50278 + Interview Questions in Physics

1.	Image of sun formed due to reflection at air water interface is found to be very highly polarised. Refractive index of water being μ=4/3, find the angle of sun above the horizon.
Answer» Image of sun formed due to reflection at air water interface is found to be very highly polarised. Refractive index of water being $μ = 4 / 3$ , find the angle of sun above the horizon.

Discussion

2.	Find the current through Ω resistance:
Answer» Find the current through $Ω$ resistance:

2.

Find the current through Ω resistance:

Answer»

Find the current through $Ω$ resistance:

Discussion

3.	Explain the difference between polar and non-polar dielectric materials.
Answer» Explain the difference between polar and non-polar dielectric materials.

Discussion

4.	A simple pendulum 50 cm long is suspended from the roof of a cart accelerating in the horizontal direction with constant acceleration of √3g m/s2. The period of small oscillations of the pendulum about its equilibrium position is - (g=π2 m/s2)
Answer» A simple pendulum $50 cm$ long is suspended from the roof of a cart accelerating in the horizontal direction with constant acceleration of $\sqrt{3} g {m/s}^{2}$ . The period of small oscillations of the pendulum about its equilibrium position is - $(g = π^{2} {m/s}^{2})$

Discussion

5.	In a heated tennis match Nadal returns the ball straight to Federer at 40 m/s speed. Federer returns the ball straight back to Nadal at 30 m/s. Given the mass of ball to be 12 kg, find the impulse with which Federer returned the ball?
Answer» In a heated tennis match Nadal returns the ball straight to Federer at 40 m/s speed. Federer returns the ball straight back to Nadal at 30 m/s. Given the mass of ball to be 12 kg, find the impulse with which Federer returned the ball?

Discussion

6.	The ratio of the terminal velocities of two drops of same density of radii R and R/2 in air is
Answer» The ratio of the terminal velocities of two drops of same density of radii $R$ and $R / 2$ in air is

Discussion

7.	What are the SI unit and dimensional formula of the coefficient of viscosity?
Answer» What are the SI unit and dimensional formula of the coefficient of viscosity?

Discussion

8.	If θ depends on time t as θ=2t2+3, find the average angular velocity at the end of 3 sec and instantaneous angular velocity at t=3 sec (in rad/s)
Answer» If $θ$ depends on time $t$ as $θ = 2 t^{2} + 3$ , find the average angular velocity at the end of $3 sec$ and instantaneous angular velocity at $t = 3 sec$ (in $r a d / s$ )

Discussion

9.	A boat moves relative to water with a velocity v and river is flowing with 2v. At what angle with the stream should the boat move to have minimum drift?
Answer» A boat moves relative to water with a velocity $v$ and river is flowing with $2 v$ . At what angle with the stream should the boat move to have minimum drift?

Discussion

10.	If →a=^i+^j and →b=−^j+2^k. Find (→a−→b).(→a+2→b).
Answer» If $\to a =^i +^j$ and $\to b = -^j + 2^k$ . Find $(\to a - \to b) . (\to a + 2 \to b)$ .

Discussion

11.	Refractive index for a material of infrared light is?
Answer» Refractive index for a material of infrared light is?

11.

Refractive index for a material of infrared light is?

Answer»

Refractive index for a material of infrared light is?

Discussion

12.	How gravitational force is conservative force!???
Answer» How gravitational force is conservative force!???

Discussion

13.	If only one charge is available can it itself be used to obtain a charge many times greater than itself in magnitude?
Answer» If only one charge is available can it itself be used to obtain a charge many times greater than itself in magnitude?

Discussion

14.	A spherical ball A of surface area 20 cm2 is kept at the centre of a hollow spherical shell B of area 80 cm2. The surface of A and the inner surface of B emit as blackbodies. Assume that the thermal conductivity of the material of B is extremely poor and that of A is very high and that the air between A and B has been pumped out. The heat capacities of A and B are 42 J/∘C and 82 J/ ∘ C respectively. Initially the temperature of A is 100 ∘ C and that of B is 20 ∘ C.Find the rate of change of temperature of A and that of B at this instant.
Answer» A spherical ball A of surface area 20 $c m^{2}$ is kept at the centre of a hollow spherical shell B of area 80 $c m^{2}$ . The surface of A and the inner surface of B emit as blackbodies. Assume that the thermal conductivity of the material of B is extremely poor and that of A is very high and that the air between A and B has been pumped out. The heat capacities of A and B are 42 J/ $^{\circ}$ C and 82 J/ $^{\circ}$ C respectively. Initially the temperature of A is 100 $^{\circ}$ C and that of B is 20 $^{\circ}$ C.Find the rate of change of temperature of A and that of B at this instant.

