50278 + Interview Questions in Physics

1.	A concave mirror of radius of curvature 10 cm is cut into two equal parts, slightly separated and placed in front of a monochromatic line source S of wavelength 2000 ^A as shown in figure. Consider only interference in reflected light after first reflection from mirrors. Assume direct light from S is blocked from reaching the screen Assume A is the position of first order maxima on the screen. Now the point object is moved away from normal to screen with constant speed, then:
Answer» A concave mirror of radius of curvature 10 cm is cut into two equal parts, slightly separated and placed in front of a monochromatic line source S of wavelength 2000 $^A$ as shown in figure. Consider only interference in reflected light after first reflection from mirrors. Assume direct light from S is blocked from reaching the screen Assume A is the position of first order maxima on the screen. Now the point object is moved away from normal to screen with constant speed, then:

1.

A concave mirror of radius of curvature 10 cm is cut into two equal parts, slightly separated and placed in front of a monochromatic line source S of wavelength 2000 ^A as shown in figure. Consider only interference in reflected light after first reflection from mirrors. Assume direct light from S is blocked from reaching the screen Assume A is the position of first order maxima on the screen. Now the point object is moved away from normal to screen with constant speed, then:

Answer»

A concave mirror of radius of curvature 10 cm is cut into two equal parts, slightly separated and placed in front of a monochromatic line source S of wavelength 2000 $^A$ as shown in figure. Consider only interference in reflected light after first reflection from mirrors. Assume direct light from S is blocked from reaching the screen

Assume A is the position of first order maxima on the screen. Now the point object is moved away from normal to screen with constant speed, then:

2.	A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is connected in parallel. The total electrostatic energy of resulting system is
Answer» A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is connected in parallel. The total electrostatic energy of resulting system is

3.	In a young's double slit experiment, the distance between slits S1 and S2 is d and distance of slit plane from the screen is D(>>d). The point source of light (s) is placed a distance d2 below the principal axis and the slits S1 and S2 are located symmetrically with respect to the principal axis of the lens. Focal length of the lens is f(>>d). The distance of the central maxima of the fringe pattern from the centre (O) of the screen is found to be Ddxf. The value of 4x is
Answer» In a young's double slit experiment, the distance between slits $S_{1}$ and $S_{2}$ is $d$ and distance of slit plane from the screen is $D (>> d)$ . The point source of light (s) is placed a distance $\frac{d}{2}$ below the principal axis and the slits $S_{1}$ and $S_{2}$ are located symmetrically with respect to the principal axis of the lens. Focal length of the lens is $f (>> d)$ . The distance of the central maxima of the fringe pattern from the centre $(O)$ of the screen is found to be $\frac{D d}{x f}$ . The value of $4 x$ is

4.	A ray of light is incident on a glass sphere of refractive index √3 at an angle of 60∘ as shown in the figure. The angle by which it is deviated as it comes off sphere is
Answer» A ray of light is incident on a glass sphere of refractive index $\sqrt{3}$ at an angle of $60^{\circ}$ as shown in the figure. The angle by which it is deviated as it comes off sphere is

5.	A voltage of peak value 283 V and varying frequency is applied to a series LCR combination in which R=3 Ω, L=25 mH and C=400 μF. The frequency (in Hz) of the source at which maximum power is dissipated in the above circuit is
Answer» A voltage of peak value $283 V$ and varying frequency is applied to a series $L C R$ combination in which $R = 3$ $Ω$ , $L = 25 m H$ and $C = 400$ $μ F$ . The frequency (in $H z$ ) of the source at which maximum power is dissipated in the above circuit is

