shifts to the place of B, then who will be the second to the left of the person opposite to O ?

Answer»

Each of these questions are based on the information given below:

A ,B, C, D and E are five men sitting in a line facing to south - while M, N, O, P and Q are five ladies sitting in a second line parallel to the first line and are facing to North. B who is just next to the left of D, is opposite to Q. C and N are diagonally opposite to each other. E is opposite to O who is just next right of M. P who is just to the left of Q, is opposite to D.

6. M is at one end of the line

If B shifts to the place of E, E shifts to the place of Q, and Q shifts to the place of B, then who will be the second to the left of the person opposite to O ?

Discussion

36.	Assume that each iron atom has a permanent magnetic moment equal to 'a' A-m2. Density of atoms in iron is n atoms/m3. Then maximum magnetic field B on the axis inside long cylinder of iron can be
Answer» Assume that each iron atom has a permanent magnetic moment equal to 'a' A- $m^{2}$ . Density of atoms in iron is n atoms/ $m^{3}$ . Then maximum magnetic field B on the axis inside long cylinder of iron can be

Discussion

37.	Consider a body shown in the figure below, consisting of two identical balls, each of mass 'M' connected by a light rigid rod of length 'L'. If an impulse, J = Mv is imparted to the body at one of its ends, what would be its angular velocity?
Answer» Consider a body shown in the figure below, consisting of two identical balls, each of mass 'M' connected by a light rigid rod of length 'L'. If an impulse, J = Mv is imparted to the body at one of its ends, what would be its angular velocity?

Discussion

38.	Refractive index of glass with respect to water is 1.125. If the absolute refractive index of glass is 1.5, find the absolute refractive index of water.
Answer» Refractive index of glass with respect to water is 1.125. If the absolute refractive index of glass is 1.5, find the absolute refractive index of water.

Discussion

39.	Two discs of radii 4 cm and 2 cm respectively are attached as shown in the figure. The distance of the new centre of mass of the system from C1 is
Answer» Two discs of radii $4 cm$ and $2 cm$ respectively are attached as shown in the figure. The distance of the new centre of mass of the system from $C_{1}$ is

Discussion

40.	A simple pendulum has period T inside a lift when it is stationary. The lift is accelerated upwards with constant acceleration a. The period
Answer» A simple pendulum has period T inside a lift when it is stationary. The lift is accelerated upwards with constant acceleration a. The period

Discussion

41.	A 30 kg block rests on a rough horizontal surface. A horizontal force of 200 N is applied on the body. The block acquires a speed of 4 m/sec, starting from rest, in 2 sec. What is the value of coefficient of friction?
Answer» A $30 kg$ block rests on a rough horizontal surface. A horizontal force of $200 N$ is applied on the body. The block acquires a speed of $4 m/sec$ , starting from rest, in $2 sec$ . What is the value of coefficient of friction?

Discussion

42.	Consider a particle of mass m suspended vertically by a string at the equator. Let R and M denote the radius and the mass of the earth respectively. If ω is the angular velocity of earth's rotation about its own axis, the tension in the string is equal to
Answer» Consider a particle of mass m suspended vertically by a string at the equator. Let R and M denote the radius and the mass of the earth respectively. If $ω$ is the angular velocity of earth's rotation about its own axis, the tension in the string is equal to

Discussion

43.	In the adjoining ray-diagram are given the positions of an object O, image I and two lenses L1 and L2. The focal length of L1 is also given. Find the focal length of the lens L2.
Answer» In the adjoining ray-diagram are given the positions of an object $O$ , image $I$ and two lenses $L_{1}$ and $L_{2}$ . The focal length of $L_{1}$ is also given. Find the focal length of the lens $L_{2}$ .

Discussion

44.	At a certain temperature, the r.m.s velocity for O2 is 400 m/sec. At the same temperature, the r.m.s velocity for H2 molecules will be
Answer» At a certain temperature, the r.m.s velocity for $O_{2}$ is 400 m/sec. At the same temperature, the r.m.s velocity for $H_{2}$ molecules will be

Discussion

45.	Two cars, initially at a separation of 12 m, start simultaneously. First car "A", starting from rest, moves with an acceleration 2 m/s2, whereas the car "B" which is ahead, moves with a constant velocity 1 m/s along the same direction. Find the time when the car "A" overtakes car "B".
Answer» Two cars, initially at a separation of $12 m$ , start simultaneously. First car " $A$ ", starting from rest, moves with an acceleration $2 {m/s}^{2}$ , whereas the car " $B$ " which is ahead, moves with a constant velocity $1 m/s$ along the same direction. Find the time when the car " $A$ " overtakes car " $B$ ".

