50278 + Interview Questions in Physics

1.	Two uniform rods AB and BC of masses 1 kg and 2 kg respectively having lengths 2 m and 1 m respectively are joined to each other at B. They can rotate freely about B without any friction. The assembly is kept on a smooth horizontal surface as shown in figure. A horizontal impulse P = 10 Ns is applied on the rod AB at a distance 0.5 m from point B perpendicular to the rod Angular momentum of rod BC about centre of rod BC just after application of impulse is
Answer» Two uniform rods AB and BC of masses 1 kg and 2 kg respectively having lengths 2 m and 1 m respectively are joined to each other at B. They can rotate freely about B without any friction. The assembly is kept on a smooth horizontal surface as shown in figure. A horizontal impulse P = 10 Ns is applied on the rod AB at a distance 0.5 m from point B perpendicular to the rod Angular momentum of rod BC about centre of rod BC just after application of impulse is

1.

Two uniform rods AB and BC of masses 1 kg and 2 kg respectively having lengths 2 m and 1 m respectively are joined to each other at B. They can rotate freely about B without any friction. The assembly is kept on a smooth horizontal surface as shown in figure. A horizontal impulse P = 10 Ns is applied on the rod AB at a distance 0.5 m from point B perpendicular to the rod Angular momentum of rod BC about centre of rod BC just after application of impulse is

Answer»

Two uniform rods AB and BC of masses 1 kg and 2 kg respectively having lengths 2 m and 1 m respectively are joined to each other at B. They can rotate freely about B without any friction. The assembly is kept on a smooth horizontal surface as shown in figure.
A horizontal impulse P = 10 Ns is applied on the rod
AB at a distance 0.5 m from point B perpendicular to the rod

Angular momentum of rod BC about centre of rod BC just after application of impulse is

2.	Figure shows a quarter circle. A particle moves from B to O with 5 m/s, from O to A with 7 m/s. With what speed the particle should move from A to B so that average speed for total journey is 6 m/s?
Answer» Figure shows a quarter circle. A particle moves from $B$ to $O$ with $5 m / s$ , from $O$ to $A$ with $7 m / s$ . With what speed the particle should move from $A$ to $B$ so that average speed for total journey is $6 m / s$ ?

3.	For the cell: Tl(s)\|Tl+(0.001M)\|\|Cu2+(0.1M)\|Cu(s): Ecell = 0.83 V at 298 K, The cell potential can be increased by
Answer» For the cell: $T l_{(s)} \| T l^{+} (0.001 M) \| \| C u^{2 +} (0.1 M) \| C u_{(s)} :$ $E_{c e l l}$ = 0.83 V at 298 K, The cell potential can be increased by

4.	Two plates 1 and 2 move with velocities −v and 2v respectively. If the sphere does not slide relative to the plates, assuming the masses of each body as m, find the kinetic energy of the system (plate+sphere).
Answer» Two plates 1 and 2 move with velocities $- v$ and $2 v$ respectively. If the sphere does not slide relative to the plates, assuming the masses of each body as $m$ , find the kinetic energy of the system (plate+sphere).

6.	Range of frequencies allotted for commercial FM radio broadcast is
Answer» Range of frequencies allotted for commercial FM radio broadcast is

8.	In the photoelectric experiment, if we use a monochromatic light, the photoelectric current vs voltage curve is as shown. If work function of the metal is 2 eV, the power of light used in Watt is . (Assume number of photoelectrons emitted are 10−3% of number of photons incident on metal)
Answer» In the photoelectric experiment, if we use a monochromatic light, the photoelectric current vs voltage curve is as shown. If work function of the metal is $2 e V$ , the power of light used in Watt is . (Assume number of photoelectrons emitted are $10^{- 3} %$ of number of photons incident on metal)

