50278 + Interview Questions in Physics

1.	A proton and an α - particle enter a uniform magnetic field perpendicularly with same speed. If proton takes 25 μs to make 5 revolutions, then the time period of the α - particle would be equal to
Answer» A proton and an $α$ - particle enter a uniform magnetic field perpendicularly with same speed. If proton takes $25 μ s$ to make $5$ revolutions, then the time period of the $α$ - particle would be equal to

Discussion

2.	Three capacitors each having capacitance C=2 μF are connected with a battery of e.m.f. 30 V as shown in the figure. When the switch S is closed, the extra amount of charge flown through the battery is
Answer» Three capacitors each having capacitance $C = 2 μ F$ are connected with a battery of e.m.f. $30 V$ as shown in the figure. When the switch $S$ is closed, the extra amount of charge flown through the battery is

Discussion

3.	Wavelength of light of frequency 100 Hz is,
Answer» Wavelength of light of frequency $100$ $H z$ is,

Discussion

4.	Two mirrors are inclined at an angle 60∘. If an object is placed symmetrically between them, then the number of images formed will be
Answer» Two mirrors are inclined at an angle $60^{\circ}$ . If an object is placed symmetrically between them, then the number of images formed will be

Discussion

5.	Moment of inertia of uniform rod of mass M and length L about an axis through its centre and perpendicular to its length is given by ML212. Now consider one such rod pivoted at its centre, free to rotate in a vertical plane. The rod is at rest in the vertical position. A bullet of mass M moving horizontally at a speed v strikes and embedded in one end of the rod. The angular velocity of the rod just after the collision will be
Answer» Moment of inertia of uniform rod of mass M and length L about an axis through its centre and perpendicular to its length is given by $\frac{M L^{2}}{12}$ . Now consider one such rod pivoted at its centre, free to rotate in a vertical plane. The rod is at rest in the vertical position. A bullet of mass M moving horizontally at a speed v strikes and embedded in one end of the rod. The angular velocity of the rod just after the collision will be

Discussion

6.	A car 2 m long and 3 m wide is moving at 13 m/s when a bullet hits it in a direction making an angle 37∘ with car as seen from street. The bullet enters one edge of the car at the corner and passes out diagonally opposite corner. Time for bullet to cross car is (Write upto two digits after the decimal point.)
Answer» A car 2 m long and 3 m wide is moving at 13 m/s when a bullet hits it in a direction making an angle $37^{\circ}$ with car as seen from street. The bullet enters one edge of the car at the corner and passes out diagonally opposite corner. Time for bullet to cross car is (Write upto two digits after the decimal point.)

Discussion

7.	A particle moves according to the law x = a cos πt2. The distance covered by it in the time interval between t = 0 to t = 3 s is
Answer» A particle moves according to the law x = a cos $\frac{π t}{2} .$ The distance covered by it in the time interval between t = 0 to t = 3 s is

Discussion

8.	One twirls a circular ring (of mass M and radius R ) near the tip of one's finger as shown in Figure 1.In the process the finger never loses contact with the inner rim of the ring. The finger traces out the surface of a cone, shown by the dotted line. The radius of the path traced out by the point where the ring and the finger is in contact is r. The finger rotates with an angular velocity ω0. The rotating ring rolls without slipping on the outside of a smaller circle described by the point where the ring and the finger is in contact (Figure 2 ). The cocficieicient of friction between the ring and the finger is μ and the acceleration due to gravity is gThe minimum value of ω0 below which the ring will drop down is
Answer» One twirls a circular ring (of mass $M$ and radius $R$ ) near the tip of one's finger as shown in Figure $1 . I n$ the process the finger never loses contact with the inner rim of the ring. The finger traces out the surface of a cone, shown by the dotted line. The radius of the path traced out by the point where the ring and the finger is in contact is $r$ . The finger rotates with an angular velocity $ω_{0}$ . The rotating ring rolls without slipping on the outside of a smaller circle described by the point where the ring and the finger is in contact (Figure 2 ). The cocficieicient of friction between the ring and the finger is $μ$ and the acceleration due to gravity is $g$ The minimum value of $ω_{0}$ below which the ring will drop down is

