50278 + Interview Questions in Physics

1.	A 10 kg stone is suspended with a rope of breaking strength 30 kg-wt. The minimum time in which the stone can be raised through a height 10 m starting from rest is (taking g=10 N/kg)
Answer» A $10 kg$ stone is suspended with a rope of breaking strength $30 kg-wt$ . The minimum time in which the stone can be raised through a height $10 m$ starting from rest is (taking $g = 10 N/kg$ )

Discussion

2.	Find the Requivalent.
Answer» Find the $R_{e q u i v a l e n t}$ .

Discussion

3.	The moment of inertia of a system of four rods, each of length 'l' and mass 'm', about the axis shown is
Answer» The moment of inertia of a system of four rods, each of length 'l' and mass 'm', about the axis shown is

3.

The moment of inertia of a system of four rods, each of length 'l' and mass 'm', about the axis shown is

Answer»

The moment of inertia of a system of four rods, each of length 'l' and mass 'm', about the axis shown is

Discussion

4.	A bullet passes past a person at a speed 220 ms−1. Find the fractional change in the frequency of the whistling sound heard by the person as the bullet crosses the person. Speed of sound =330 ms−1.
Answer» A bullet passes past a person at a speed $220 {ms}^{- 1}$ . Find the fractional change in the frequency of the whistling sound heard by the person as the bullet crosses the person. Speed of sound $= 330 {ms}^{- 1}$ .

Discussion

5.	The following fig. shows I-V graph for a given metallic wire at two temperatures T1 and T2.Then,
Answer» The following fig. shows I-V graph for a given metallic wire at two temperatures T₁ and T₂.Then,

Discussion

6.	The projection of vector →b+→c on →a is _____ Where →a=2^i−3^j+4^k→b=3^i−3^j+3^k→c=^i+^j+3^k
Answer» The projection of vector $\to b + \to c$ on $\to a$ is _____ Where $\to a = 2^i - 3^j + 4^k \to b = 3^i - 3^j + 3^k \to c =^i +^j + 3^k$

Discussion

7.	Derivation ofProduction of Amplitude modulated wave
Answer» Derivation ofProduction of Amplitude modulated wave

Discussion

8.	Solution A has ΨS=–30 bars and ΨP=5 bars. Solution B has ΨS=–10 bar and ΨP=0 atm. The two are separated by semipermeable membrane. Flow of water will be
Answer» Solution A has $Ψ_{S} = - 30$ bars and $Ψ_{P} = 5$ bars. Solution B has $Ψ_{S} = - 10$ bar and $Ψ_{P} = 0$ atm. The two are separated by semipermeable membrane. Flow of water will be

Discussion

9.	A river 5√3 km wide flows with a velocity of 5 kmph. A boat which can move with a velocity of 10 kmph in still water crosses the river, without any drift. For this, the boat has to tilt its velocity by θ with the straight path in the right direction (see figiure). If the boat's velocity is tilted by the same angle θ in the wrong direction, the drift will be
Answer» A river $5 \sqrt{3} k m$ wide flows with a velocity of $5 k m p h$ . A boat which can move with a velocity of $10 k m p h$ in still water crosses the river, without any drift. For this, the boat has to tilt its velocity by $θ$ with the straight path in the right direction (see figiure). If the boat's velocity is tilted by the same angle $θ$ in the wrong direction, the drift will be

Discussion

10.	A myopic person can not see objects lying beyond 2 m. The focal length and power of the lens required to remove this defect will be
Answer» A myopic person can not see objects lying beyond $2 m$ . The focal length and power of the lens required to remove this defect will be

Discussion

11.	An un deformed spring of spring constant k is connected to a bead of mass m as shown in figure.Bead can move along long rigid rod without friction. A particle of mass m moving with velocity v in the vertical plane containing spring and rod strikes bead at an angle 450 with horizontal and sticks to bead. Choose correct alternative representing maximum elongation of spring is, all particles are in same horizontal plane.
Answer» An un deformed spring of spring constant k is connected to a bead of mass m as shown in figure.Bead can move along long rigid rod without friction. A particle of mass m moving with velocity v in the vertical plane containing spring and rod strikes bead at an angle $45^{0}$ with horizontal and sticks to bead. Choose correct alternative representing maximum elongation of spring is, all particles are in same horizontal plane.

11.

An un deformed spring of spring constant k is connected to a bead of mass m as shown in figure.Bead can move along long rigid rod without friction. A particle of mass m moving with velocity v in the vertical plane containing spring and rod strikes bead at an angle 450 with horizontal and sticks to bead. Choose correct alternative representing maximum elongation of spring is, all particles are in same horizontal plane.