9.	Charge is uniformly distributed in a space. The net flux passing through the surface of an imaginary cube of side a in the space is f. The net flux passing through the surface of an imaginary sphere of radius a in the space will be
Answer» Charge is uniformly distributed in a space. The net flux passing through the surface of an imaginary cube of side a in the space is f. The net flux passing through the surface of an imaginary sphere of radius a in the space will be

10.	Two lenses of power 15 D and −5 D are in contact. The focal length of combination is
Answer» Two lenses of power $15 D$ and $- 5 D$ are in contact. The focal length of combination is

11.	Two pulses traveling on the same string are describes by the function y1 and y2 generated from points A and B is in meter respectively y1=2(x−2t)2+1, y2=−2(x−4t)2+2 where x (in metre) and t (in sec) are in the distance between A & B is 1.5m, if the position where these two pulses will meet. (Shape of the pulse does not change) is x×10−1m Find x ___
Answer» Two pulses traveling on the same string are describes by the function $y_{1}$ and $y_{2}$ generated from points A and B is in meter respectively $y_{1} = \frac{2}{(x - 2 t)^{2} + 1}, y_{2} = \frac{- 2}{(x - 4 t)^{2} + 2}$ where x (in metre) and t (in sec) are in the distance between A & B is 1.5m, if the position where these two pulses will meet. (Shape of the pulse does not change) is $x \times 10^{- 1} m$ Find x ___

13.	A particle is projected under gravity with a speed v0. Using W-E theorem, find the speed of the particle as the function of vertical distance y.
Answer» A particle is projected under gravity with a speed $v_{0}$ . Using $W-E$ theorem, find the speed of the particle as the function of vertical distance $y$ .

14.	Interference fringes are obtained using 2 coherent sources whose intensities are in the ratio 9:4. Then ratio of the intensities of the bright and dark bands is
Answer» Interference fringes are obtained using 2 coherent sources whose intensities are in the ratio 9:4. Then ratio of the intensities of the bright and dark bands is

15.	The angular width of the central maximum in a single sit diffraction pattern is 60∘. The width of the slit is 1 μm. The slit is illuminated by monochromatic plane waves. If another slit of same width is made near it, Young's fringes can be observed on a screen placed at a distance 50 cm from the silts. If the observed fringe width is 1 cm, what is slit separation distance? (i.e. distance between the centres of each slit)
Answer» The angular width of the central maximum in a single sit diffraction pattern is $60^{\circ} .$ The width of the slit is $1 μ m$ . The slit is illuminated by monochromatic plane waves. If another slit of same width is made near it, Young's fringes can be observed on a screen placed at a distance $50 c m$ from the silts. If the observed fringe width is $1 c m,$ what is slit separation distance? (i.e. distance between the centres of each slit)

16.	A solid sphere of radius r made of a soft material of bulk modulus K is surrounded by a liquid in a cylindrical container. A massless piston of area a floats on the surface of the liquid, covering the entire crosssection of the cyindrical container. When a mass m is placed on the surface of the piston to compress the liquid, the fractional decrement in the radius of the sphere, (drr) is
Answer» A solid sphere of radius $r$ made of a soft material of bulk modulus $K$ is surrounded by a liquid in a cylindrical container. A massless piston of area $a$ floats on the surface of the liquid, covering the entire crosssection of the cyindrical container. When a mass $m$ is placed on the surface of the piston to compress the liquid, the fractional decrement in the radius of the sphere, $(\frac{d r}{r})$ is

17.	Two blocks A and B of equal masses are released from an inclined plane of inclination 45∘ at t=0 . Both the blocks are initially at rest. The coefficient of kinetic friction between the block A and the inclined plane is 0.2 while it is 0.3 for block B. Initially the block A is √2 m behind the block B. When and where from the position of A, front faces of both the blocks will come in a line? (Take g=10m/s2)
Answer» Two blocks $A$ and $B$ of equal masses are released from an inclined plane of inclination $45^{\circ}$ at $t = 0$ . Both the blocks are initially at rest. The coefficient of kinetic friction between the block $A$ and the inclined plane is $0.2$ while it is $0.3$ for block $B$ . Initially the block $A$ is $\sqrt{2} m$ behind the block $B$ . When and where from the position of A, front faces of both the blocks will come in a line? (Take $g = 10 m / s^{2})$

