50278 + Interview Questions in Physics

1.	Consider a sphere of radius R having charge q uniformly distributed inside it. At what minimum distance from its surface the electric potential is half of the electric potential at its centre?
Answer» Consider a sphere of radius R having charge q uniformly distributed inside it. At what minimum distance from its surface the electric potential is half of the electric potential at its centre?

Discussion

2.	Electric bulb 50W-100V glowing at full poi's used in parallel with battery 120V , 10ohm. Maximum number of bulbs that can be connected so that they glow in full power is ??
Answer» Electric bulb 50W-100V glowing at full poi's used in parallel with battery 120V , 10ohm. Maximum number of bulbs that can be connected so that they glow in full power is ??

Discussion

3.	A current of 1.0 A exists in a copper wire of cross - section 1.0 mm2. Assuming one free electron per atom calculate the drift speed of the free electrons in the wire. The density of copper is 9000 kgm−3.
Answer» A current of 1.0 A exists in a copper wire of cross - section 1.0 $m m^{2}$ . Assuming one free electron per atom calculate the drift speed of the free electrons in the wire. The density of copper is 9000 $k g m^{- 3}$ .

Discussion

4.	An up escalator is going at the rate of 10 step/min. How many steps per min should I move down on it as to look like that I am at rest to a person standing on ground.
Answer» An up escalator is going at the rate of 10 step/min. How many steps per min should I move down on it as to look like that I am at rest to a person standing on ground.

Discussion

5.	Two masses having masses M and m are moving in a circular path having radii R and r respectively. If their periods are same, then what is the ratio of their angular velocities?
Answer» Two masses having masses M and m are moving in a circular path having radii R and r respectively. If their periods are same, then what is the ratio of their angular velocities?

Discussion

6.	A string is in horizontal position as shown in figure, linear mass density of string is 415 kg m−1. Find the length (in m) of string if a standing wave is set on string with two loops formed. The frequency of the wave is 5 Hz. (Use g=10 m/s2)
Answer» A string is in horizontal position as shown in figure, linear mass density of string is $\frac{4}{15} {kg m}^{- 1}$ . Find the length $(in m)$ of string if a standing wave is set on string with two loops formed. The frequency of the wave is $5 Hz$ . (Use $g = 10 {m/s}^{2}$ )

Discussion

7.	The magnetic field due to a current carrying circular loop of radius 10 cm at a point on the axis, at a distance of 10 cm from the centre, is B. What will be its value at the centre of the loop?
Answer» The magnetic field due to a current carrying circular loop of radius $10 cm$ at a point on the axis, at a distance of $10 cm$ from the centre, is $B$ . What will be its value at the centre of the loop?

Discussion

8.	An unpolarized light of intensity I0 is passed through three polarizers. Polarizing angle between 1st and 3rd polarizer is 90∘ and that between 1st and 2nd polarizer is 30∘. If intensity of light after 3rd polarizer is xI08y then x+y is
Answer» An unpolarized light of intensity $I_{0}$ is passed through three polarizers. Polarizing angle between 1st and 3rd polarizer is $90^{\circ}$ and that between 1st and 2nd polarizer is $30^{\circ}$ . If intensity of light after 3rd polarizer is $\frac{x I_{0}}{8 y}$ then $x + y$ is

Discussion

9.	Which one of the graph represents the behaviour of an ideal gas at constant temperature?
Answer» Which one of the graph represents the behaviour of an ideal gas at constant temperature?

Discussion

10.	Twoconcentric circular coils X and Y of radii 16 cm and 10 cm,respectively, lie in the same vertical plane containing the north tosouth direction. Coil X has 20 turns and carries a current of 16 A;coil Y has 25 turns and carries a current of 18 A. The sense of thecurrent in X is anticlockwise, and clockwise in Y, for an observerlooking at the coils facing west. Give the magnitude and direction ofthe net magnetic field due to the coils at their centre.
Answer» Two concentric circular coils X and Y of radii 16 cm and 10 cm, respectively, lie in the same vertical plane containing the north to south direction. Coil X has 20 turns and carries a current of 16 A; coil Y has 25 turns and carries a current of 18 A. The sense of the current in X is anticlockwise, and clockwise in Y, for an observer looking at the coils facing west. Give the magnitude and direction of the net magnetic field due to the coils at their centre.

