50278 + Interview Questions in Physics

1.	4. In Millikan's oil drop experiment, a charged drop of mass1.8 10-14 kg is stationary between the plates. Thedistance between the plates is 0.9 cm and potentialdifference between the plates is 2000 volt. The number ofelectrons on the oil drop is(1) 10(3) 50(2) 5(4) 20
Answer» 4. In Millikan's oil drop experiment, a charged drop of mass1.8 10-14 kg is stationary between the plates. Thedistance between the plates is 0.9 cm and potentialdifference between the plates is 2000 volt. The number ofelectrons on the oil drop is(1) 10(3) 50(2) 5(4) 20

Discussion

2.	Condition of superimposition of1) standing wave2)progress wave
Answer» Condition of superimposition of 1) standing wave 2)progress wave

Discussion

3.	How the change in velocity comes to be 2vsin●/2, when velocity makes an angle difference of 90°.
Answer» How the change in velocity comes to be 2vsin●/2, when velocity makes an angle difference of 90°.

Discussion

4.	A projectile is thrown at an angle θ with the horizontal and its range is R1, and time of flight is T1. Itis then thrown at an angle θ with vertical and the range is R2 and time of flight T2. Then3.
Answer» A projectile is thrown at an angle θ with the horizontal and its range is R1, and time of flight is T1. Itis then thrown at an angle θ with vertical and the range is R2 and time of flight T2. Then3.

Discussion

5.	A body moves in such a way that displacement is 12 m east 5 m north nd 9 m vertically upward. Find magnitude of displacement
Answer» A body moves in such a way that displacement is 12 m east 5 m north nd 9 m vertically upward. Find magnitude of displacement

Discussion

6.	The magnification produced by an astronomical telescope for normal adjustment is 10 and the length of the telescope is 1.1 m. The magnification when the image is formed at least distance of distinct vision is -[Use, D=25 cm]
Answer» The magnification produced by an astronomical telescope for normal adjustment is $10$ and the length of the telescope is $1.1 m .$ The magnification when the image is formed at least distance of distinct vision is - [Use, $D = 25 cm$ ]

Discussion

7.	Two identical solenoid coils, each of self inductance L are connected in series. Their, turns are in the same sense and the distance between them is such that the coefficient of coupling is half. Then, the equivalent inductance of the combination is
Answer» Two identical solenoid coils, each of self inductance $L$ are connected in series. Their, turns are in the same sense and the distance between them is such that the coefficient of coupling is half. Then, the equivalent inductance of the combination is

Discussion

8.	blue color of sky is due to 1.reflection 2.refraction 3.scattering 4.dispersion
Answer» blue color of sky is due to 1.reflection 2.refraction 3.scattering 4.dispersion

Discussion

9.	Answer the following questions: (a) Quarks inside protons and neutrons are thought to carryfractional charges [(+2/3)e ; (–1/3)e]. Why do they not show upin Millikan’s oil-drop experiment? (b) What is so special about the combination e/m? Why do we notsimply talk of e and m separately? (c) Why should gases be insulators at ordinary pressures and startconducting at very low pressures? (d) Every metal has a definite work function. Why do allphotoelectrons not come out with the same energy if incidentradiation is monochromatic? Why is there an energy distributionof photoelectrons? (e) The energy and momentum of an electron are related to thefrequency and wavelength of the associated matter wave by therelations:E = h ν, p = λhBut while the value of λ is physically significant, the value of ν(and therefore, the value of the phase speed ν λ) has no physicalsignificance. Why?
Answer» Answer the following questions: (a) Quarks inside protons and neutrons are thought to carryfractional charges [(+2/3)e ; (–1/3)e]. Why do they not show upin Millikan’s oil-drop experiment? (b) What is so special about the combination e/m? Why do we notsimply talk of e and m separately? (c) Why should gases be insulators at ordinary pressures and startconducting at very low pressures? (d) Every metal has a definite work function. Why do allphotoelectrons not come out with the same energy if incidentradiation is monochromatic? Why is there an energy distributionof photoelectrons? (e) The energy and momentum of an electron are related to thefrequency and wavelength of the associated matter wave by therelations:E = h ν, p = λhBut while the value of λ is physically significant, the value of ν(and therefore, the value of the phase speed ν λ) has no physicalsignificance. Why?