Discussion

15.	A metallic sphere floats in an immiscible mixture of water (density 103 kg/m3) and a liquid (density 8×103kg/m3) such that its (23) part is in water and (13) part in the liquid. The density of the metal is
Answer» A metallic sphere floats in an immiscible mixture of water (density 10 $^{3}$ kg/m $^{3}$ ) and a liquid (density $8 \times 10^{3} k g / m^{3}$ ) such that its ( $\frac{2}{3}$ ) part is in water and ( $\frac{1}{3}$ ) part in the liquid. The density of the metal is

Discussion

16.	Find the following integrals. ∫√x(3x2+2x+3)dx.
Answer» Find the following integrals. $\int \sqrt{x} (3 x^{2} + 2 x + 3) d x .$

Discussion

17.	A projectile is fired from the top of a 40 m height cliff with an initial speed of 50 m/s at an unknown angle. Find its speed when it hits the ground.
Answer» A projectile is fired from the top of a $40 m$ height cliff with an initial speed of $50 m/s$ at an unknown angle. Find its speed when it hits the ground.

Discussion

18.	A rod of length 1000 mm and coefficient of linear expansion α=10−4/∘C is placed symmetrically between fixed walls separated by 1001 mm. The Young’s modulus of the rod is 1011Nm2 If the temperature is increased by 20∘C, then the stress developed in the rod (in MPa) is
Answer» A rod of length $1000 m m$ and coefficient of linear expansion $α = 10^{- 4} /^{\circ} C$ is placed symmetrically between fixed walls separated by $1001 m m$ . The Young’s modulus of the rod is $10^{11} \frac{N}{m^{2}}$ If the temperature is increased by $20^{\circ} C$ , then the stress developed in the rod (in $M P a$ ) is

Discussion

19.	Lines of force originate and terminate on a conductor.Why?
Answer» Lines of force originate and terminate on a conductor.Why?

Discussion

20.	One mole of an ideal monoatomic gas is taken at a temperature of 300 K. If the volume is doubled keeping its pressure constant, change in internal energy is
Answer» One $mole$ of an ideal monoatomic gas is taken at a temperature of $300 K$ . If the volume is doubled keeping its pressure constant, change in internal energy is

Discussion

21.	If the unit of force is 100N, unit of length is 10m and unit of time is 100s ,what is the unit of mass in this system of units?
Answer» If the unit of force is 100N, unit of length is 10m and unit of time is 100s ,what is the unit of mass in this system of units?

Discussion

22.	How many words can be made from the letters of the word COMMITTEE
Answer» How many words can be made from the letters of the word COMMITTEE

Discussion

23.	A man wishes to cross a river in a Boat if he crosses the river in minimum time it takes 10 minutes with a drift of 120 m. if he crosses the river taking shortest route he takes 12.5 minutes find the velocity of boat .
Answer» A man wishes to cross a river in a Boat if he crosses the river in minimum time it takes 10 minutes with a drift of 120 m. if he crosses the river taking shortest route he takes 12.5 minutes find the velocity of boat .