Discussion

9.	For a wave, displacement amplitude is 10−8 m, density of air is 1.3 Kg/m3, velocity in air is 340 m/s and frequency is 2000 Hz. The intensity of the wave will be given by
Answer» For a wave, displacement amplitude is $10^{- 8}$ m, density of air is 1.3 Kg/ $m^{3}$ , velocity in air is 340 m/s and frequency is 2000 Hz. The intensity of the wave will be given by

Discussion

10.	Two long parallel wires situated at a distance 2a are carrying equal current i in opposite direction as shown in figure. The value of magnetic field at a point P situated at equal distances from both the wires will be:
Answer» Two long parallel wires situated at a distance $2 a$ are carrying equal current $i$ in opposite direction as shown in figure. The value of magnetic field at a point $P$ situated at equal distances from both the wires will be:

Discussion

11.	A half ring of radius R is charged with a linear charged density λ. The field at the centre is
Answer» A half ring of radius R is charged with a linear charged density $λ$ . The field at the centre is

Discussion

12.	In the bottom of a vessel with mercury of density ρ there is a round hole of radius r. At what maximum height of the mercury layer will be liquid still not flow out through this hole? (surface tension - T)
Answer» In the bottom of a vessel with mercury of density $ρ$ there is a round hole of radius r. At what maximum height of the mercury layer will be liquid still not flow out through this hole? (surface tension - T)

Discussion

13.	40 wires each of resistance 1 Ω are arranged as shown in figure. A battery of emf 8 V and internal resistance 0.125 Ω is connected between A and B. Rate of heat loss from cage is 12×β W where β is an integer. Then the value of β is
Answer» $40$ wires each of resistance $1 Ω$ are arranged as shown in figure. A battery of $e m f$ $8 V$ and internal resistance $0.125 Ω$ is connected between $A$ and $B$ . Rate of heat loss from cage is $12 \times β W$ where $β$ is an integer. Then the value of $β$ is

Discussion

14.	Three blocks of masses 2 kg, 3 kg and 5 kg are connected to each other with light string and are then placed on a frictionless surface as shown in the figure. The system is pulled by a force F=10 N then tension T1=
Answer» Three blocks of masses 2 kg, 3 kg and 5 kg are connected to each other with light string and are then placed on a frictionless surface as shown in the figure. The system is pulled by a force F=10 N then tension T1=

14.

Three blocks of masses 2 kg, 3 kg and 5 kg are connected to each other with light string and are then placed on a frictionless surface as shown in the figure. The system is pulled by a force F=10 N then tension T1=

Answer»

Three blocks of masses 2 kg, 3 kg and 5 kg are connected to each other with light string and are then placed on a frictionless surface as shown in the figure. The system is pulled by a force F=10 N then tension T1=

Discussion

15.	A tuning fork vibrating with a sonometer in fundamental mode having a wire of length 20 cm produces 5 beats per second. The beat frequency does not change if the length of the wire is changed to 21 cm. The frequency of the tuning fork is
Answer» A tuning fork vibrating with a sonometer in fundamental mode having a wire of length $20 cm$ produces $5$ beats per second. The beat frequency does not change if the length of the wire is changed to $21 cm$ . The frequency of the tuning fork is

Discussion

16.	Surface tension of liquid is 70 dyne/cm. Its value in SI is
Answer» Surface tension of liquid is $70 dyne/cm$ . Its value in $SI$ is

Discussion

17.	A guitar wire A vibrates at a fundamental frequency 600 Hz. A second identical wire B (having fundamental frequency less than that of A) produces 6 beats per second with it when the tension in B is slightly decreased. Find the ratio of the tension in A to the tension in B.
Answer» A guitar wire $A$ vibrates at a fundamental frequency $600 Hz$ . A second identical wire $B$ (having fundamental frequency less than that of $A$ ) produces $6$ beats per second with it when the tension in $B$ is slightly decreased. Find the ratio of the tension in $A$ to the tension in $B$ .