Discussion

10.	Rain driven by the wind, falls on a railway compartment with a velocity of 20 m/s, at an angle of 30∘ to the vertical. The train moves, along the direction of wind flow, at a speed of 108 km/hr. Determine the apparent velocity ( in m/s upto two decimal places) of rain as observed by a person sitting in the train.( Given √7=2.64)
Answer» Rain driven by the wind, falls on a railway compartment with a velocity of $20 m/s$ , at an angle of $30^{\circ}$ to the vertical. The train moves, along the direction of wind flow, at a speed of $108 km/hr$ . Determine the apparent velocity ( in $m/s$ upto two decimal places) of rain as observed by a person sitting in the train.( Given $\sqrt{7} = 2.64$ )

Discussion

11.	A uniform chain of length L and mass M is lying on a smooth table and one third of its length is hanging vertically down over the edge of the table. If g is acceleration due to gravity, the work required to pull the hanging part on the table is
Answer» A uniform chain of length $L$ and mass $M$ is lying on a smooth table and one third of its length is hanging vertically down over the edge of the table. If $g$ is acceleration due to gravity, the work required to pull the hanging part on the table is

Discussion

12.	Calculate the work done, if a wire is loaded by 'Mg' weight and the increase in length is 'l'
Answer» Calculate the work done, if a wire is loaded by 'Mg' weight and the increase in length is 'l'

Discussion

13.	Q) If T is the time of flight, H is the maximum height, then y-co-ordinate of the projectile at any time t is (for ground to ground projectile)
Answer» Q) If T is the time of flight, H is the maximum height, then y-co-ordinate of the projectile at any time t is (for ground to ground projectile)

Discussion

14.	Ball A having initial velocity u=5 m/s collides elastically with block B initially at rest as shown in the figure. If both balls have the same mass, and the height of the tower is h=20 m, find the horizontal distance d traveled by ball B before hitting the ground.
Answer» Ball $A$ having initial velocity $u = 5 m/s$ collides elastically with block $B$ initially at rest as shown in the figure. If both balls have the same mass, and the height of the tower is $h = 20 m$ , find the horizontal distance $d$ traveled by ball $B$ before hitting the ground.

Discussion

15.	A person of mass M IS , sitting on a swing of length L and swinging with an angular amplitude Θ0 . If the person stands up when the swing passes through its lowest point , the work done by him is close to : (assuming that his center of mass moves by a distance l(l<<L)) ,
Answer» A person of mass $M$ IS , sitting on a swing of length $L$ and swinging with an angular amplitude $Θ_{0}$ . If the person stands up when the swing passes through its lowest point , the work done by him is close to : (assuming that his center of mass moves by a distance $l (l << L)$ ) ,

Discussion

16.	During an experiment of formation of image using concave mirror Position of mirror =10 cm Position of candle =50 cm Position of screen =90 cm Find the focal length of mirror and draw the ray diagram using these distance by assuming suitable scale .
Answer» During an experiment of formation of image using concave mirror Position of mirror =10 cm Position of candle =50 cm Position of screen =90 cm Find the focal length of mirror and draw the ray diagram using these distance by assuming suitable scale .

Discussion

17.	A potentiometer wire has length 4m and resis†an ce 8 ohm the resis†an ce that must be connected in series with the wire and an accumulator oh emf 2v so as to get a potential gradient 1mV per cm on the wire i
Answer» A potentiometer wire has length 4m and resis†an ce 8 ohm the resis†an ce that must be connected in series with the wire and an accumulator oh emf 2v so as to get a potential gradient 1mV per cm on the wire i

Discussion

18.	A partical is moving with uniform acceleration along a straight line A,B,C its velocity at A is 6m/s and at B is 9m/sif the ratio AB:BC IS 5:3 THEN find its velocity at C ?
Answer» A partical is moving with uniform acceleration along a straight line A,B,C its velocity at A is 6m/s and at B is 9m/sif the ratio AB:BC IS 5:3 THEN find its velocity at C ?