Answer»

An un deformed spring of spring constant k is connected to a bead of mass m as shown in figure.Bead can move along long rigid rod without friction. A particle of mass m moving with velocity v in the vertical plane containing spring and rod strikes bead at an angle $45^{0}$ with horizontal and sticks to bead. Choose correct alternative representing maximum elongation of spring is, all particles are in same horizontal plane.

Discussion

12.	A body of mass 10 kg is slipping on a rough horizontal plane and moves with a deceleration of 4.0 m/ s2. What is the magnitude of frictional force?
Answer» A body of mass 10 kg is slipping on a rough horizontal plane and moves with a deceleration of 4.0 m/ $s^{2}$ . What is the magnitude of frictional force?

Discussion

13.	One end of a copper rod of uniform cross section and length 1.5 m is in contact with ice and the other end with steam at 100∘C. At what point along its length from A should a temperature of 200∘C be maintained so that in steady state, the mass of the ice melting is equal to that of steam produced in the same interval of time . [Lv=540 cal/g,Lf=80 cal/ g]
Answer» One end of a copper rod of uniform cross section and length $1.5 m$ is in contact with ice and the other end with steam at $100^{\circ} C$ . At what point along its length from $A$ should a temperature of $200^{\circ} C$ be maintained so that in steady state, the mass of the ice melting is equal to that of steam produced in the same interval of time . $[L_{v} = 540 cal/g, L_{f} = 80 cal/ g]$

Discussion

14.	In the previous problem, suppose m2=2.0kg and m3=3.0kg. What should be the mass m so that it remains at rest ?
Answer» In the previous problem, suppose $m_{2} = 2.0$ kg and $m_{3} = 3.0 k g$ . What should be the mass m so that it remains at rest ?

Discussion

15.	A closed organ pipe has length l. The air in it is vibrating in 3rd overtone with maximum amplitude A. The amplitude at a distance of l7 from closed end of the pipe is equal to xA where x is
Answer» A closed organ pipe has length $l$ . The air in it is vibrating in $3^{r d}$ overtone with maximum amplitude $A$ . The amplitude at a distance of $\frac{l}{7}$ from closed end of the pipe is equal to $x A$ where x is

Discussion

16.	Three liquids having densities ρ1, ρ2 and ρ 3 ( ρ1>ρ2>ρ3), having the same value of surface tension T, rise to the same height h in three identical capillaries. The angle of contact θ1, θ2 and θ3 obeys
Answer» Three liquids having densities $ρ_{1}, ρ_{2}$ and $ρ_{3}$ $(ρ_{1} > ρ_{2} > ρ_{3})$ , having the same value of surface tension $T$ , rise to the same height $h$ in three identical capillaries. The angle of contact $θ_{1}, θ_{2}$ and $θ_{3}$ obeys

Discussion

17.	A satellite of earth is moving in a circular orbit. It is observed that at point B which is nearest to earth weight of astronaut of mass m is zero and at point A weight of astronaut is found to be n(mgDR) where D is width of satellite, R is radius of circular orbit and g is acceleration due to gravity at satellite. If R>>D, then n is
Answer» A satellite of earth is moving in a circular orbit. It is observed that at point B which is nearest to earth weight of astronaut of mass m is zero and at point A weight of astronaut is found to be $n (\frac{m g D}{R})$ where D is width of satellite, R is radius of circular orbit and g is acceleration due to gravity at satellite. If R>>D, then n is

Discussion

18.	The resultant force of 5 N and 10 N cannot be
Answer» The resultant force of $5 N$ and $10 N$ cannot be

Discussion

19.	When monochromatic light of intensity I and frequency v=3v0( v0 is the threshold frequency) is incident on the cathode in a photoelectric experiment setup the saturation current is found to be 2μA and the stopping potential is V0. The photoelectric efficiency of the photo metal used to coat the cathode is independent of the frequency of incident radiation. If the Intensity of the incident radiation is doubled and its frequency halved then choose the correct statement(s).
Answer» When monochromatic light of intensity I and frequency $v = 3 v_{0}$ ( $v_{0}$ is the threshold frequency) is incident on the cathode in a photoelectric experiment setup the saturation current is found to be $2 μ A$ and the stopping potential is $V_{0}$ . The photoelectric efficiency of the photo metal used to coat the cathode is independent of the frequency of incident radiation. If the Intensity of the incident radiation is doubled and its frequency halved then choose the correct statement(s).

Discussion

20.	The block m1 is loaded on the block m2. If there is no relative sliding between the blocks and the inclined plane is smooth, find the friction force between the blocks.
Answer» The block $m_{1}$ is loaded on the block $m_{2}$ . If there is no relative sliding between the blocks and the inclined plane is smooth, find the friction force between the blocks.