Discussion

18.	A ball at rest is dropped into a well. The water is at a depth h from the surface. If the speed of sound is c, then the time after which the splash is heard will be
Answer» A ball at rest is dropped into a well. The water is at a depth $h$ from the surface. If the speed of sound is $c$ , then the time after which the splash is heard will be

Discussion

19.	A carnot engine operates between two reservoirs of temperature 900 K and 300 K. The engine performs 1200 J of work per cycle. The heat energy in (J) delivered by the engine to the low temperature reservoir, in a cycle, is
Answer» A carnot engine operates between two reservoirs of temperature 900 $K$ and 300 $K$ . The engine performs 1200 $J$ of work per cycle. The heat energy in ( $J$ ) delivered by the engine to the low temperature reservoir, in a cycle, is

Discussion

20.	A solid sphere of radius R, density ρ and specific heat s is initially at temperature T0 Kelvin. When suspended in a surrounding of temperature 0 K, the time required to decrease the temperature of the sphere from T0 to T02 Kelvin is (Assume that the sphere behaves like a black body)
Answer» A solid sphere of radius $R,$ density $ρ$ and specific heat $s$ is initially at temperature $T_{0}$ Kelvin. When suspended in a surrounding of temperature $0 K$ , the time required to decrease the temperature of the sphere from $T_{0}$ to $\frac{T_{0}}{2}$ Kelvin is (Assume that the sphere behaves like a black body)

Discussion

21.	The weather report reads, "Temperature 20^0 C : Relative humidity 100 %". What is the dew point ?
Answer» The weather report reads, "Temperature 20^0 C : Relative humidity 100 %". What is the dew point ?

Discussion

22.	A solid cylinder is kept on one edge of a plank of same mass and length 25 m placed on a smooth surface as shown in the figure. The coefficient of friction between the cylinder and the plank is 0.5. The plank is given an initial velocity of 20 m/s towards right. Find the time (in sec) after which plank and cylinder will separate.(g=10m/s2) 2
Answer» A solid cylinder is kept on one edge of a plank of same mass and length 25 m placed on a smooth surface as shown in the figure. The coefficient of friction between the cylinder and the plank is 0.5. The plank is given an initial velocity of 20 m/s towards right. Find the time (in sec) after which plank and cylinder will separate.( $g = 10 m / s^{2}$ ) 2

22.

A solid cylinder is kept on one edge of a plank of same mass and length 25 m placed on a smooth surface as shown in the figure. The coefficient of friction between the cylinder and the plank is 0.5. The plank is given an initial velocity of 20 m/s towards right. Find the time (in sec) after which plank and cylinder will separate.(g=10m/s2) 2

Answer»

A solid cylinder is kept on one edge of a plank of same mass and length 25 m placed on a smooth surface as shown in the figure. The coefficient of friction between the cylinder and the plank is 0.5. The plank is given an initial velocity of 20 m/s towards right. Find the time (in sec) after which plank and cylinder will separate.( $g = 10 m / s^{2}$ )

2

Discussion

23.	Starting from the centre of the earth having radius R, the variation of g (acceleration due to gravity) is shown by which of the following options
Answer» Starting from the centre of the earth having radius $R$ , the variation of $g$ (acceleration due to gravity) is shown by which of the following options

Discussion

24.	If there is no torsion in the suspension thread, then the time period of a magnet executing SHM is
Answer» If there is no torsion in the suspension thread, then the time period of a magnet executing SHM is

Discussion

25.	A simple microscope has a magnifying power of 3.0 when the image in formed at the near point (25 cm) of a normal eye. (a) What is its focal length? (b) What will be its magnifying power if the image is formed at infinity?
Answer» A simple microscope has a magnifying power of 3.0 when the image in formed at the near point (25 cm) of a normal eye. (a) What is its focal length? (b) What will be its magnifying power if the image is formed at infinity?