6.	A spherical balloon contains air at temperature To and pressure Po. The balloon material is such that the instantaneous pressure inside is proportional to the square of the diameter. When the volume of the balloon doubles as a result of heat transfer, the expansion follows the law PV−ab where a and b are co-prime. Find the sum of a and b (Answer upto two digit after the decimal point)
Answer» A spherical balloon contains air at temperature $T_{o}$ and pressure $P_{o}$ . The balloon material is such that the instantaneous pressure inside is proportional to the square of the diameter. When the volume of the balloon doubles as a result of heat transfer, the expansion follows the law $P V^{\frac{- a}{b}}$ where $a$ and $b$ are co-prime. Find the sum of $a$ and $b$ (Answer upto two digit after the decimal point)

7.	A spring balance reads W1 when a ball is suspended from it. A weighing machine reads W2when a tank of liquid is kept on it. When the ball is immersed in the liquid, the spring balance reads W3 and the weighing machine reads W4. Then, which of the following are not correct?
Answer» A spring balance reads $W_{1}$ when a ball is suspended from it. A weighing machine reads $W_{2}$ when a tank of liquid is kept on it. When the ball is immersed in the liquid, the spring balance reads $W_{3}$ and the weighing machine reads $W_{4}$ . Then, which of the following are not correct?

9.	A flexible wire bent in the form of a circular coil, is placed in a uniform magnetic field perpendicular to the plane of the coil. The radius of the coil changes as shown in Fig. The graph of magnitude of induced emf in the coil is represented by
Answer» A flexible wire bent in the form of a circular coil, is placed in a uniform magnetic field perpendicular to the plane of the coil. The radius of the coil changes as shown in Fig. The graph of magnitude of induced emf in the coil is represented by

10.	PSLV launches a rocket which is ejecting gas with a speed of 100 m/s w.r.t the rocket and the rate of ejection of gas from the rocket is 400 kg/s. If the mass of the rocket is 2000 kg, calculate the initial acceleration of the rocket. [Take g=10 m/s2]
Answer» $P S L V$ launches a rocket which is ejecting gas with a speed of $100 m/s$ w.r.t the rocket and the rate of ejection of gas from the rocket is $400 kg/s$ . If the mass of the rocket is $2000 kg$ , calculate the initial acceleration of the rocket. [Take $g = 10 {m/s}^{2}$ ]

11.	A particle of mass m is at rest at the origin at time t=0. It is subjected to a force F(t)=F0e−bt in the x−direction. It's speed v(t) is depicted by which of the following curves?
Answer» A particle of mass $m$ is at rest at the origin at time $t = 0$ . It is subjected to a force $F (t) = F_{0} e^{- b t}$ in the $x -$ direction. It's speed $v (t)$ is depicted by which of the following curves?

12.	The total acceleration of a particle in circular motion is 25 ms−2. If the speed of the particle decreases at a rate of 15 ms−2. If radius of the path of the particle is r=2 m, the angular speed ω of the particle relative to the centre of the circle is
Answer» The total acceleration of a particle in circular motion is $25 m s^{- 2} .$ If the speed of the particle decreases at a rate of $15 m s^{- 2} .$ If radius of the path of the particle is $r = 2 m$ , the angular speed $ω$ of the particle relative to the centre of the circle is

13.	A compound microscope has a magnifying power of 100 when the image is formed at infinity. The objective has a focal length of 0.5 cm and the tube length is 6.5 cm. Find the focal length of the eyepiece.
Answer» A compound microscope has a magnifying power of 100 when the image is formed at infinity. The objective has a focal length of 0.5 cm and the tube length is 6.5 cm. Find the focal length of the eyepiece.

14.	A force →F=−k(y^i+x^j) (where k is a positive constant) acts on a particle moving in the x−y plane. Starting from the origin, the particle is taken along the positive x−axis to the point (a,0) and then parallel to the y−axis to point (a,a). Then, total work done by the force is
Answer» A force $\to F = - k (y^i + x^j)$ (where $k$ is a positive constant) acts on a particle moving in the $x - y$ plane. Starting from the origin, the particle is taken along the positive $x -$ axis to the point $(a, 0)$ and then parallel to the $y -$ axis to point $(a, a)$ . Then, total work done by the force is

16.	A rod of length 10 ft slides with ends on the co-ordinate Axes. if the end on x axis moves with constant velocity of 2 feet/minute, find the velocity of its middle point at the instant the rod makes an angle of 30° with x axis.
Answer» A rod of length 10 ft slides with ends on the co-ordinate Axes. if the end on x axis moves with constant velocity of 2 feet/minute, find the velocity of its middle point at the instant the rod makes an angle of 30° with x axis.