18.	The table gives the initial length l0, change in temperature ΔT and change in length Δl of four rods. Which rod has greatest coefficient of linear expansion Rodl0(m)ΔT(∘CΔl(m)A111001A211002A31.5503A42.5204
Answer» The table gives the initial length $l_{0}$ , change in temperature $Δ T$ and change in length $Δ l$ of four rods. Which rod has greatest coefficient of linear expansion $\begin{matrix} Rod & l_{0} (m) & Δ T (^{\circ} C & Δ l (m) A_{1} & 1 & 100 & 1 A_{2} & 1 & 100 & 2 A_{3} & 1.5 & 50 & 3 A_{4} & 2.5 & 20 & 4 \end{matrix}$

19.	Consider the two bobs as shown in the figure. The bobs are connected to the hinges through massless rods. If tA be the time taken by the bob A to reach the lowest position and tB be the time taken by the bob B to reach the lowest position. (Both bobs being released from rest from a horizontal position) then the ratio tAtB is
Answer» Consider the two bobs as shown in the figure. The bobs are connected to the hinges through massless rods. If $t_{A}$ be the time taken by the bob A to reach the lowest position and $t_{B}$ be the time taken by the bob B to reach the lowest position. (Both bobs being released from rest from a horizontal position) then the ratio $\frac{t_{A}}{t_{B}}$ is

20.	In an experiment of photoelectric effect the slope of cutoff voltage v/s frequency of incident light is found to be \(4.12 \times 10^{-15} Vs. Calculate the value of planks constant.
Answer» In an experiment of photoelectric effect the slope of cutoff voltage v/s frequency of incident light is found to be \(4.12 \times 10^{-15} Vs. Calculate the value of planks constant.

21.	A body of mass 2 kg is thrown vertically upwards with an initial velocity of 20 m/s. What will be its potential energy at the end of 2 s? Assume g=10 m/s2.
Answer» A body of mass 2 kg is thrown vertically upwards with an initial velocity of 20 m/s. What will be its potential energy at the end of 2 s? Assume $g = 10 m / s^{2}$ .

22.	A block of mass M is attached to the lower end of a vertical spring. The spring is hung from a ceiling and has force constant value k. The mass is released from rest with the spring initially unstretched. The maximum extension produced in the length of the spring will be
Answer» A block of mass $M$ is attached to the lower end of a vertical spring. The spring is hung from a ceiling and has force constant value $k$ . The mass is released from rest with the spring initially unstretched. The maximum extension produced in the length of the spring will be

23.	Figure shown below represents, parallel combination of two metallic slabs of same thickness having area of cross sections 2 m2 and 3 m2 respectively, connected to the same temperature difference. If the thermal conductivities of each slab is 300 W/m∘C, then equivalent thermal conductivity is (in W/m∘C)
Answer» Figure shown below represents, parallel combination of two metallic slabs of same thickness having area of cross sections $2 m^{2}$ and $3 m^{2}$ respectively, connected to the same temperature difference. If the thermal conductivities of each slab is $300 {W/m}^{\circ} C$ , then equivalent thermal conductivity is (in ${W/m}^{\circ} C$ )

24.	What are neutrinos and antineutrinos?
Answer» What are neutrinos and antineutrinos?

25.	If the power of a motor is 100kW, at what speed can it raise a load of 50000N.
Answer» If the power of a motor is 100kW, at what speed can it raise a load of 50000N.