Discussion

26.	The half life of radioactive substance is 4 days. What is the probability of decay of a nucleus in 12 days?
Answer» The half life of radioactive substance is 4 days. What is the probability of decay of a nucleus in 12 days?

Discussion

27.	Total electric flux coming out of a unit positive charge put in air is
Answer» Total electric flux coming out of a unit positive charge put in air is

27.

Total electric flux coming out of a unit positive charge put in air is

Answer»

Total electric flux coming out of a unit positive charge put in air is

Discussion

28.	A girl sees through a circular glass slab(refractive index 1.50 of thickness 20 mm and diameter 60 cm to the bottom of a swimming pol. Refractive index of water is 1.33. The bottom surface of the slab is in contact with the water surface.The depth of swimming pool is 6m. The area of bottom of swimming pool that can be seen through the slab is approximately.
Answer» A girl sees through a circular glass slab(refractive index 1.50 of thickness 20 mm and diameter 60 cm to the bottom of a swimming pol. Refractive index of water is 1.33. The bottom surface of the slab is in contact with the water surface. The depth of swimming pool is 6m. The area of bottom of swimming pool that can be seen through the slab is approximately.

28.

A girl sees through a circular glass slab(refractive index 1.50 of thickness 20 mm and diameter 60 cm to the bottom of a swimming pol. Refractive index of water is 1.33. The bottom surface of the slab is in contact with the water surface.The depth of swimming pool is 6m. The area of bottom of swimming pool that can be seen through the slab is approximately.

Answer»

A girl sees through a circular glass slab(refractive index 1.50 of thickness 20 mm and diameter 60 cm to the bottom of a swimming pol. Refractive index of water is 1.33. The bottom surface of the slab is in contact with the water surface.

The depth of swimming pool is 6m. The area of bottom of swimming pool that can be seen through the slab is approximately.

Discussion

29.	A harmonic source (S) is driving a taut string. The other end of the string is tied to a wall that is not so rigid. It is observed that standing waves are formed in the string with ratio of amplitudes at the antinodes to that at the nodes equal to 8. What percentage of wave energy is transmitted to the wall?
Answer» A harmonic source $(S)$ is driving a taut string. The other end of the string is tied to a wall that is not so rigid. It is observed that standing waves are formed in the string with ratio of amplitudes at the antinodes to that at the nodes equal to $8$ . What percentage of wave energy is transmitted to the wall?

Discussion

30.	Two resistances R1=(3.0±0.1)Ω and R2=(6.0±0.2)Ω are to be joined together
Answer» Two resistances $R_{1} = (3.0 \pm 0.1) Ω$ and $R_{2} = (6.0 \pm 0.2) Ω$ are to be joined together

Discussion

31.	Two resistors of resistance 3Ω and 6Ω are in parallel and the combination is in series with a 4Ω resistor. A potential difference of 90V is applied across the network. The potential difference across 4Ω the resistor and the current in the 3Ω resistor are respectively,
Answer» Two resistors of resistance 3 $Ω$ and 6 $Ω$ are in parallel and the combination is in series with a 4 $Ω$ resistor. A potential difference of 90V is applied across the network. The potential difference across 4 $Ω$ the resistor and the current in the 3 $Ω$ resistor are respectively,

Discussion

32.	What is the difference between circular motion and rotational motion?
Answer» What is the difference between circular motion and rotational motion?