18.	Is the other name of Kirchhoff's voltage law called Kirchhoff's loop law?
Answer» Is the other name of Kirchhoff's voltage law called Kirchhoff's loop law?

15.	At t=0, a particle starts from (1,0) and moves towards positive x−axis with speed of v=3t2+2t m/s. The final position of the particle as a function of time is
Answer» At $t = 0$ , a particle starts from $(1, 0)$ and moves towards positive $x -$ axis with speed of $v = 3 t^{2} + 2 t m/s$ . The final position of the particle as a function of time is

17.	If the speed of a particle is given as v=6t2+2t+5 m/s, the speed of the particle at 4 sec and the average speed in 4 sec respectively is
Answer» If the speed of a particle is given as $v = 6 t^{2} + 2 t + 5 m/s$ , the speed of the particle at $4 sec$ and the average speed in $4 sec$ respectively is

19.	A particle starts from rest with uniform acceleration a. Its velocity after n seconds is v. The displacement of the particle in the last two seconds is?
Answer» A particle starts from rest with uniform acceleration a. Its velocity after n seconds is v. The displacement of the particle in the last two seconds is?

22.	What can be the value of the vector sum of the forces 10N and 6N ?
Answer» What can be the value of the vector sum of the forces 10N and 6N ?

23.	A cell of internal resistance r is connected to a load of resistance R. Energy is dissipated in the load but some thermal energy is also wasted in the cell. The efficiency of such an arrangement is found from the expression Energy dissipated in the loadEnergy dissipated in the complete circuit Which of the following gives the efficiency in this case?
Answer» A cell of internal resistance $r$ is connected to a load of resistance $R$ . Energy is dissipated in the load but some thermal energy is also wasted in the cell. The efficiency of such an arrangement is found from the expression $\frac{Energy dissipated in the load}{Energy dissipated in the complete circuit}$ Which of the following gives the efficiency in this case?

24.	A projectile is projected from the base of an inclined plane of inclination 'α'. The angle of projection of the projectile with the ground is θ. If it strikes the incline plane at it's maximum height from the ground, then, (assume the plane of motion contains the line of greatest slope on the incline plane)
Answer» A projectile is projected from the base of an inclined plane of inclination ' $α$ '. The angle of projection of the projectile with the ground is $θ$ . If it strikes the incline plane at it's maximum height from the ground, then, (assume the plane of motion contains the line of greatest slope on the incline plane)

25.	When a body tied at the end of a string is performing uniform circular motion in a horizontal plane, which force balances the weight of the body?
Answer» When a body tied at the end of a string is performing uniform circular motion in a horizontal plane, which force balances the weight of the body?

26.	At time t = 0, a battery of 10 V is connected across points A and B in the given circuit. If the capacitors have no charge initially, at what time (in seconds) does the voltage across them become 4 V? [Take: In 5 = 1.6, In 3 = 1.1]
Answer» At time t = 0, a battery of 10 V is connected across points A and B in the given circuit. If the capacitors have no charge initially, at what time (in seconds) does the voltage across them become 4 V? [Take: In 5 = 1.6, In 3 = 1.1]

27.	Uniform rod AB of mass 3 kg and length 2 m is hinged at end A in horizontal position as shown in the figure. The other end is connected to a block of mass 1 kg through a massless string. The pulley is smooth and massless. Find the angular acceleration of the rod about the hinge just after release. (Take anti-clockwise rotation positive)
Answer» Uniform rod $A B$ of mass $3 kg$ and length $2 m$ is hinged at end $A$ in horizontal position as shown in the figure. The other end is connected to a block of mass $1 kg$ through a massless string. The pulley is smooth and massless. Find the angular acceleration of the rod about the hinge just after release. (Take anti-clockwise rotation positive)