26.	A mixture of 1 mole of nitrogen and 1 mole of hydrogen is in a container at room temperature. The ratio of root mean square speed of hydrogen and nitrogen molecules is
Answer» A mixture of $1$ mole of nitrogen and $1$ mole of hydrogen is in a container at room temperature. The ratio of root mean square speed of hydrogen and nitrogen molecules is

28.	A truck is moving with an acceleration of 2 m/s2 due to a constant horizontal force F. Suddenly, a hail storm starts with a constant rate of mass μ=20 kg/s getting deposited on the truck. Find the force needed to maintain the acceleration of the truck after 2 seconds. Take g=10 m/s2. Speed of the hailstorm is 2 m/s (perpendicular to the velocity of the truck) and mass of the truck is initially m0=50 kg.
Answer» A truck is moving with an acceleration of $2 {m/s}^{2}$ due to a constant horizontal force $F$ . Suddenly, a hail storm starts with a constant rate of mass $μ = 20 kg/s$ getting deposited on the truck. Find the force needed to maintain the acceleration of the truck after $2$ seconds. Take $g = 10 {m/s}^{2} .$ Speed of the hailstorm is $2 m/s$ (perpendicular to the velocity of the truck) and mass of the truck is initially $m_{0} = 50 kg$ .

29.	The resistivity of potentiometer wire is 10−7 Ωm and its area of cross-section is 10−6 m2. When a current i=0.1 A flows through the wire, its potential gradient is
Answer» The resistivity of potentiometer wire is $10^{- 7} Ω m$ and its area of cross-section is $10^{- 6} m^{2}$ . When a current $i = 0.1 A$ flows through the wire, its potential gradient is

Explore topic-wise InterviewSolutions in Current Affairs.

Figure shows a quarter circle. A particle moves from B to O with 5 m/s, from O to A with 7 m/s. With what speed the particle should move from A to B so that average speed for total journey is 6 m/s?

For the cell: Tl(s)|Tl+(0.001M)||Cu2+(0.1M)|Cu(s): Ecell = 0.83 V at 298 K, The cell potential can be increased by

Two plates 1 and 2 move with velocities −v and 2v respectively. If the sphere does not slide relative to the plates, assuming the masses of each body as m, find the kinetic energy of the system (plate+sphere).

A rectangular wire loop of sides a and b is placed in a non – uniform magnetic field which varies with x as B = kx where k is a constant. The magnetic field is directed perpendicular to the plane of the coil as shown in fig. The magnetic flux through the coil is

Range of frequencies allotted for commercial FM radio broadcast is

A plank of mass M is held at an angle α to the horizontal on two fixed poles A &amp; B as shown in figure. To keep the plank at rest, a person of mass m moves on the plank with some acceleration (neglect friction between plank &amp; poles). Mark the correct statement for this situation

In the photoelectric experiment, if we use a monochromatic light, the photoelectric current vs voltage curve is as shown. If work function of the metal is 2 eV, the power of light used in Watt is . (Assume number of photoelectrons emitted are 10−3% of number of photons incident on metal)

Charge is uniformly distributed in a space. The net flux passing through the surface of an imaginary cube of side a in the space is f. The net flux passing through the surface of an imaginary sphere of radius a in the space will be

Two lenses of power 15 D and −5 D are in contact. The focal length of combination is

A particle is projected under gravity with a speed v0. Using W-E theorem, find the speed of the particle as the function of vertical distance y.

Interference fringes are obtained using 2 coherent sources whose intensities are in the ratio 9:4. Then ratio of the intensities of the bright and dark bands is

The table gives the initial length l0, change in temperature ΔT and change in length Δl of four rods. Which rod has greatest coefficient of linear expansion Rodl0(m)ΔT(∘CΔl(m)A111001A211002A31.5503A42.5204

In an experiment of photoelectric effect the slope of cutoff voltage v/s frequency of incident light is found to be \(4.12 \times 10^{-15} Vs. Calculate the value of planks constant.

A body of mass 2 kg is thrown vertically upwards with an initial velocity of 20 m/s. What will be its potential energy at the end of 2 s? Assume g=10 m/s2.

A block of mass M is attached to the lower end of a vertical spring. The spring is hung from a ceiling and has force constant value k. The mass is released from rest with the spring initially unstretched. The maximum extension produced in the length of the spring will be

What are neutrinos and antineutrinos?