Discussion

33.	An adiabatic vessel of total volume V is divided into two equal parts by a conducting separator. The separator is fixed in this position. The part on the left contains one mole of an ideal gas (U= 1.5 nRT) and the part on the right contains two moles of the same gas. Initially, the i pressure on each side is p. The system is left for sufficient time so that a steady state is reached. Find (a) the work done by the gas in the left part during the process, (b) the temperature on the two sides in the beginning, (c) the final common temperature reached by the gases, (d) the heat given to the gas in the right part and (e) the increase in the internal energy of the gas in the left part.
Answer» An adiabatic vessel of total volume V is divided into two equal parts by a conducting separator. The separator is fixed in this position. The part on the left contains one mole of an ideal gas (U= 1.5 nRT) and the part on the right contains two moles of the same gas. Initially, the i pressure on each side is p. The system is left for sufficient time so that a steady state is reached. Find (a) the work done by the gas in the left part during the process, (b) the temperature on the two sides in the beginning, (c) the final common temperature reached by the gases, (d) the heat given to the gas in the right part and (e) the increase in the internal energy of the gas in the left part.

33.

An adiabatic vessel of total volume V is divided into two equal parts by a conducting separator. The separator is fixed in this position. The part on the left contains one mole of an ideal gas (U= 1.5 nRT) and the part on the right contains two moles of the same gas. Initially, the i pressure on each side is p. The system is left for sufficient time so that a steady state is reached. Find (a) the work done by the gas in the left part during the process, (b) the temperature on the two sides in the beginning, (c) the final common temperature reached by the gases, (d) the heat given to the gas in the right part and (e) the increase in the internal energy of the gas in the left part.

Answer»

An adiabatic vessel of total volume V is divided into two equal parts by a conducting separator. The separator is fixed in this position. The part on the left contains one mole of an ideal gas (U= 1.5 nRT) and the part on the right contains two moles of the same gas. Initially, the i pressure on each side is p. The system is left for sufficient time so that a steady state is reached. Find

(a) the work done by the gas in the left part during the process,

(b) the temperature on the two sides in the beginning,

(c) the final common temperature reached by the gases,

(d) the heat given to the gas in the right part and

(e) the increase in the internal energy of the gas in the left part.

Discussion

34.	The mutual inductance between two coils is 1.25 henry. If the current in the primary coil changes at a rate of 80 ampere/second, then the induced e.m.f. in the secondary coil is
Answer» The mutual inductance between two coils is 1.25 henry. If the current in the primary coil changes at a rate of 80 ampere/second, then the induced e.m.f. in the secondary coil is

Discussion

35.	Potential energy of a particle is given by U=(2−3x−4x2) J where 'x' is in 'm'. Find the magnitude of force at x=4 m, if the particle is free to move along x-direction.
Answer» Potential energy of a particle is given by $U = (2 - 3 x - 4 x^{2}) J$ where ' $x$ ' is in ' $m$ '. Find the magnitude of force at $x = 4 m$ , if the particle is free to move along $x$ -direction.

Discussion

36.	A cyclic process for 1 mole of an ideal gas is shown in the figure in the V−T diagram. The work done in AB,BC and CA respectively is
Answer» A cyclic process for 1 mole of an ideal gas is shown in the figure in the $V - T$ diagram. The work done in $A B, B C$ and $C A$ respectively is

Discussion

37.	Block B of mass 2 kg is placed on smooth horizontal plane. Block A of mass 1 kg is placed on block B. The coefficient of friction between A and B is 0.40. The block A is imparted a velocity 16 m/s at t = 0. Find the time at which momentum of the two blocks are equal (in seconds). (g=10 m/s2).
Answer» Block B of mass $2 kg$ is placed on smooth horizontal plane. Block A of mass $1 kg$ is placed on block B. The coefficient of friction between A and B is 0.40. The block A is imparted a velocity $16 m/s$ at t = 0. Find the time at which momentum of the two blocks are equal (in seconds). $(g = 10 {m/s}^{2})$ .