Discussion

19.	In the figure shown below,
Answer» In the figure shown below,

Discussion

20.	For an electromagnetic wave travelling in free space, the relation between average energy densities due to electric (Ue) and magnetic (Um) fields is:
Answer» For an electromagnetic wave travelling in free space, the relation between average energy densities due to electric $(U_{e})$ and magnetic $(U_{m})$ fields is:

Discussion

21.	Four point masses, each of value m are placed at the corners of square ABCD of side l. The moment of inertia of this system about an axis passing through A and parallel to BD is
Answer» Four point masses, each of value $m$ are placed at the corners of square $A B C D$ of side $l$ . The moment of inertia of this system about an axis passing through $A$ and parallel to $B D$ is

Discussion

22.	Two similar conductor spheres having charges +q and –q are placed at a separation 'd' from each other in air. The radius of each sphere is r and the separation between their centres is d (d >> r). Calculate the capacitance of the system
Answer» Two similar conductor spheres having charges +q and –q are placed at a separation 'd' from each other in air. The radius of each sphere is r and the separation between their centres is d (d >> r). Calculate the capacitance of the system

22.

Two similar conductor spheres having charges +q and –q are placed at a separation 'd' from each other in air. The radius of each sphere is r and the separation between their centres is d (d >> r). Calculate the capacitance of the system

Answer»

Two similar conductor spheres having charges +q and –q are placed at a separation 'd' from each other in air. The radius of each sphere is r and the separation between their centres is d (d >> r). Calculate the capacitance of the system

Discussion

23.	If the error in measurement of momentum of a particle is 10% and mass is known exactly, the permissible error in the determination of kinetic energy is ___
Answer» If the error in measurement of momentum of a particle is 10% and mass is known exactly, the permissible error in the determination of kinetic energy is ___

Discussion

24.	A force acts for 10 sec on a body of mass 100 kg which was at rest, after which it ceases to act. If the body travels 160 m in the next 8 sec, find the magnitude of the force.
Answer» A force acts for $10 sec$ on a body of mass $100 kg$ which was at rest, after which it ceases to act. If the body travels $160 m$ in the next $8 sec$ , find the magnitude of the force.

Discussion

25.	what is optical density ?what is reflective index ?
Answer» what is optical density ? what is reflective index ?

Discussion

26.	The loudness of sound depends upon _______.
Answer» The loudness of sound depends upon _______.

Discussion

27.	Why electrostatic force constant 'k' depends on medium?
Answer» Why electrostatic force constant 'k' depends on medium?

Discussion

28.	For the circuit shown in the figure, find the current passing through 10 Ω resistor.
Answer» For the circuit shown in the figure, find the current passing through $10 Ω$ resistor.

Discussion

29.	A plank with a mass M= 6.00 kg rests on top of two identical solid cylindrical rollers that have R=5.00 cm and m=2.00 kg (figure). The plank is pulled by a constant horizontal force →F of magnitude 6.00 N applied to the end of the plank and perpendicular to the axes of the cylinders(which are parallel). The cylinders roll without slipping on a flat surface. There is also no slipping between the cylinders and the plank. All surfaces are rough. The initial acceleration of the plank at the moment when the rollers are equidistant from the ends of the plank is m/s2.
Answer» A plank with a mass $M = 6.00 k g$ rests on top of two identical solid cylindrical rollers that have $R = 5.00 c m$ and $m = 2.00 k g$ (figure). The plank is pulled by a constant horizontal force $\to F$ of magnitude $6.00$ $N$ applied to the end of the plank and perpendicular to the axes of the cylinders(which are parallel). The cylinders roll without slipping on a flat surface. There is also no slipping between the cylinders and the plank. All surfaces are rough. The initial acceleration of the plank at the moment when the rollers are equidistant from the ends of the plank is $m / s^{2}$ .