If the power of a motor is 100kW, at what speed can it raise a load of 50000N.

A mixture of 1 mole of nitrogen and 1 mole of hydrogen is in a container at room temperature. The ratio of root mean square speed of hydrogen and nitrogen molecules is

The given setup is in equilibrium springs were in natural length before force was applied. If I have to replace the above setup by 1 block and 1 spring then what will be the spring constant of that new spring, such that the block is displaced by the same amount previously by the applied force.

The resistivity of potentiometer wire is 10−7 Ωm and its area of cross-section is 10−6 m2. When a current i=0.1 A flows through the wire, its potential gradient is

The momentum in mechanics is expressed as m x v. The analogous expression in electricity is

A circular arc has a radius of 0.1m. The angle it subtends at the Centreis π6 . If the charge it carries is 10C. what is the linear charge density of the wire?

Explain why Photoelectric effect cannot be explained on the basis of wave nature of light.

What is the moment of inertia of a hollow sphere of radius 3 m and mass 2 kg about an axis passing through the geometric centre of the sphere?

The graph in figure given below represents the velocity-time graph of a particle, starting from rest at point P. Find the time when particle will reach point P again.

P is a point on the axis of a ring with Centre 0 and radius 0.1m. The ring is uniformly charged with linear charge density 0.5 c/m. Given OP = 0.1 m, the electric field at P is approximately ten to the power ____ in SI units. ___

A point charge produces an electric field of magnitude 5.0 NC−1 at a distance of 40 cm from it. What is the magnitude of charge?

A particle of mass 200 g is projected from origin O with speed 10 m/s at an angle 60∘ with positive x− axis. Find the magnitude of angular momentum of particle after 5 sec about O before the particle strikes the ground again. (Take g=10 m/s2)

Find the angular momentum of the particle of mass 0.05 kg, position vector →r=(8^i+4^j) m and moving with a velocity 2^i m/s about the origin.

Find the value of 'p' for which the vectors 3^i+2^j+9^k and ^i−2p^j+3^k are parallel.

The bond dissociation energy of C - H in CH4 from the equation C(g) + 4H(g) ⟶ CH4(g) ΔH = -397.8 Kcal is

State the factors on which the speed of a wave travelling along a stretched ideal string depends.

A wire increases by 10−3 times of its length when a stress of 1×108 Nm−2 is applied to it in the longitudinal direction. Ratio of longitudinal stress and longitudinal strain in the wire is

P−T diagram of one mole of an ideal monatomic gas is shown. Process AB and CD are adiabatic. Work done in the complete cycle is

The focal length f of a mirror is given by 1f=1u+1v where u and v represent object and image distances respectively. The fractional error in 'f' is given by

A particle performs uniform circular motion with an angular momentum L. If the angular frequency f of the particle is doubled, and kinetic energy is halved, its angular momentum becomes

A cubical beaker of edge length 10 cm is filled with a liquid of surface tension 0.075 N/m. Force across an imaginary diagonal on the surface of the liquid is

A body having zero velocity will necessarily have zero acceleration. true or false??

A man is travelling at 10.8 km h−1 on a rainy day. He holds an umbrella at an angle 37∘ to the vertical to protect himself from the rain which is falling vertically downwards. What is the magnitude of velocity of the rain?

A plank of mass M is held at an angle α to the horizontal on two fixed poles A & B as shown in figure. To keep the plank at rest, a person of mass m moves on the plank with some acceleration (neglect friction between plank & poles). Mark the correct statement for this situation

P is a point on the axis of a ring with Centre 0 and radius 0.1m. The ring is uniformly charged with linear charge density 0.5 c/m. Given OP = 0.1 m, the electric field at P is approximately ten to the power __ in SI units. _

30.	The momentum in mechanics is expressed as m x v. The analogous expression in electricity is
Answer» The momentum in mechanics is expressed as $m$ x $v$ . The analogous expression in electricity is

31.	A circular arc has a radius of 0.1m. The angle it subtends at the Centreis π6 . If the charge it carries is 10C. what is the linear charge density of the wire?
Answer» A circular arc has a radius of 0.1m. The angle it subtends at the Centreis $\frac{π}{6}$ . If the charge it carries is 10C. what is the linear charge density of the wire?