Discussion

38.	A box P and a coil Q are connected in series with an ac source of variable frequency. The emf of the source is constant at 10V. Box P contains a capacitance of 1 μF in series with a resistance of 32Ω. Coil Q has a self inductance of 4.9 mH and a resistance of 68Ω in series. The frequency is adjusted so that maximum current flows in P and Q. The voltage across P is
Answer» A box P and a coil Q are connected in series with an ac source of variable frequency. The emf of the source is constant at $10 V$ . Box P contains a capacitance of $1 μ F$ in series with a resistance of $32 Ω$ . Coil Q has a self inductance of 4.9 mH and a resistance of $68 Ω$ in series. The frequency is adjusted so that maximum current flows in P and Q. The voltage across P is

Discussion

39.	In the P-Vdiagram show, moles of a gas are taken through a process from state i to f, at constant pressure. Part of the heat must have gone into doing the work PΔV, and the rest in increasing the internal energy. If the molar specific heat at constant volume for the gas is CV, and the initial total internal energy is Ui, what is the final internal energy Uf?
Answer» In the P-Vdiagram show, moles of a gas are taken through a process from state i to f, at constant pressure. Part of the heat must have gone into doing the work $P Δ V$ , and the rest in increasing the internal energy. If the molar specific heat at constant volume for the gas is $C_{V}$ , and the initial total internal energy is $U_{i}$ , what is the final internal energy $U_{f}$ ?

39.

In the P-Vdiagram show, moles of a gas are taken through a process from state i to f, at constant pressure. Part of the heat must have gone into doing the work PΔV, and the rest in increasing the internal energy. If the molar specific heat at constant volume for the gas is CV, and the initial total internal energy is Ui, what is the final internal energy Uf?

Answer»

In the P-Vdiagram show, moles of a gas are taken through a process from state i to f, at constant pressure. Part of the heat must have gone into doing the work $P Δ V$ , and the rest in increasing the internal energy. If the molar specific heat at constant volume for the gas is $C_{V}$ , and the initial total internal energy is $U_{i}$ , what is the final internal energy $U_{f}$ ?

Discussion

40.	A radioactive nucleus can decay by two different processes with half-lives of 2 years and 4 years respectively. Effective half life of nucleus in years is (Write upto two digits after the decimal point)
Answer» A radioactive nucleus can decay by two different processes with half-lives of 2 years and 4 years respectively. Effective half life of nucleus in years is (Write upto two digits after the decimal point)

Discussion

41.	When a small sphere moves at low speed through a fluid, the viscous force F, opposing the motion is experimentally found to depend upon the radius r, the velocity v of the sphere and the viscosity η of the fluid. Expression of force is proportional toNote: [η]=[ML−1T−1]
Answer» When a small sphere moves at low speed through a fluid, the viscous force $F$ , opposing the motion is experimentally found to depend upon the radius $r$ , the velocity $v$ of the sphere and the viscosity $η$ of the fluid. Expression of force is proportional to Note: $[η] = [M L^{- 1} T^{- 1}]$

Discussion

42.	A boat, which has a speed of 5 km/h in still water, crosses a river of width 1 km along the shortest possible path in 15 minutes. The velocity of the river water in kilometers per hour is
Answer» A boat, which has a speed of $5 km/h$ in still water, crosses a river of width $1 km$ along the shortest possible path in $15$ minutes. The velocity of the river water in kilometers per hour is

Discussion

43.	A position dependent force F is acting on a particle and its force position curve is shown in the figure. Change in kinetic energy of the particle, when its displacement is from 0 to 5 m is
Answer» A position dependent force $F$ is acting on a particle and its force position curve is shown in the figure. Change in kinetic energy of the particle, when its displacement is from $0$ to $5 m$ is

Discussion

44.	Find the minimum value of 'm', for the sytem to be in equilibrium. Take g=10 m/s2.
Answer» Find the minimum value of ' $m$ ', for the sytem to be in equilibrium. Take $g = 10 m / s^{2}$ .

Discussion

45.	In the figure, the block B begins to rise when the frame rotates at 38.2 rpm. Find the coefficient of friction under block A, if coefficient of friction between block B and wall is 0.2(Assume g=10m/s2).
Answer» In the figure, the block B begins to rise when the frame rotates at $38.2 rpm$ . Find the coefficient of friction under block A, if coefficient of friction between block B and wall is $0.2$ (Assume $g = 10 {m/s}^{2}$ ).