Discussion

11.	what is resis†an ce
Answer» what is resis†an ce

Discussion

12.	A train is moving on a circular curve of radius 1500m at the rate of 66 km/h. Through what angle has it turned in 10 seconds?
Answer» A train is moving on a circular curve of radius 1500m at the rate of 66 km/h. Through what angle has it turned in 10 seconds?

Discussion

13.	a posative charge q is placed in front of a conducting solid cube at a dis†an ce d from the center find the electric field at the center of cube due to charge appearing on it surface
Answer» a posative charge q is placed in front of a conducting solid cube at a dis†an ce d from the center find the electric field at the center of cube due to charge appearing on it surface

Discussion

14.	In the arrangement shown in the figure, slits S3 and S4 are having a variable separation Z. Point O on the screen is at the common perpendicular bisector of S1S2 and S3S4.When Z=λD2d the intensity measured at O is I0. The intensity at O when Z=2λDd is nI0. Find the value of n.
Answer» In the arrangement shown in the figure, slits $S_{3}$ and $S_{4}$ are having a variable separation $Z$ . Point $O$ on the screen is at the common perpendicular bisector of $S_{1} S_{2}$ and $S_{3} S_{4}$ . When $Z = \frac{λ D}{2 d}$ the intensity measured at $O$ is $I_{0}$ . The intensity at $O$ when $Z = \frac{2 λ D}{d}$ is $n I_{0}$ . Find the value of $n$ .

Discussion

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

Discussion

16.	How many significant figures are there in 0.310×105 m ?
Answer» How many significant figures are there in $0.310 \times 10^{5} m$ ?

Discussion

17.	Obtain the expression of relative velocity
Answer» Obtain the expression of relative velocity

Discussion

18.	Find the values of x for which A sin2x is minimum and Maximum. A is some positive constant.
Answer» Find the values of x for which A $s i n^{2} x$ is minimum and Maximum. A is some positive constant.

Discussion

19.	A sphere of brass released in a long liquid column attains a terminal speed v0. If the terminal speed attained by the sphere of marble of the same radius and released in the same liquid is nv0 , then the value of n will be.[ Given: The specific gravities of brass, marble and the liquid are 8.5,2.5 and 0.8 respectively.]
Answer» A sphere of brass released in a long liquid column attains a terminal speed $v_{0}$ . If the terminal speed attained by the sphere of marble of the same radius and released in the same liquid is $n v_{0}$ , then the value of n will be.[ Given: The specific gravities of brass, marble and the liquid are 8.5,2.5 and 0.8 respectively.]

Discussion

20.	Two masses M1 & M2 are initially at rest and are separated by a very large distance. If the masses approach each other subsequently due to gravitational attraction between them, their relative velocity of approach at a separation d is
Answer» Two masses $M_{1}$ & $M_{2}$ are initially at rest and are separated by a very large distance. If the masses approach each other subsequently due to gravitational attraction between them, their relative velocity of approach at a separation $d$ is

Discussion

21.	In the figure shown a cart moves on a smooth horizontal surface due to an external constant force of magnitude F. The initial mass of the cart is M0 and velocity is zero. Sand falls on to the cart with negligible velocity at constant rate μ kg/s and sticks to the cart. The velocity of the cart at time t is:
Answer» In the figure shown a cart moves on a smooth horizontal surface due to an external constant force of magnitude $F$ . The initial mass of the cart is $M_{0}$ and velocity is zero. Sand falls on to the cart with negligible velocity at constant rate $μ kg/s$ and sticks to the cart. The velocity of the cart at time $t$ is:

Discussion

22.	Angle of deviation of reflected ray of a plane mirror is denoted by what symbol??
Answer» Angle of deviation of reflected ray of a plane mirror is denoted by what symbol??