Discussion

24.	The maximum range of a gun on horizontal terrain is 16 km. If g=10 m/s2. What must be the muzzle velocity of the shell
Answer» The maximum range of a gun on horizontal terrain is 16 km. If $g = 10 m / s^{2}$ . What must be the muzzle velocity of the shell

Discussion

25.	A body of mass 10 kg at rest is acted upon simultaneously by two forces 4N and 3N at right angles to each other. The kinetic energy of the body at the end of 10 sec is
Answer» A body of mass 10 kg at rest is acted upon simultaneously by two forces 4N and 3N at right angles to each other. The kinetic energy of the body at the end of 10 sec is

Discussion

26.	A bullet of mass 0.01 kg travelling at a speed of 500 m/s strikes a block of mass 2 kg which is suspended by a string of length 5 m. The centre of gravity of the block is found to rise a vertical distance of 0.2 m. What is the speed of the bullet after it emerges from the block?
Answer» A bullet of mass 0.01 kg travelling at a speed of 500 m/s strikes a block of mass 2 kg which is suspended by a string of length 5 m. The centre of gravity of the block is found to rise a vertical distance of 0.2 m. What is the speed of the bullet after it emerges from the block?

Discussion

27.	A stretched string of 1m length and mass 5×10−4 Kg is having tension of 20N. If it is plucked at 25cm from one end then it will vibrate with frequency [RPET 1999; RPMT 2002]
Answer» A stretched string of 1m length and mass $5 \times 10^{- 4}$ Kg is having tension of 20N. If it is plucked at 25cm from one end then it will vibrate with frequency [RPET 1999; RPMT 2002]

27.

A stretched string of 1m length and mass 5×10−4 Kg is having tension of 20N. If it is plucked at 25cm from one end then it will vibrate with frequency [RPET 1999; RPMT 2002]

Answer»

A stretched string of 1m length and mass $5 \times 10^{- 4}$ Kg is having tension of 20N.

If it is plucked at 25cm from one end then it will vibrate with frequency

[RPET 1999; RPMT 2002]

Discussion

28.	The free body diagram of a car moving on the banked road is
Answer» The free body diagram of a car moving on the banked road is

Discussion

29.	A hollow cylindrical pipe of length 10 cm has inner radius r1=3 cm and outer radius r2=12 cm. The temperature difference between the inner and outer layer of cylindrical pipe is 100∘C and the thermal conductivity of cylindrical pipe is 150 W/m∘C. Find the rate of heat transfered (in kW) between inner and outer layers. (Take ln2=0.693)
Answer» A hollow cylindrical pipe of length $10 cm$ has inner radius $r_{1} = 3 cm$ and outer radius $r_{2} = 12 cm$ . The temperature difference between the inner and outer layer of cylindrical pipe is $100^{\circ} C$ and the thermal conductivity of cylindrical pipe is $150 {W/m}^{\circ} C$ . Find the rate of heat transfered (in $kW$ ) between inner and outer layers. (Take $ln 2 = 0.693$ )

Discussion

30.	As shown in figure, all the surfaces are frictionless and the pulleys and the string are light. The magnitude of acceleration of block 2M is
Answer» As shown in figure, all the surfaces are frictionless and the pulleys and the string are light. The magnitude of acceleration of block $2 M$ is

Discussion

31.	A block of mass m is placed on a surface with a vertical cross-section given by y=x36. If the coefficient of friction is 0.5, the maximum height above the ground at which the block can be placed without slipping is
Answer» A block of mass m is placed on a surface with a vertical cross-section given by $y = \frac{x^{3}}{6}$ . If the coefficient of friction is 0.5, the maximum height above the ground at which the block can be placed without slipping is

Discussion

32.	A stone tied to an inextensible string of length l=1 m is kept horizontal. If it is released, find the angular speed (rad/s) of the stone when the string makes an angle θ=30∘ with horizontal.
Answer» A stone tied to an inextensible string of length $l = 1 m$ is kept horizontal. If it is released, find the angular speed (rad/s) of the stone when the string makes an angle $θ = 30^{\circ}$ with horizontal.

Discussion

33.	A bullet of mass 20g travelling horizontally with a speed of 500 m/s passes through a wooden block of mass 10.0 kg initially at rest on a level surface. The bullet emerges with a speed of 100 m/s and the block slides 20 cm on the surface before coming to rest. The friction coefficient between the block and the surface is g=10 ms−2
Answer» A bullet of mass 20g travelling horizontally with a speed of 500 m/s passes through a wooden block of mass 10.0 kg initially at rest on a level surface. The bullet emerges with a speed of 100 m/s and the block slides 20 cm on the surface before coming to rest. The friction coefficient between the block and the surface is $g = 10 m s^{- 2}$

Discussion

34.	A 20 N force displaces a body by 10 m. The angle between force and direction of displacement is 60°. Calculate the work done.
Answer» A 20 N force displaces a body by 10 m. The angle between force and direction of displacement is 60°. Calculate the work done.