Discussion

46.	Why is change in potential negative of the work done by conservative forces
Answer» Why is change in potential negative of the work done by conservative forces

Discussion

47.	In the diagram shown, Q iaf=80 cal and W iaf=50 cal. If W=−30 cal for the curved path along fi, value of Q for path fi, will be
Answer» In the diagram shown, $Q_{i a f} = 80 cal$ and $W_{i a f} = 50 cal$ . If $W = - 30 cal$ for the curved path along $f i$ , value of $Q$ for path $f i$ , will be

Discussion

48.	The flux passing through the surface S5 will be
Answer» The flux passing through the surface $S_{5}$ will be

Discussion

49.	A small ball 'A' of mass 'm' is attached rigidly to the end of a light rod of length 'd'. The structure rotates with about an axis perpendicular to the rod and passing through its other end with an angular velocity 'ω'. Calculate the angular momentum of the system about this axis?
Answer» A small ball 'A' of mass 'm' is attached rigidly to the end of a light rod of length 'd'. The structure rotates with about an axis perpendicular to the rod and passing through its other end with an angular velocity ' $ω$ '. Calculate the angular momentum of the system about this axis?

Discussion

50.	A steamer moves with a velocity 3 kmph in and against the direction of river water whose velocity is 2 kmph. Total time for total journey if the boat travels 2 km in direction of stream and then back to its place will be (in hour)
Answer» A steamer moves with a velocity 3 kmph in and against the direction of river water whose velocity is 2 kmph. Total time for total journey if the boat travels 2 km in direction of stream and then back to its place will be (in hour)

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A proton and an α - particle enter a uniform magnetic field perpendicularly with same speed. If proton takes 25 μs to make 5 revolutions, then the time period of the α - particle would be equal to

Three capacitors each having capacitance C=2 μF are connected with a battery of e.m.f. 30 V as shown in the figure. When the switch S is closed, the extra amount of charge flown through the battery is

Wavelength of light of frequency 100 Hz is,

Two mirrors are inclined at an angle 60∘. If an object is placed symmetrically between them, then the number of images formed will be

A particle moves according to the law x = a cos πt2. The distance covered by it in the time interval between t = 0 to t = 3 s is

For a wave, displacement amplitude is 10−8 m, density of air is 1.3 Kg/m3, velocity in air is 340 m/s and frequency is 2000 Hz. The intensity of the wave will be given by

Two long parallel wires situated at a distance 2a are carrying equal current i in opposite direction as shown in figure. The value of magnetic field at a point P situated at equal distances from both the wires will be:

A half ring of radius R is charged with a linear charged density λ. The field at the centre is

In the bottom of a vessel with mercury of density ρ there is a round hole of radius r. At what maximum height of the mercury layer will be liquid still not flow out through this hole? (surface tension - T)

40 wires each of resistance 1 Ω are arranged as shown in figure. A battery of emf 8 V and internal resistance 0.125 Ω is connected between A and B. Rate of heat loss from cage is 12×β W where β is an integer. Then the value of β is

Three blocks of masses 2 kg, 3 kg and 5 kg are connected to each other with light string and are then placed on a frictionless surface as shown in the figure. The system is pulled by a force F=10 N then tension T1=

A tuning fork vibrating with a sonometer in fundamental mode having a wire of length 20 cm produces 5 beats per second. The beat frequency does not change if the length of the wire is changed to 21 cm. The frequency of the tuning fork is

Surface tension of liquid is 70 dyne/cm. Its value in SI is

A guitar wire A vibrates at a fundamental frequency 600 Hz. A second identical wire B (having fundamental frequency less than that of A) produces 6 beats per second with it when the tension in B is slightly decreased. Find the ratio of the tension in A to the tension in B.