Discussion

23.	What is surface tension?
Answer» What is surface tension?

Discussion

24.	Three charges +4q , Q and q are placed in a straight line of length l at points 0 , l2 and l distance way from one end respectively. What should be Q in order to make the net force on q to be zero.
Answer» Three charges $+ 4 q, Q$ and $q$ are placed in a straight line of length $l$ at points $0, \frac{l}{2}$ and $l$ distance way from one end respectively. What should be $Q$ in order to make the net force on $q$ to be zero.

Discussion

25.	give the derivation of the formula for refraction in thick lense
Answer» give the derivation of the formula for refraction in thick lense

Discussion

26.	4. In the circuit all the bulbs consumes the same power if the resistance of bulb one is 36ohm then resistance of bulb 3 and 4 are
Answer» 4. In the circuit all the bulbs consumes the same power if the resistance of bulb one is 36ohm then resistance of bulb 3 and 4 are

Discussion

27.	24. Work done in increasing the current through a solenoid from zero to 2 ampere is 20 joule, work done in increasing the current from 4 to 6 A 1. 100 J 2. 60 J. 3. 80 J 4. 120J
Answer» 24. Work done in increasing the current through a solenoid from zero to 2 ampere is 20 joule, work done in increasing the current from 4 to 6 A 1. 100 J 2. 60 J. 3. 80 J 4. 120J

Discussion

28.	A sphere of mass m moving with a constant velocity u hits another stationary sphere of same mass. If e is the coefficient of restitution, then ratio of velocities of the two spheres v1v2 after collision will be
Answer» A sphere of mass m moving with a constant velocity $u$ hits another stationary sphere of same mass. If $e$ is the coefficient of restitution, then ratio of velocities of the two spheres $\frac{v_{1}}{v_{2}}$ after collision will be

Discussion

29.	The mass of an electron is 9.1×10−31kg.If its K.E.is 3.0×10−25J. Calculate its wavelength
Answer» The mass of an electron is $9.1 \times 10^{- 31} k g . I f i t s K . E . i s 3.0 \times 10^{- 25} J$ . Calculate its wavelength

Discussion

30.	A rectangular lamina is shown in the figure below. Find the radius of gyration about the axis passing through its COM, perpendicular to the plane of the rectangular lamina. [in metres]
Answer» A rectangular lamina is shown in the figure below. Find the radius of gyration about the axis passing through its COM, perpendicular to the plane of the rectangular lamina. [in $metres$ ]

Discussion

31.	What is sution coefficient
Answer» What is sution coefficient

Discussion

32.	How does the angle of minimum deviation of a glass prism vary, if the incident violet light is replaced by red light ? Give reason.
Answer» How does the angle of minimum deviation of a glass prism vary, if the incident violet light is replaced by red light ? Give reason.

Discussion

33.	estimate the distance for which ray optics is good approximation for anaperture of 4 mm and wavelength 400 nm?
Answer» estimate the distance for which ray optics is good approximation for anaperture of 4 mm and wavelength 400 nm?

Discussion

34.	The work done in slowly lifting a body from earth's surface to a height R (radius of earth) is equal to two times the work done in lifting the same body from earth's surface to a height h. Here h is equal to
Answer» The work done in slowly lifting a body from earth's surface to a height R (radius of earth) is equal to two times the work done in lifting the same body from earth's surface to a height h. Here h is equal to

Discussion

35.	A fan of weight Wf is suspended from the ceiling of a hall through a chain of weight Wc. How much force exerted by ceiling to the chain?
Answer» A fan of weight Wf is suspended from the ceiling of a hall through a chain of weight Wc. How much force exerted by ceiling to the chain?