Discussion

30.	The Fresnel distance for aperture of 1 mm using red light of wavelength 7000 ˚A is -
Answer» The Fresnel distance for aperture of $1 mm$ using red light of wavelength $7000 ˚ A$ is -

Discussion

31.	The electric field in a region is given by →E=45E0^i+35E0^j where E0=3.0×103 NC−1. The flyux of this field through a square surface of area 0.4 m2 parallel to the z−x palne (in S.I units) is
Answer» The electric field in a region is given by $\to E = \frac{4}{5} E_{0}^i + \frac{3}{5} E_{0}^j w h e r e E_{0} = 3.0 \times 10^{3} N C^{- 1}$ . The flyux of this field through a square surface of area $0.4 m^{2}$ parallel to the $z - x$ palne (in $S . I$ units) is

Discussion

32.	while calculating electric flux on 3D BODY we are concerned with only projected area and not with surface area
Answer» while calculating electric flux on 3D BODY we are concerned with only projected area and not with surface area

Discussion

33.	The time period of a charge particle which is projected in a magnetic field B with velocity at an angle with the directionof magnetic field is
Answer» The time period of a charge particle which is projected in a magnetic field B with velocity at an angle with the directionof magnetic field is

Discussion

34.	When a uranium 23592U isotope in bombarded with a neutron, it generates 8936Kr, three neutrons and :
Answer» When a uranium $23592 U$ isotope in bombarded with a neutron, it generates $8936 Kr$ , three neutrons and :

Discussion

35.	If position x=t^3 - 2t + 5(m) then velocity at time t = 2 s is
Answer» If position x=t^3 - 2t + 5(m) then velocity at time t = 2 s is

Discussion

36.	10. A block of mass 1 kg and charge q is tied to a springof spring constant k. The electric field intensity E isswitched ON. The maximum displacement in thespring will beole2k2qE
Answer» 10. A block of mass 1 kg and charge q is tied to a springof spring constant k. The electric field intensity E isswitched ON. The maximum displacement in thespring will beole2k2qE

Discussion

37.	A body of mass m is placed on the earth's surface. It is taken from the earth's surface to a height h=3R. The change in gravitational energy of the body is
Answer» A body of mass m is placed on the earth's surface. It is taken from the earth's surface to a height h=3R. The change in gravitational energy of the body is

Discussion

38.	Two similar open organ pipes of length 50 cm and 50.5 cm produce 3 beats per second when sounded together in fundamental nodes. The velocity of sound in air is
Answer» Two similar open organ pipes of length $50 cm$ and $50.5 cm$ produce $3 beats per second$ when sounded together in fundamental nodes. The velocity of sound in air is

Discussion

39.	is oxide ion paramagnetic or diamagnetic
Answer» is oxide ion paramagnetic or diamagnetic

Discussion

40.	A bus travelling the first one-third distance at a speed of 10 km/h, the next one-third at 20 km/h and the last one-third at 60 km/h. The average speed of the bus is
Answer» A bus travelling the first one-third distance at a speed of $10 km/h,$ the next one-third at $20 km/h$ and the last one-third at $60 km/h$ . The average speed of the bus is

Discussion

41.	5.A ball is allowed to fall from top of a building. If t, istime taken to fall first one fourth th of its height and t, is timetaken to fall last one fourth th of its height then,
Answer» 5.A ball is allowed to fall from top of a building. If t, istime taken to fall first one fourth th of its height and t, is timetaken to fall last one fourth th of its height then,

Discussion

42.	13. A binary star consists of two stars(mass 2.2M) and B(11M) where M is the mass of the sun. They are seperated by a distance d and are rotating about their centre of mass which is stationary. The ratio of total angular momentum of binary star to the angular momentum of star B about the centre of mass is
Answer» 13. A binary star consists of two stars(mass 2.2M) and B(11M) where M is the mass of the sun. They are seperated by a distance d and are rotating about their centre of mass which is stationary. The ratio of total angular momentum of binary star to the angular momentum of star B about the centre of mass is

Discussion

43.	What should be the angle between two plane mirrors so that whatever be the angle of incidence, the incident ray and the reflected ray from the two mirrors be parallel to each other
Answer» What should be the angle between two plane mirrors so that whatever be the angle of incidence, the incident ray and the reflected ray from the two mirrors be parallel to each other

Discussion

44.	29. How to remember trigonometric table
Answer» 29. How to remember trigonometric table