Discussion

46.	The conductivity of a pure semiconductor is roughly proportional to T3/2 e−ΔE/2KT where ΔE is the band gap. The band gap for germanium is 0.74 eV at 4 K and 0.67 eV at 300 K. By what factor does the conductivity of pure germanium increase as the temperature is raised from 4 K to 300 K ?
Answer» The conductivity of a pure semiconductor is roughly proportional to $T^{3 / 2} e^{- Δ E / 2 K T}$ where $Δ E$ is the band gap. The band gap for germanium is 0.74 eV at 4 K and 0.67 eV at 300 K. By what factor does the conductivity of pure germanium increase as the temperature is raised from 4 K to 300 K ?

Discussion

47.	Does the principle of superposition hold good in the case of very strong electric forces?
Answer» Does the principle of superposition hold good in the case of very strong electric forces?

Discussion

48.	A symmetric biconvex lens of radius of curvature R and made of glass of refractive index 1.5, is placed on a layer of liquid placed on top of a plane mirror as shown in the figure. An optical needle with its tip on the principal axis of the lens is moved along the axis until its real, inverted image coincides with the needle itslelf. The distance of the needle from the lens is measured to be x. On removing the liquid layer and repeating the experiment, the distance is found to be y. Obtain the expression for the refractive index of the liquid in terms of x and y.
Answer» A symmetric biconvex lens of radius of curvature R and made of glass of refractive index 1.5, is placed on a layer of liquid placed on top of a plane mirror as shown in the figure. An optical needle with its tip on the principal axis of the lens is moved along the axis until its real, inverted image coincides with the needle itslelf. The distance of the needle from the lens is measured to be x. On removing the liquid layer and repeating the experiment, the distance is found to be y. Obtain the expression for the refractive index of the liquid in terms of x and y.

Discussion

49.	A short bar magnet is placed in a uniform magnetic field. To maintain equilibrium when it makes angle 60∘with external field, we need to apply a torque of 40√3 Nm. Find the potential energy of the magnet.
Answer» A short bar magnet is placed in a uniform magnetic field. To maintain equilibrium when it makes angle $60^{\circ}$ with external field, we need to apply a torque of $40 \sqrt{3} N m$ . Find the potential energy of the magnet.

Discussion

50.	The fraction of atoms of radioactive element that decays in 6 days is 78. The fraction that decays in 10 days will be
Answer» The fraction of atoms of radioactive element that decays in 6 days is $\frac{7}{8}$ . The fraction that decays in 10 days will be

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

In Young’s double slit experiment, the aperture screen distance is 2 m. The fringe width is 1 mm. Light of 600 nm is used. If a thin plate of glass (μ=1.5) of thickness 0.06 mm is placed over one of the slit, then there will be a lateral displacement of the fringe by:

A stone is placed at the bottom of lake of depth 10 m. Refractive index of water of lake is μ=(1+y10) where 'y' is depth of water from surface. A person looks at stone normally, then depth at which stone appears to him in meters is (ln 2 = 0.693). Write upto two digits after the decimal point.

According to Newton’s first law of motion, force is necessary to

The electric and magnetic fields produced by the radiation coming from a 100 W bulb at a distance of 3m is respectively [Assume that the efficiency of the bulb is 2.5% and it is a point source]

A 100 W bulb B1, and two 60 W bulbs B2 and B3, are connected to a 250 V source as shown in the figure. Now W1,W2 and W3 are the output powers of the bulbs B1,B2 and B3 respectively. Then

Assuming steady state one-dimensional heat conduction in a composite slab, if Tinter=T1+T22, then which of the following statements is true about the respective thermal conductivities?

A stretched sonometer wire resonates at a frequency of 350 Hz and at the next higher frequency of 420 Hz. The fundamental frequency of this wire is :

The pressure and density of a diatomic gas (γ=75) change adiabatically form (p1,d1) to (p2,d2). If d2d1=32, then p2p1 is

A ball is projected from point A with velocity 10 m/s perpendicular to the inclined plane as shown in figure. Range of the ball on the inclined plane is equal to N3 m. Then, N is equal to

Find the acceleration of the particle at x=3 m.

A body is projected vertically upwards from the bottom of a crater of moon of depth R100 where R is the radius of moon with a velocity equal to the escape velocity on the surface of moon. Maximum height attained by the body from the surface of the moon is KR.The value of K is

The binding energy per nucleon of 21H and 42He are 1.1 MeV and 7.0 MeV respectively. Energy released in the process 21H+21H→42He is

Derive relationship between Moment of inertia , angular velocity and torque

In J.J. Thomson’s method, electric field E, magnetic field B and velocity v of the electron were in mutually perpendicular direction. This velocity selector allows particles of velocity v to pass undeflected when (correct answer + 1, wrong answer - 0.25)

120 g of ice at 0∘C is mixed with 100 g of water at 80∘C . Latent heat of fusion is 80 cal/g and specific heat of water is 1 cal/g∘C. The final temperature of the mixture is (correct answer + 1, wrong answer - 0.25)

Consider a wheel purely rolling on a rough horizontal surface with constant velocity v. Radius of the wheel is R and C is the center of wheel. M is top-most point, P is bottom-most point and N is in level with C at any time. Match the columns for this instant of time.