Discussion

36.	There are two conducting spheres of radius aand b(b> a ) carrying equal and opposite charges.Theyare placed at a separation d (>\guillemotright\guillemotright a ancapacitance of system is
Answer» There are two conducting spheres of radius aand b(b> a ) carrying equal and opposite charges.Theyare placed at a separation d (>\guillemotright\guillemotright a ancapacitance of system is

Discussion

37.	a double slit experiment is performed woth light of wavelength 500 nm .A thin film of thickness 2 um anf refractive index 1.5 is introduced in thr path of upper beam .The central maximum wil
Answer» a double slit experiment is performed woth light of wavelength 500 nm .A thin film of thickness 2 um anf refractive index 1.5 is introduced in thr path of upper beam .The central maximum wil

Discussion

38.	An asteroid of mass M is approaching earth, initially at a distance of 10Re with speed Vi. It hits the earth with a speed Vf (Consider Re and Me as radius and mass of the earth), then:
Answer» An asteroid of mass M is approaching earth, initially at a distance of $10 R_{e}$ with speed $V_{i}$ . It hits the earth with a speed $V_{f}$ (Consider $R_{e}$ and $M_{e}$ as radius and mass of the earth), then:

Discussion

39.	A metal cylinder of length L is subjected to a uniform compressive force F as shown in the figure. The material of the cylinder has Young's modulus Y and Poisson’s ratio σ . The change in volume of the cylinder is
Answer» A metal cylinder of length L is subjected to a uniform compressive force F as shown in the figure. The material of the cylinder has Young's modulus Y and Poisson’s ratio $σ$ . The change in volume of the cylinder is

39.

A metal cylinder of length L is subjected to a uniform compressive force F as shown in the figure. The material of the cylinder has Young's modulus Y and Poisson’s ratio σ . The change in volume of the cylinder is

Answer»

A metal cylinder of length L is subjected to a uniform compressive force F as shown in the figure. The material of the cylinder has Young's modulus Y and Poisson’s ratio $σ$ . The change in volume of the cylinder is

Discussion

40.	A capacitor of capacitance 2 micro Faraday is connected in the tank ciruct of an oscillator oscillating with a frequency of 1KHz.if the current flowing in the circuit is 2 mA the voltage across the capacitor will be:
Answer» A capacitor of capacitance 2 micro Faraday is connected in the tank ciruct of an oscillator oscillating with a frequency of 1KHz.if the current flowing in the circuit is 2 mA the voltage across the capacitor will be:

Discussion

41.	A simple pendulum of length l and having a bob of mass M is suspended in a car. The car is moving on a circular track of radius R with a uniform speed v. If the pendulum makes small oscillations in a radial direction about its equilibrium position, what will be its time period ?
Answer» A simple pendulum of length l and having a bob of mass M is suspended in a car. The car is moving on a circular track of radius R with a uniform speed v. If the pendulum makes small oscillations in a radial direction about its equilibrium position, what will be its time period ?

Discussion

42.	The ratio of the numerical values of the average velocity and average speed of a body is always
Answer» The ratio of the numerical values of the average velocity and average speed of a body is always

Discussion

43.	The fundamental frequency of a string stretched with a block of mass 4 kg is 256 hz. The mass of block required to produce its octave is
Answer» The fundamental frequency of a string stretched with a block of mass 4 kg is 256 hz. The mass of block required to produce its octave is

Discussion

44.	A meter stick is pivoted about its centre. A piece of wax of mass 20 g travelling horizontally and perpendicular to it at 5 m/s strikes and adheres to one end of the stick which starts to rotate in a horizontal circle. Given, the moment of inertia of the stick and wax about the pivot is 0.02 kg m2, the angular velocity of the stick is
Answer» A meter stick is pivoted about its centre. A piece of wax of mass $20 g$ travelling horizontally and perpendicular to it at $5 m/s$ strikes and adheres to one end of the stick which starts to rotate in a horizontal circle. Given, the moment of inertia of the stick and wax about the pivot is $0.02 {kg m}^{2}$ , the angular velocity of the stick is

Discussion

45.	If r is the distance of a point from the centre of a short dipole then the electric field due to the short dipole remains proportional to?
Answer» If r is the distance of a point from the centre of a short dipole then the electric field due to the short dipole remains proportional to?

Discussion

46.	A plane wavefront hits convex lens as shown in figure. Which graph represent refracted wavefront from lens.
Answer» A plane wavefront hits convex lens as shown in figure. Which graph represent refracted wavefront from lens.