Discussion

45.	For VHF signal broadcasting, _____ km2 of maximum service area will be covered by an antenna tower of height 30 m, if the receiving antenna is placed on the ground.(Let radius of the earth be 6400 km)(Round off to the nearest integer)(Take π as 3.14)
Answer» For $VHF$ signal broadcasting, _____ ${km}^{2}$ of maximum service area will be covered by an antenna tower of height $30 m$ , if the receiving antenna is placed on the ground. $($ Let radius of the earth be $6400 km)$ $($ Round off to the nearest integer $)$ $($ Take $π$ as $3.14)$

Discussion

46.	The work done in moving a body of mass 4kg with uniform velocity of 5ms−1 for 10 seconds on a surface of μ=0.4(takeg=10 m/s2)
Answer» The work done in moving a body of mass 4kg with uniform velocity of $5 m s^{- 1}$ for 10 seconds on a surface of $μ = 0.4 (t a k e g = 10 m / s^{2})$

Discussion

47.	41. Assertion :- M.P order XeF6>XeF4>XeF2 Reason :- Vander wall's Force always increase with increase in the moleculer weight. 1. A 2. B 3. C 4. D
Answer» 41. Assertion :- M.P order XeF6>XeF4>XeF2 Reason :- Vander wall's Force always increase with increase in the moleculer weight. 1. A 2. B 3. C 4. D

Discussion

48.	A particle is dropped from a height h on a floor, if the coefficient of restitution is e. Find the time taken by ball before second bounce.
Answer» A particle is dropped from a height $h$ on a floor, if the coefficient of restitution is $e$ . Find the time taken by ball before second bounce.

Discussion

49.	Difference between motion and rest.
Answer» Difference between motion and rest.

Discussion

50.	143.A particle is moving along a circle of radius 20 cm with a linear velocity of 2m per second calculate angular velocity of particle
Answer» 143.A particle is moving along a circle of radius 20 cm with a linear velocity of 2m per second calculate angular velocity of particle

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

4. In Millikan's oil drop experiment, a charged drop of mass1.8 10-14 kg is stationary between the plates. Thedistance between the plates is 0.9 cm and potentialdifference between the plates is 2000 volt. The number ofelectrons on the oil drop is(1) 10(3) 50(2) 5(4) 20

Condition of superimposition of1) standing wave2)progress wave

How the change in velocity comes to be 2vsin●/2, when velocity makes an angle difference of 90°.

A projectile is thrown at an angle θ with the horizontal and its range is R1, and time of flight is T1. Itis then thrown at an angle θ with vertical and the range is R2 and time of flight T2. Then3.

A body moves in such a way that displacement is 12 m east 5 m north nd 9 m vertically upward. Find magnitude of displacement

The magnification produced by an astronomical telescope for normal adjustment is 10 and the length of the telescope is 1.1 m. The magnification when the image is formed at least distance of distinct vision is -[Use, D=25 cm]

Two identical solenoid coils, each of self inductance L are connected in series. Their, turns are in the same sense and the distance between them is such that the coefficient of coupling is half. Then, the equivalent inductance of the combination is

blue color of sky is due to 1.reflection 2.refraction 3.scattering 4.dispersion

A uniform chain of length L and mass M is lying on a smooth table and one third of its length is hanging vertically down over the edge of the table. If g is acceleration due to gravity, the work required to pull the hanging part on the table is

Calculate the work done, if a wire is loaded by 'Mg' weight and the increase in length is 'l'

Q) If T is the time of flight, H is the maximum height, then y-co-ordinate of the projectile at any time t is (for ground to ground projectile)

Ball A having initial velocity u=5 m/s collides elastically with block B initially at rest as shown in the figure. If both balls have the same mass, and the height of the tower is h=20 m, find the horizontal distance d traveled by ball B before hitting the ground.

A person of mass M IS , sitting on a swing of length L and swinging with an angular amplitude Θ0 . If the person stands up when the swing passes through its lowest point , the work done by him is close to : (assuming that his center of mass moves by a distance l(l&lt;&lt;L)) ,

During an experiment of formation of image using concave mirror Position of mirror =10 cm Position of candle =50 cm Position of screen =90 cm Find the focal length of mirror and draw the ray diagram using these distance by assuming suitable scale .