A ball at rest is dropped into a well. The water is at a depth h from the surface. If the speed of sound is c, then the time after which the splash is heard will be

A carnot engine operates between two reservoirs of temperature 900 K and 300 K. The engine performs 1200 J of work per cycle. The heat energy in (J) delivered by the engine to the low temperature reservoir, in a cycle, is

A solid sphere of radius R, density ρ and specific heat s is initially at temperature T0 Kelvin. When suspended in a surrounding of temperature 0 K, the time required to decrease the temperature of the sphere from T0 to T02 Kelvin is (Assume that the sphere behaves like a black body)

The weather report reads, "Temperature 20^0 C : Relative humidity 100 %". What is the dew point ?

Starting from the centre of the earth having radius R, the variation of g (acceleration due to gravity) is shown by which of the following options

If there is no torsion in the suspension thread, then the time period of a magnet executing SHM is

A simple microscope has a magnifying power of 3.0 when the image in formed at the near point (25 cm) of a normal eye. (a) What is its focal length? (b) What will be its magnifying power if the image is formed at infinity?

The half life of radioactive substance is 4 days. What is the probability of decay of a nucleus in 12 days?

Total electric flux coming out of a unit positive charge put in air is

Two resistances R1=(3.0±0.1)Ω and R2=(6.0±0.2)Ω are to be joined together

Two resistors of resistance 3Ω and 6Ω are in parallel and the combination is in series with a 4Ω resistor. A potential difference of 90V is applied across the network. The potential difference across 4Ω the resistor and the current in the 3Ω resistor are respectively,

What is the difference between circular motion and rotational motion?

The mutual inductance between two coils is 1.25 henry. If the current in the primary coil changes at a rate of 80 ampere/second, then the induced e.m.f. in the secondary coil is

Potential energy of a particle is given by U=(2−3x−4x2) J where 'x' is in 'm'. Find the magnitude of force at x=4 m, if the particle is free to move along x-direction.

A cyclic process for 1 mole of an ideal gas is shown in the figure in the V−T diagram. The work done in AB,BC and CA respectively is

Block B of mass 2 kg is placed on smooth horizontal plane. Block A of mass 1 kg is placed on block B. The coefficient of friction between A and B is 0.40. The block A is imparted a velocity 16 m/s at t = 0. Find the time at which momentum of the two blocks are equal (in seconds). (g=10 m/s2).

A radioactive nucleus can decay by two different processes with half-lives of 2 years and 4 years respectively. Effective half life of nucleus in years is (Write upto two digits after the decimal point)

When a small sphere moves at low speed through a fluid, the viscous force F, opposing the motion is experimentally found to depend upon the radius r, the velocity v of the sphere and the viscosity η of the fluid. Expression of force is proportional toNote: [η]=[ML−1T−1]

A boat, which has a speed of 5 km/h in still water, crosses a river of width 1 km along the shortest possible path in 15 minutes. The velocity of the river water in kilometers per hour is

A position dependent force F is acting on a particle and its force position curve is shown in the figure. Change in kinetic energy of the particle, when its displacement is from 0 to 5 m is

Find the minimum value of 'm', for the sytem to be in equilibrium. Take g=10 m/s2.

In the figure, the block B begins to rise when the frame rotates at 38.2 rpm. Find the coefficient of friction under block A, if coefficient of friction between block B and wall is 0.2(Assume g=10m/s2).

Why is change in potential negative of the work done by conservative forces

In the diagram shown, Q iaf=80 cal and W iaf=50 cal. If W=−30 cal for the curved path along fi, value of Q for path fi, will be

The flux passing through the surface S5 will be

A small ball 'A' of mass 'm' is attached rigidly to the end of a light rod of length 'd'. The structure rotates with about an axis perpendicular to the rod and passing through its other end with an angular velocity 'ω'. Calculate the angular momentum of the system about this axis?

A steamer moves with a velocity 3 kmph in and against the direction of river water whose velocity is 2 kmph. Total time for total journey if the boat travels 2 km in direction of stream and then back to its place will be (in hour)