32.	The cross section of a dam wall is an arc of a circle of radius R=20m subtending an angle of θ=60∘ at the centre of the circle. The centre (O) of the circle lies on the water surface. The width of the dam [i.e. dimension perpendicular to the figure] is b =10 m. Neglect atmospheric pressure. The horizontal component of force applied by water on the curved dam wall is x×107N. The value of x is . (Answer upto two digit after the decimal point)
Answer» The cross section of a dam wall is an arc of a circle of radius $R = 20 m$ subtending an angle of $θ = 60^{\circ}$ at the centre of the circle. The centre $(O)$ of the circle lies on the water surface. The width of the dam [i.e. dimension perpendicular to the figure] is b =10 m. Neglect atmospheric pressure. The horizontal component of force applied by water on the curved dam wall is $x \times 10^{7} N$ . The value of $x$ is . (Answer upto two digit after the decimal point)

33.	Explain why Photoelectric effect cannot be explained on the basis of wave nature of light.
Answer» Explain why Photoelectric effect cannot be explained on the basis of wave nature of light.

34.	What is the moment of inertia of a hollow sphere of radius 3 m and mass 2 kg about an axis passing through the geometric centre of the sphere?
Answer» What is the moment of inertia of a hollow sphere of radius $3 m$ and mass $2 kg$ about an axis passing through the geometric centre of the sphere?

35.	The graph in figure given below represents the velocity-time graph of a particle, starting from rest at point P. Find the time when particle will reach point P again.
Answer» The graph in figure given below represents the velocity-time graph of a particle, starting from rest at point $P$ . Find the time when particle will reach point $P$ again.

36.	P is a point on the axis of a ring with Centre 0 and radius 0.1m. The ring is uniformly charged with linear charge density 0.5 c/m. Given OP = 0.1 m, the electric field at P is approximately ten to the power ____ in SI units. ___
Answer» P is a point on the axis of a ring with Centre 0 and radius 0.1m. The ring is uniformly charged with linear charge density 0.5 c/m. Given OP = 0.1 m, the electric field at P is approximately ten to the power ____ in SI units. ___

37.	A point charge produces an electric field of magnitude 5.0 NC−1 at a distance of 40 cm from it. What is the magnitude of charge?
Answer» A point charge produces an electric field of magnitude 5.0 $N C^{- 1}$ at a distance of 40 cm from it. What is the magnitude of charge?

38.	A column of mercury of length 10 cm is contained in the middle of a horizontal tube of length 1m which is closed at both the ends. The two equal lengths contain air at standard atmospheric pressure of 0.76 m of mercury. The tube is now turned to vertical position. By what approximate distance (in cm) will the column of mercury be displaced?
Answer» A column of mercury of length 10 cm is contained in the middle of a horizontal tube of length 1m which is closed at both the ends. The two equal lengths contain air at standard atmospheric pressure of 0.76 m of mercury. The tube is now turned to vertical position. By what approximate distance (in cm) will the column of mercury be displaced?

39.	A particle of mass 200 g is projected from origin O with speed 10 m/s at an angle 60∘ with positive x− axis. Find the magnitude of angular momentum of particle after 5 sec about O before the particle strikes the ground again. (Take g=10 m/s2)
Answer» A particle of mass $200 g$ is projected from origin $O$ with speed $10 m/s$ at an angle $60^{\circ}$ with positive $x -$ axis. Find the magnitude of angular momentum of particle after $5 sec$ about $O$ before the particle strikes the ground again. (Take $g = 10 {m/s}^{2}$ )