Discussion

35.	A car travels first half distance between two places with uniform speed of 60 km/hr. What should be its uniform speed (in km/hr) for the second half of the distance so that its average speed over the entire journey becomes 90 km/hr.
Answer» A car travels first half distance between two places with uniform speed of $60 km/hr$ . What should be its uniform speed (in $km/hr$ ) for the second half of the distance so that its average speed over the entire journey becomes $90 km/hr$ .

Discussion

36.	What is the nature of current around the conductor
Answer» What is the nature of current around the conductor

Discussion

37.	When a metallic surface is illuminated by a light of wavelength λ the stopping potential for the photoelectric current is 3 V. When the same surface is illuminated by light of wavelength 2λ the stopping potential is 1 V. The threshold wavelength of this surface is
Answer» When a metallic surface is illuminated by a light of wavelength $λ$ the stopping potential for the photoelectric current is 3 V. When the same surface is illuminated by light of wavelength $2 λ$ the stopping potential is 1 V. The threshold wavelength of this surface is

Discussion

38.	A wooden bowl conducts less heat than a copper bowl because
Answer» A wooden bowl conducts less heat than a copper bowl because

Discussion

39.	The factor not needed to calculate heat lost or gained when there is no change of state is
Answer» The factor not needed to calculate heat lost or gained when there is no change of state is

Discussion

40.	Careful measurement of the electric field at the surface of a black box indicates that the net outward flux through the surface of the box is 8.0×103 Nm2/C. What is the net charge inside the box? If the net outward flux through the surface of the box were zero, could you conclude that there were no charges inside the box? Why or Why not?
Answer» Careful measurement of the electric field at the surface of a black box indicates that the net outward flux through the surface of the box is $8.0 \times 10^{3} N m^{2} / C .$ What is the net charge inside the box? If the net outward flux through the surface of the box were zero, could you conclude that there were no charges inside the box? Why or Why not?

40.

Careful measurement of the electric field at the surface of a black box indicates that the net outward flux through the surface of the box is 8.0×103 Nm2/C. What is the net charge inside the box? If the net outward flux through the surface of the box were zero, could you conclude that there were no charges inside the box? Why or Why not?

Answer»

Careful measurement of the electric field at the surface of a black
box indicates that the net outward flux through the surface of the
box is $8.0 \times 10^{3} N m^{2} / C .$
What is the net charge inside the box?

If the net outward flux through the surface of the box were zero,
could you conclude that there were no charges inside the box? Why
or Why not?

Discussion

41.	A parallel plate capacitor of plate separation d, plate area A and of capacitance C is charged to a potential difference V by connecting it to a battery. When a dielectric slab of thickness t and k = 2 is introduced between the plates of the capacitor, its capacitance increases to 32C, the ratio td is
Answer» A parallel plate capacitor of plate separation d, plate area A and of capacitance C is charged to a potential difference V by connecting it to a battery. When a dielectric slab of thickness t and k = 2 is introduced between the plates of the capacitor, its capacitance increases to $\frac{3}{2} C$ , the ratio $\frac{t}{d}$ is

Discussion

42.	Two mercury drops each of radius r merge to form a bigger drop. The surface energy of the bigger drop, if T is the surface tension of mercury, is
Answer» Two mercury drops each of radius $r$ merge to form a bigger drop. The surface energy of the bigger drop, if $T$ is the surface tension of mercury, is

Discussion

43.	A point object O is moving with a velocity of v in front of an arrangement of plane mirrors as shown in the figure. The magnitude of velocity of image in mirror M1 with respect to the image in mirror M2 will be
Answer» A point object $O$ is moving with a velocity of $v$ in front of an arrangement of plane mirrors as shown in the figure. The magnitude of velocity of image in mirror $M_{1}$ with respect to the image in mirror $M_{2}$ will be

Discussion

44.	A gas is in equilibrium at T kelvin. Mass of one molecule is m and, its component of velocity in x direction is vx. The mean of its v2x is represented by nkTm. Find n.
Answer» A gas is in equilibrium at $T$ kelvin. Mass of one molecule is $m$ and, its component of velocity in $x$ direction is $v_{x}$ . The mean of its $v_{x}^{2}$ is represented by $\frac{n k T}{m}$ . Find $n$ .