Discussion

47.	Velocity of sound in O2 gas at 0 degree is 320m/s. What will be the velocity of sound in mixture of two parts by volume of hydrogen and one part by volume of oxygen at the same temperature?
Answer» Velocity of sound in O₂gas at 0 degree is 320m/s. What will be the velocity of sound in mixture of two parts by volume of hydrogen and one part by volume of oxygen at the same temperature?

Discussion

48.	7.Let siny=xsin (a+y) then dy/dx equals
Answer» 7.Let siny=xsin (a+y) then dy/dx equals

Discussion

49.	half padt of a wire of resis†an e R is stretched to make it longer 1% and remaining half isstretched to make it 2%longer.The new resis†an ce if the wire is nearl
Answer» half padt of a wire of resis†an e R is stretched to make it longer 1% and remaining half isstretched to make it 2%longer.The new resis†an ce if the wire is nearl

Discussion

50.	In an accelerator experiment on high-energy collisions of electronswith positrons, a certain event is interpreted as annihilation of anelectron-positron pair of total energy 10.2 BeV into two γ-rays ofequal energy. What is the wavelength associated with each γ-ray?(1BeV = 109eV)
Answer» In an accelerator experiment on high-energy collisions of electronswith positrons, a certain event is interpreted as annihilation of anelectron-positron pair of total energy 10.2 BeV into two γ-rays ofequal energy. What is the wavelength associated with each γ-ray?(1BeV = 109eV)

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Consider a sphere of radius R having charge q uniformly distributed inside it. At what minimum distance from its surface the electric potential is half of the electric potential at its centre?

Electric bulb 50W-100V glowing at full poi's used in parallel with battery 120V , 10ohm. Maximum number of bulbs that can be connected so that they glow in full power is ??

A current of 1.0 A exists in a copper wire of cross - section 1.0 mm2. Assuming one free electron per atom calculate the drift speed of the free electrons in the wire. The density of copper is 9000 kgm−3.

An up escalator is going at the rate of 10 step/min. How many steps per min should I move down on it as to look like that I am at rest to a person standing on ground.

Two masses having masses M and m are moving in a circular path having radii R and r respectively. If their periods are same, then what is the ratio of their angular velocities?

A string is in horizontal position as shown in figure, linear mass density of string is 415 kg m−1. Find the length (in m) of string if a standing wave is set on string with two loops formed. The frequency of the wave is 5 Hz. (Use g=10 m/s2)

The magnetic field due to a current carrying circular loop of radius 10 cm at a point on the axis, at a distance of 10 cm from the centre, is B. What will be its value at the centre of the loop?

An unpolarized light of intensity I0 is passed through three polarizers. Polarizing angle between 1st and 3rd polarizer is 90∘ and that between 1st and 2nd polarizer is 30∘. If intensity of light after 3rd polarizer is xI08y then x+y is

Which one of the graph represents the behaviour of an ideal gas at constant temperature?

what is resis†an ce

A train is moving on a circular curve of radius 1500m at the rate of 66 km/h. Through what angle has it turned in 10 seconds?

a posative charge q is placed in front of a conducting solid cube at a dis†an ce d from the center find the electric field at the center of cube due to charge appearing on it surface

In the arrangement shown in the figure, slits S3 and S4 are having a variable separation Z. Point O on the screen is at the common perpendicular bisector of S1S2 and S3S4.When Z=λD2d the intensity measured at O is I0. The intensity at O when Z=2λDd is nI0. Find the value of n.

The magnitude of the rotational analog of linear momentum is .

How many significant figures are there in 0.310×105 m ?

Obtain the expression of relative velocity

Find the values of x for which A sin2x is minimum and Maximum. A is some positive constant.

Two masses M1 &amp; M2 are initially at rest and are separated by a very large distance. If the masses approach each other subsequently due to gravitational attraction between them, their relative velocity of approach at a separation d is

Angle of deviation of reflected ray of a plane mirror is denoted by what symbol??

What is surface tension?