A potentiometer wire has length 4m and resis†an ce 8 ohm the resis†an ce that must be connected in series with the wire and an accumulator oh emf 2v so as to get a potential gradient 1mV per cm on the wire i

A partical is moving with uniform acceleration along a straight line A,B,C its velocity at A is 6m/s and at B is 9m/sif the ratio AB:BC IS 5:3 THEN find its velocity at C ?

In the figure shown below,

For an electromagnetic wave travelling in free space, the relation between average energy densities due to electric (Ue) and magnetic (Um) fields is:

Four point masses, each of value m are placed at the corners of square ABCD of side l. The moment of inertia of this system about an axis passing through A and parallel to BD is

Two similar conductor spheres having charges +q and –q are placed at a separation 'd' from each other in air. The radius of each sphere is r and the separation between their centres is d (d &gt;&gt; r). Calculate the capacitance of the system

If the error in measurement of momentum of a particle is 10% and mass is known exactly, the permissible error in the determination of kinetic energy is ___

A force acts for 10 sec on a body of mass 100 kg which was at rest, after which it ceases to act. If the body travels 160 m in the next 8 sec, find the magnitude of the force.

what is optical density ?what is reflective index ?

The loudness of sound depends upon _______.

Why electrostatic force constant 'k' depends on medium? ​​​​​​

For the circuit shown in the figure, find the current passing through 10 Ω resistor.

The Fresnel distance for aperture of 1 mm using red light of wavelength 7000 ˚A is -

The electric field in a region is given by →E=45E0^i+35E0^j where E0=3.0×103 NC−1. The flyux of this field through a square surface of area 0.4 m2 parallel to the z−x palne (in S.I units) is

while calculating electric flux on 3D BODY we are concerned with only projected area and not with surface area

The time period of a charge particle which is projected in a magnetic field B with velocity at an angle with the directionof magnetic field is

When a uranium 23592U isotope in bombarded with a neutron, it generates 8936Kr, three neutrons and :

If position x=t^3 - 2t + 5(m) then velocity at time t = 2 s is

10. A block of mass 1 kg and charge q is tied to a springof spring constant k. The electric field intensity E isswitched ON. The maximum displacement in thespring will beole2k2qE

A body of mass m is placed on the earth's surface. It is taken from the earth's surface to a height h=3R. The change in gravitational energy of the body is

Two similar open organ pipes of length 50 cm and 50.5 cm produce 3 beats per second when sounded together in fundamental nodes. The velocity of sound in air is

is oxide ion paramagnetic or diamagnetic

A bus travelling the first one-third distance at a speed of 10 km/h, the next one-third at 20 km/h and the last one-third at 60 km/h. The average speed of the bus is

5.A ball is allowed to fall from top of a building. If t, istime taken to fall first one fourth th of its height and t, is timetaken to fall last one fourth th of its height then,

What should be the angle between two plane mirrors so that whatever be the angle of incidence, the incident ray and the reflected ray from the two mirrors be parallel to each other

29. How to remember trigonometric table

For VHF signal broadcasting, _____ km2 of maximum service area will be covered by an antenna tower of height 30 m, if the receiving antenna is placed on the ground.(Let radius of the earth be 6400 km)(Round off to the nearest integer)(Take π as 3.14)

The work done in moving a body of mass 4kg with uniform velocity of 5ms−1 for 10 seconds on a surface of μ=0.4(takeg=10 m/s2)

41. Assertion :- M.P order XeF6>XeF4>XeF2 Reason :- Vander wall's Force always increase with increase in the moleculer weight. 1. A 2. B 3. C 4. D

A particle is dropped from a height h on a floor, if the coefficient of restitution is e. Find the time taken by ball before second bounce.

Difference between motion and rest.

143.A particle is moving along a circle of radius 20 cm with a linear velocity of 2m per second calculate angular velocity of particle

A person of mass M IS , sitting on a swing of length L and swinging with an angular amplitude Θ0 . If the person stands up when the swing passes through its lowest point , the work done by him is close to : (assuming that his center of mass moves by a distance l(l<<L)) ,

Two similar conductor spheres having charges +q and –q are placed at a separation 'd' from each other in air. The radius of each sphere is r and the separation between their centres is d (d >> r). Calculate the capacitance of the system

Why electrostatic force constant 'k' depends on medium?