Is there a condition that if velocity is positive,acceleration should be negative?

A particle performing SHM has a velocity v0 at mean position. Find the velocity of the particle, when it reaches a point which is at a distance A2 from the mean position. [A= amplitude of SHM]

Two Radioactive substances X and Y emit α and β particles respectively. Their disintegration constants are in the ratio 2 : 3. To have equal rate of disintegration of getting emission of α and β particles., the ratio of number of atoms of X to that of Y at any time instant is

Figure represents a glass plate placed vertically on a horizontal table with a beam of unpolarised light falling on its surface at the polarizing angle of 57∘ with the normal. The electric vector in the reflected light on screen S will vibrate with respect to the plane of incidence in a

Two disc of same radius (r) and mass (m) are placed such that their centre is at a common point and their planes are perpendicular to each other. The moment of inertia of the system about an axis passing through the centre and perpendicular to plane of one of the discs is:

Why rolling friction is less than sliding friction?

A certain prism is found to produce a minimum deviation of 38∘. It produces a deviation of 44∘ when the angle of incidence is either 42∘ or 62∘ . What is the angle of incidence when it is undergoing minimum deviation?

A body of mass m accelerates uniformly from rest to v1 in time t1. The instantaneous power delivered to the body as a function of time t is

Transverse waves are generated in two uniform steel wires A and B when a source of frequency 500 Hz is attached to their free-ends. The diameter of A is half that of B and the tension in A is half that in B. The ratio of the velocity of the waves in wires A and B is

A capillary tube A is dipped in water. Another identical tube B is dipped in a soap - water solution. Which of the following shows the relative nature of the liquid columns in the two tubes?

Q27) Which of the following book was not authored by Late Avul Pakir Jainulabdeen Abdul Kalam the Former Indian President who passed away recently?​

How can we say ions like Helium , beryllium,etc are hydrogen like sprcies.? Pls explain.

Light of wavelength 5.0×10−7 m falls on a pair of narrow slits separated by a distance d. The interference pattern on a screen placed 2.0 m away shows that there is first dark fringe at the positions exactly opposite to each slit. The separation between the slits is:

A man is 180 cm tall and his eyes are 10 cm below the top of his head. In order to see this entire height right from toe to head, he uses a plane mirror kept at a distance of 1 m from him. The minimum length of the plane mirror is

Assume that each iron atom has a permanent magnetic moment equal to 'a' A-m2. Density of atoms in iron is n atoms/m3. Then maximum magnetic field B on the axis inside long cylinder of iron can be

Consider a body shown in the figure below, consisting of two identical balls, each of mass 'M' connected by a light rigid rod of length 'L'. If an impulse, J = Mv is imparted to the body at one of its ends, what would be its angular velocity?

Refractive index of glass with respect to water is 1.125. If the absolute refractive index of glass is 1.5, find the absolute refractive index of water.

Two discs of radii 4 cm and 2 cm respectively are attached as shown in the figure. The distance of the new centre of mass of the system from C1 is

A simple pendulum has period T inside a lift when it is stationary. The lift is accelerated upwards with constant acceleration a. The period

A 30 kg block rests on a rough horizontal surface. A horizontal force of 200 N is applied on the body. The block acquires a speed of 4 m/sec, starting from rest, in 2 sec. What is the value of coefficient of friction?

Consider a particle of mass m suspended vertically by a string at the equator. Let R and M denote the radius and the mass of the earth respectively. If ω is the angular velocity of earth's rotation about its own axis, the tension in the string is equal to

In the adjoining ray-diagram are given the positions of an object O, image I and two lenses L1 and L2. The focal length of L1 is also given. Find the focal length of the lens L2.

At a certain temperature, the r.m.s velocity for O2 is 400 m/sec. At the same temperature, the r.m.s velocity for H2 molecules will be

Two cars, initially at a separation of 12 m, start simultaneously. First car "A", starting from rest, moves with an acceleration 2 m/s2, whereas the car "B" which is ahead, moves with a constant velocity 1 m/s along the same direction. Find the time when the car "A" overtakes car "B".

The conductivity of a pure semiconductor is roughly proportional to T3/2 e−ΔE/2KT where ΔE is the band gap. The band gap for germanium is 0.74 eV at 4 K and 0.67 eV at 300 K. By what factor does the conductivity of pure germanium increase as the temperature is raised from 4 K to 300 K ?

Does the principle of superposition hold good in the case of very strong electric forces?

A short bar magnet is placed in a uniform magnetic field. To maintain equilibrium when it makes angle 60∘with external field, we need to apply a torque of 40√3 Nm. Find the potential energy of the magnet.

The fraction of atoms of radioactive element that decays in 6 days is 78. The fraction that decays in 10 days will be

Q27) Which of the following book was not authored by Late Avul Pakir Jainulabdeen Abdul Kalam the Former Indian President who passed away recently?