Three charges +4q , Q and q are placed in a straight line of length l at points 0 , l2 and l distance way from one end respectively. What should be Q in order to make the net force on q to be zero.

give the derivation of the formula for refraction in thick lense

4. In the circuit all the bulbs consumes the same power if the resistance of bulb one is 36ohm then resistance of bulb 3 and 4 are

24. Work done in increasing the current through a solenoid from zero to 2 ampere is 20 joule, work done in increasing the current from 4 to 6 A 1. 100 J 2. 60 J. 3. 80 J 4. 120J

A sphere of mass m moving with a constant velocity u hits another stationary sphere of same mass. If e is the coefficient of restitution, then ratio of velocities of the two spheres v1v2 after collision will be

The mass of an electron is 9.1×10−31kg.If its K.E.is 3.0×10−25J. Calculate its wavelength

A rectangular lamina is shown in the figure below. Find the radius of gyration about the axis passing through its COM, perpendicular to the plane of the rectangular lamina. [in metres]

What is sution coefficient

How does the angle of minimum deviation of a glass prism vary, if the incident violet light is replaced by red light ? Give reason.

estimate the distance for which ray optics is good approximation for anaperture of 4 mm and wavelength 400 nm?

The work done in slowly lifting a body from earth's surface to a height R (radius of earth) is equal to two times the work done in lifting the same body from earth's surface to a height h. Here h is equal to

A fan of weight Wf is suspended from the ceiling of a hall through a chain of weight Wc. How much force exerted by ceiling to the chain?

There are two conducting spheres of radius aand b(b> a ) carrying equal and opposite charges.Theyare placed at a separation d (>\guillemotright\guillemotright a ancapacitance of system is

a double slit experiment is performed woth light of wavelength 500 nm .A thin film of thickness 2 um anf refractive index 1.5 is introduced in thr path of upper beam .The central maximum wil

An asteroid of mass M is approaching earth, initially at a distance of 10Re with speed Vi. It hits the earth with a speed Vf (Consider Re and Me as radius and mass of the earth), then:

A metal cylinder of length L is subjected to a uniform compressive force F as shown in the figure. The material of the cylinder has Young's modulus Y and Poisson’s ratio σ . The change in volume of the cylinder is

A capacitor of capacitance 2 micro Faraday is connected in the tank ciruct of an oscillator oscillating with a frequency of 1KHz.if the current flowing in the circuit is 2 mA the voltage across the capacitor will be:

A simple pendulum of length l and having a bob of mass M is suspended in a car. The car is moving on a circular track of radius R with a uniform speed v. If the pendulum makes small oscillations in a radial direction about its equilibrium position, what will be its time period ?

The ratio of the numerical values of the average velocity and average speed of a body is always

The fundamental frequency of a string stretched with a block of mass 4 kg is 256 hz. The mass of block required to produce its octave is

If r is the distance of a point from the centre of a short dipole then the electric field due to the short dipole remains proportional to?

A plane wavefront hits convex lens as shown in figure. Which graph represent refracted wavefront from lens.

Velocity of sound in O​​​​​​2 ​​​​​​gas at 0 degree is 320m/s. What will be the velocity of sound in mixture of two parts by volume of hydrogen and one part by volume of oxygen at the same temperature?

7.Let siny=xsin (a+y) then dy/dx equals

half padt of a wire of resis†an e R is stretched to make it longer 1% and remaining half isstretched to make it 2%longer.The new resis†an ce if the wire is nearl

In an accelerator experiment on high-energy collisions of electronswith positrons, a certain event is interpreted as annihilation of anelectron-positron pair of total energy 10.2 BeV into two γ-rays ofequal energy. What is the wavelength associated with each γ-ray?(1BeV = 109eV)

Two masses M1 & M2 are initially at rest and are separated by a very large distance. If the masses approach each other subsequently due to gravitational attraction between them, their relative velocity of approach at a separation d is

Velocity of sound in O2 gas at 0 degree is 320m/s. What will be the velocity of sound in mixture of two parts by volume of hydrogen and one part by volume of oxygen at the same temperature?