Discussion

45.	Will an emf be induced in a conductor moving parallel to the magnetic field?
Answer» Will an emf be induced in a conductor moving parallel to the magnetic field?

Discussion

46.	Figure shows a container filled with a liquid of density ρ. Four points A, B, C and D lies on the vertices of a vertical square. Points A and C lies on a vertical line and points B and D lies on a horizontal line. Choose the correct statement(s) about the pressure at the four points.
Answer» Figure shows a container filled with a liquid of density $ρ$ . Four points $A, B, C$ and $D$ lies on the vertices of a vertical square. Points $A$ and $C$ lies on a vertical line and points $B$ and $D$ lies on a horizontal line. Choose the correct statement(s) about the pressure at the four points.

Discussion

47.	One mole of an ideal monoatomic gas has initial temperature T0 is made to go through the cyclic process abca as shown in figure. If U denotes the internal energy, then choose the correct alternative.
Answer» One mole of an ideal monoatomic gas has initial temperature $T_{0}$ is made to go through the cyclic process $a b c a$ as shown in figure. If $U$ denotes the internal energy, then choose the correct alternative.

Discussion

48.	Find the moment of inertia I of hollow sphere of outer radius R=20 cm and mass M=1 kg about its tangent on outer surface.
Answer» Find the moment of inertia $I$ of hollow sphere of outer radius $R = 20 cm$ and mass $M = 1 kg$ about its tangent on outer surface.

Discussion

49.	The maximum number of possible interference maxima for slit- separation equal to thrice the wavelength in Young's double slit experiment is
Answer» The maximum number of possible interference maxima for slit- separation equal to thrice the wavelength in Young's double slit experiment is

Discussion

50.	For a certain organ pipe, three successive resonance frequencies are observed at 425 Hz, 595 Hz and 765 Hz respectively. The fundamental frequency of the pipe is - [speed of sound in air =340 m/s ]
Answer» For a certain organ pipe, three successive resonance frequencies are observed at $425 Hz$ , $595 Hz$ and $765 Hz$ respectively. The fundamental frequency of the pipe is - $[$ speed of sound in air $= 340 m/s]$

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Image of sun formed due to reflection at air water interface is found to be very highly polarised. Refractive index of water being μ=4/3, find the angle of sun above the horizon.

Find the current through Ω resistance:

Explain the difference between polar and non-polar dielectric materials.

A simple pendulum 50 cm long is suspended from the roof of a cart accelerating in the horizontal direction with constant acceleration of √3g m/s2. The period of small oscillations of the pendulum about its equilibrium position is - (g=π2 m/s2)

In a heated tennis match Nadal returns the ball straight to Federer at 40 m/s speed. Federer returns the ball straight back to Nadal at 30 m/s. Given the mass of ball to be 12 kg, find the impulse with which Federer returned the ball?

The ratio of the terminal velocities of two drops of same density of radii R and R/2 in air is

What are the SI unit and dimensional formula of the coefficient of viscosity?

If θ depends on time t as θ=2t2+3, find the average angular velocity at the end of 3 sec and instantaneous angular velocity at t=3 sec (in rad/s)

A boat moves relative to water with a velocity v and river is flowing with 2v. At what angle with the stream should the boat move to have minimum drift?

If →a=^i+^j and →b=−^j+2^k. Find (→a−→b).(→a+2→b).

Refractive index for a material of infrared light is?

How gravitational force is conservative force!???

If only one charge is available can it itself be used to obtain a charge many times greater than itself in magnitude?

A metallic sphere floats in an immiscible mixture of water (density 103 kg/m3) and a liquid (density 8×103kg/m3) such that its (23) part is in water and (13) part in the liquid. The density of the metal is

Find the following integrals. ∫√x(3x2+2x+3)dx.

A projectile is fired from the top of a 40 m height cliff with an initial speed of 50 m/s at an unknown angle. Find its speed when it hits the ground.