28.	A ball is thrown vertically upwards from a tower with a velocity 20 m/s. The ball strikes theearth after 5 sec of trowing. What is the height of the tower? What will be the velocity of ball while stroking the earth? (g=9.8m/s2)
Answer» A ball is thrown vertically upwards from a tower with a velocity 20 m/s. The ball strikes theearth after 5 sec of trowing. What is the height of the tower? What will be the velocity of ball while stroking the earth? (g=9.8m/s2)

Explore topic-wise InterviewSolutions in Current Affairs.

A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is connected in parallel. The total electrostatic energy of resulting system is

A ray of light is incident on a glass sphere of refractive index √3 at an angle of 60∘ as shown in the figure. The angle by which it is deviated as it comes off sphere is

A voltage of peak value 283 V and varying frequency is applied to a series LCR combination in which R=3 Ω, L=25 mH and C=400 μF. The frequency (in Hz) of the source at which maximum power is dissipated in the above circuit is

A spring balance reads W1 when a ball is suspended from it. A weighing machine reads W2when a tank of liquid is kept on it. When the ball is immersed in the liquid, the spring balance reads W3 and the weighing machine reads W4. Then, which of the following are not correct?

The figure shows two positions A and B at the same height h above the ground. If the maximum height of the projectile is H, then determine the time t elapsed between the positions A and B in terms of H.

A flexible wire bent in the form of a circular coil, is placed in a uniform magnetic field perpendicular to the plane of the coil. The radius of the coil changes as shown in Fig. The graph of magnitude of induced emf in the coil is represented by

PSLV launches a rocket which is ejecting gas with a speed of 100 m/s w.r.t the rocket and the rate of ejection of gas from the rocket is 400 kg/s. If the mass of the rocket is 2000 kg, calculate the initial acceleration of the rocket. [Take g=10 m/s2]

A particle of mass m is at rest at the origin at time t=0. It is subjected to a force F(t)=F0e−bt in the x−direction. It's speed v(t) is depicted by which of the following curves?

The total acceleration of a particle in circular motion is 25 ms−2. If the speed of the particle decreases at a rate of 15 ms−2. If radius of the path of the particle is r=2 m, the angular speed ω of the particle relative to the centre of the circle is

A compound microscope has a magnifying power of 100 when the image is formed at infinity. The objective has a focal length of 0.5 cm and the tube length is 6.5 cm. Find the focal length of the eyepiece.

A force →F=−k(y^i+x^j) (where k is a positive constant) acts on a particle moving in the x−y plane. Starting from the origin, the particle is taken along the positive x−axis to the point (a,0) and then parallel to the y−axis to point (a,a). Then, total work done by the force is

At t=0, a particle starts from (1,0) and moves towards positive x−axis with speed of v=3t2+2t m/s. The final position of the particle as a function of time is

A rod of length 10 ft slides with ends on the co-ordinate Axes. if the end on x axis moves with constant velocity of 2 feet/minute, find the velocity of its middle point at the instant the rod makes an angle of 30° with x axis.

If the speed of a particle is given as v=6t2+2t+5 m/s, the speed of the particle at 4 sec and the average speed in 4 sec respectively is

Is the other name of Kirchhoff's voltage law called Kirchhoff's loop law?

A particle starts from rest with uniform acceleration a. Its velocity after n seconds is v. The displacement of the particle in the last two seconds is?

For a particle in uniform circular motion the acceleration →a at a point P(R,θ)on the circle of radius R is (here θ is measured from the x-axis)

The period of a simple pendulum is doubled, when

What can be the value of the vector sum of the forces 10N and 6N ?