A rod of length 1000 mm and coefficient of linear expansion α=10−4/∘C is placed symmetrically between fixed walls separated by 1001 mm. The Young’s modulus of the rod is 1011Nm2 If the temperature is increased by 20∘C, then the stress developed in the rod (in MPa) is

Lines of force originate and terminate on a conductor.Why?

One mole of an ideal monoatomic gas is taken at a temperature of 300 K. If the volume is doubled keeping its pressure constant, change in internal energy is

If the unit of force is 100N, unit of length is 10m and unit of time is 100s ,what is the unit of mass in this system of units?

How many words can be made from the letters of the word COMMITTEE

A man wishes to cross a river in a Boat if he crosses the river in minimum time it takes 10 minutes with a drift of 120 m. if he crosses the river taking shortest route he takes 12.5 minutes find the velocity of boat .

The maximum range of a gun on horizontal terrain is 16 km. If g=10 m/s2. What must be the muzzle velocity of the shell

A body of mass 10 kg at rest is acted upon simultaneously by two forces 4N and 3N at right angles to each other. The kinetic energy of the body at the end of 10 sec is

A bullet of mass 0.01 kg travelling at a speed of 500 m/s strikes a block of mass 2 kg which is suspended by a string of length 5 m. The centre of gravity of the block is found to rise a vertical distance of 0.2 m. What is the speed of the bullet after it emerges from the block?

A stretched string of 1m length and mass 5×10−4 Kg is having tension of 20N. If it is plucked at 25cm from one end then it will vibrate with frequency [RPET 1999; RPMT 2002]

The free body diagram of a car moving on the banked road is

As shown in figure, all the surfaces are frictionless and the pulleys and the string are light. The magnitude of acceleration of block 2M is

A block of mass m is placed on a surface with a vertical cross-section given by y=x36. If the coefficient of friction is 0.5, the maximum height above the ground at which the block can be placed without slipping is

A stone tied to an inextensible string of length l=1 m is kept horizontal. If it is released, find the angular speed (rad/s) of the stone when the string makes an angle θ=30∘ with horizontal.

A 20 N force displaces a body by 10 m. The angle between force and direction of displacement is 60°. Calculate the work done.

A car travels first half distance between two places with uniform speed of 60 km/hr. What should be its uniform speed (in km/hr) for the second half of the distance so that its average speed over the entire journey becomes 90 km/hr.

What is the nature of current around the conductor

When a metallic surface is illuminated by a light of wavelength λ the stopping potential for the photoelectric current is 3 V. When the same surface is illuminated by light of wavelength 2λ the stopping potential is 1 V. The threshold wavelength of this surface is

A wooden bowl conducts less heat than a copper bowl because

The factor not needed to calculate heat lost or gained when there is no change of state is

Two mercury drops each of radius r merge to form a bigger drop. The surface energy of the bigger drop, if T is the surface tension of mercury, is

A point object O is moving with a velocity of v in front of an arrangement of plane mirrors as shown in the figure. The magnitude of velocity of image in mirror M1 with respect to the image in mirror M2 will be

A gas is in equilibrium at T kelvin. Mass of one molecule is m and, its component of velocity in x direction is vx. The mean of its v2x is represented by nkTm. Find n.

Will an emf be induced in a conductor moving parallel to the magnetic field?

Figure shows a container filled with a liquid of density ρ. Four points A, B, C and D lies on the vertices of a vertical square. Points A and C lies on a vertical line and points B and D lies on a horizontal line. Choose the correct statement(s) about the pressure at the four points.

One mole of an ideal monoatomic gas has initial temperature T0 is made to go through the cyclic process abca as shown in figure. If U denotes the internal energy, then choose the correct alternative.

Find the moment of inertia I of hollow sphere of outer radius R=20 cm and mass M=1 kg about its tangent on outer surface.

The maximum number of possible interference maxima for slit- separation equal to thrice the wavelength in Young's double slit experiment is

For a certain organ pipe, three successive resonance frequencies are observed at 425 Hz, 595 Hz and 765 Hz respectively. The fundamental frequency of the pipe is - [speed of sound in air =340 m/s ]