When a body tied at the end of a string is performing uniform circular motion in a horizontal plane, which force balances the weight of the body?

At time t = 0, a battery of 10 V is connected across points A and B in the given circuit. If the capacitors have no charge initially, at what time (in seconds) does the voltage across them become 4 V? [Take: In 5 = 1.6, In 3 = 1.1]

A ball is thrown vertically upwards from a tower with a velocity 20 m/s. The ball strikes theearth after 5 sec of trowing. What is the height of the tower? What will be the velocity of ball while stroking the earth? (g=9.8m/s2)

The energy of an electromagnetic radiation is 3 × 10−12 ergs. What is its wavelength in nanometer?(h = 6.625 × 10−27 erg.Sec, C = 3 × 1010 cm.Sec−1)

What is meant by resistance?

An ideal fluid flows in the pipe as shown in the figure. The pressure in the fluid at the bottom P2 is the same as it is at the top P1. If the velocity of the top is v1=2 m/s. Then the ratio of areas A1A2 is

Why sign convection of outwards is cross and inwards in dot?

After a totally inelastic collision, two objects of the same masses and same initial speeds are found to move together at half of their initial speeds as shown in figure below. If α=30∘, then the angle between the initial velocities of the objects is

A coil in the shape of an equilateral triangle of side l is suspended between the pole pieces of a permanent magnet, such that magnetic field of intensity B is along the plane of the coil. If due to a current I in the triangle, a torque τ acts on it, then side l of the triangle is :

In an RLC circuit at resonance power factor is A. 0.5 B. -0.5 C. 1 D. 0

An aluminium rod of length 3.14 m is of square cross-section 3.14×3.14 mm2. What should be the radius of 1 m long another rod of same material to have equal resistance

A block of ice with mass m falls into a lake. After impact, a mass of ice m5 melts. Both the block of ice and the lake have a temperature of 0∘C. If L represents the heat of fusion, the minimum distance the ice fell before striking the surface is

The horizontal range and maximum height attained by a projectile are R and H, respectively. If a constant horizontal acceleration a=g4 is imparted to the projectile due to wind, then its horizontal range and maximum height will be

Two stars, each of mass m and radius R, are approaching each other for a head-on collision. They start approaching each other when their separation is r &gt;&gt; R. If their speed at this separation is negligible, the speed with which they collide would be

At 00C, ice and water are in equilibrium and ΔH0=6.00 kJ/mol for the process H2O(s)⇋H2O(l). The value of ΔS0 for the conversion of ice to liquid water is:

A flywheel has moment of inertia 2 kgm2. What constant torque is required to increase its speed from 4 rps to 12 rps in 8 sec?

A man moving at 4 km per hour towards East finds the raindrops falling vertically at 4 km per hour. What is the actual speed and direction of rain?

For a moving ball of cricket, the correct statement about de-Broglie wavelength is

A car, starting from rest, accelerates at the rate f through a distance S, then continuous at constant speed for time t and then decelerates at the rate f2 to come to rest. If the total distance traversed is 15 s, then

The magnetic field at a point inside a 2.0 mH inductor- coil becomes 0.80 of its maximum value in 20μs whent the inductor is joined to a battery . Find the resistance of the circuit.

When the base current in a transistor is changed from 30 μA to 80 μA, the collector current is changed from 1.0 mA to 3.5 mA. Find the current gain β.

Find the maximum Coulomb force that can act on the electron due to the nucleus in a hydrogen atom.

The curves a, b, c and d shows the variation between the applied potential difference (V) and the photoelectric current (i) at two different intensities of light (I1&gt;I2). Which of the following figure is correct?

Two stars, each of mass m and radius R, are approaching each other for a head-on collision. They start approaching each other when their separation is r >> R. If their speed at this separation is negligible, the speed with which they collide would be

The curves a, b, c and d shows the variation between the applied potential difference (V) and the photoelectric current (i) at two different intensities of light (I1>I2). Which of the following figure is correct?

29.	The energy of an electromagnetic radiation is 3 × 10−12 ergs. What is its wavelength in nanometer?(h = 6.625 × 10−27 erg.Sec, C = 3 × 1010 cm.Sec−1)
Answer» The energy of an electromagnetic radiation is $3 \times 10^{- 12} e r g s$ . What is its wavelength in nanometer?( $h$ = $6.625 \times 10^{- 27} e r g . S e c$ , $C$ = $3 \times 10^{10} c m . S e c^{- 1})$

30.	What is meant by resistance?
Answer» What is meant by resistance?

31.	An ideal fluid flows in the pipe as shown in the figure. The pressure in the fluid at the bottom P2 is the same as it is at the top P1. If the velocity of the top is v1=2 m/s. Then the ratio of areas A1A2 is
Answer» An ideal fluid flows in the pipe as shown in the figure. The pressure in the fluid at the bottom $P_{2}$ is the same as it is at the top $P_{1}$ . If the velocity of the top is $v_{1} = 2 m/s$ . Then the ratio of areas $\frac{A_{1}}{A_{2}}$ is

32.	Why sign convection of outwards is cross and inwards in dot?
Answer» Why sign convection of outwards is cross and inwards in dot?

33.	After a totally inelastic collision, two objects of the same masses and same initial speeds are found to move together at half of their initial speeds as shown in figure below. If α=30∘, then the angle between the initial velocities of the objects is
Answer» After a totally inelastic collision, two objects of the same masses and same initial speeds are found to move together at half of their initial speeds as shown in figure below. If $α = 30^{\circ}$ , then the angle between the initial velocities of the objects is

34.	A coil in the shape of an equilateral triangle of side l is suspended between the pole pieces of a permanent magnet, such that magnetic field of intensity B is along the plane of the coil. If due to a current I in the triangle, a torque τ acts on it, then side l of the triangle is :
Answer» A coil in the shape of an equilateral triangle of side $l$ is suspended between the pole pieces of a permanent magnet, such that magnetic field of intensity $B$ is along the plane of the coil. If due to a current $I$ in the triangle, a torque $τ$ acts on it, then side $l$ of the triangle is :

35.	A train is moving with a velocity of 100 km/hr. Car A is traveling with velocity 100km/hr w.r.t. train in the opposite direction. Car B is traveling at the rate of 100 km/hr on the ground alongside the train. A man X is sitting inside the train and a man Y is standing outside the train and watching the entire episode. With respect to who is the car A at rest?
Answer» A train is moving with a velocity of 100 km/hr. Car A is traveling with velocity 100km/hr w.r.t. train in the opposite direction. Car B is traveling at the rate of 100 km/hr on the ground alongside the train. A man X is sitting inside the train and a man Y is standing outside the train and watching the entire episode. With respect to who is the car A at rest?

36.	In an RLC circuit at resonance power factor is A. 0.5 B. -0.5 C. 1 D. 0
Answer» In an RLC circuit at resonance power factor is A. 0.5 B. -0.5 C. 1 D. 0

37.	An aluminium rod of length 3.14 m is of square cross-section 3.14×3.14 mm2. What should be the radius of 1 m long another rod of same material to have equal resistance
Answer» An aluminium rod of length 3.14 m is of square cross-section $3.14 \times 3.14 m m^{2}$ . What should be the radius of 1 m long another rod of same material to have equal resistance

38.	A block of ice with mass m falls into a lake. After impact, a mass of ice m5 melts. Both the block of ice and the lake have a temperature of 0∘C. If L represents the heat of fusion, the minimum distance the ice fell before striking the surface is
Answer» A block of ice with mass $m$ falls into a lake. After impact, a mass of ice $\frac{m}{5}$ melts. Both the block of ice and the lake have a temperature of $0^{\circ} C$ . If $L$ represents the heat of fusion, the minimum distance the ice fell before striking the surface is