20.

The block m1 is loaded on the block m2. If there is no relative sliding between the blocks and the inclined plane is smooth, find the friction force between the blocks.

Answer»

The block $m_{1}$ is loaded on the block $m_{2}$ . If there is no relative sliding between the blocks and the inclined plane is smooth, find the friction force between the blocks.

Discussion

21.	A small bob is connected to one end of two identical massless strings each of length 12 cm. The other ends of the strings are fixed to a vertical rod as shown in the figure. If the tension in the first string T1 is 2 times that of the tension in the second string T2, then what will be the angular velocity of the bob?
Answer» A small bob is connected to one end of two identical massless strings each of length $12 cm$ . The other ends of the strings are fixed to a vertical rod as shown in the figure. If the tension in the first string $T_{1}$ is 2 times that of the tension in the second string $T_{2}$ , then what will be the angular velocity of the bob?

Discussion

22.	A parallel plate capacitor is made by stacking n equally spaced plates connected alternatively. If the capacitance between any two adjacent plates is C, then the resultant capacitance is
Answer» A parallel plate capacitor is made by stacking $n$ equally spaced plates connected alternatively. If the capacitance between any two adjacent plates is $C$ , then the resultant capacitance is

Discussion

23.	Find the scalar and vector components of the vector with initial point (2,1) and terminal point (-5, 7).
Answer» Find the scalar and vector components of the vector with initial point (2,1) and terminal point (-5, 7).

Discussion

24.	Can a telescope be constructed using two concave lenses? If not, why? And if it is possible, how does it work?
Answer» Can a telescope be constructed using two concave lenses? If not, why? And if it is possible, how does it work?

Discussion

25.	A point charge Q is placed at the origin. Find the electrostatic energy stored outside the sphere of radius R centred at the origin.
Answer» A point charge Q is placed at the origin. Find the electrostatic energy stored outside the sphere of radius R centred at the origin.

Discussion

26.	A heavy particle is suspended by a string of length l. The particle is given a horizontal velocity v0. The string becomes slack at some angle and the particle proceeds on a parabola. Find the value of v0 if the particle passes through the point of suspension.
Answer» A heavy particle is suspended by a string of length l. The particle is given a horizontal velocity $v_{0}$ . The string becomes slack at some angle and the particle proceeds on a parabola. Find the value of $v_{0}$ if the particle passes through the point of suspension.

Discussion

27.	Why is the inductor always a solenoid?
Answer» Why is the inductor always a solenoid?

Discussion

28.	Sir if we take magnitude of charges in proving the potential energy it come negative but why it is not so in case of kinetic energy ??? I know so kinetic energy can never be negative so please help me to make a clear intuition in my mind.....
Answer» Sir if we take magnitude of charges in proving the potential energy it come negative but why it is not so in case of kinetic energy ??? I know so kinetic energy can never be negative so please help me to make a clear intuition in my mind.....

Discussion

29.	An ice cube is floating in a beaker filled with water .when ice melts ,the water level will?
Answer» An ice cube is floating in a beaker filled with water .when ice melts ,the water level will?

Discussion

30.	A car is moving on a smooth horizontal road. Find the ratio of work done by the engine of the car, in order to change its speed from 0 to v and v to 2v.
Answer» A car is moving on a smooth horizontal road. Find the ratio of work done by the engine of the car, in order to change its speed from $0$ to $v$ and $v$ to $2 v$ .

Discussion

31.	consider the charges q q and -q placed at the vertices of an equilateral triangle,as shown. What is the force on each charge?this is the example sum 1.7 from ncert textbook
Answer» consider the charges q q and -q placed at the vertices of an equilateral triangle,as shown. What is the force on each charge?this is the example sum 1.7 from ncert textbook

Discussion

32.	An impulse is applied on a rod at a distance 'y' away from centre C as shown in figure. Rod is kept on frictionless horizontal surface. For what 'y' velocity of end A is zero just after impact?
Answer» An impulse is applied on a rod at a distance 'y' away from centre C as shown in figure. Rod is kept on frictionless horizontal surface. For what 'y' velocity of end A is zero just after impact?

Discussion

33.	Consider two hot bodies B1 and B2 which have temperatures 100∘C and 80∘C, respectively at t=0. The temperature of the surroundings is 40∘C. The ratio of the respective rates of cooling R1 and R2 of these two bodies at t=0 will be
Answer» Consider two hot bodies $B_{1}$ and $B_{2}$ which have temperatures $100^{\circ} C$ and $80^{\circ} C$ , respectively at $t = 0$ . The temperature of the surroundings is $40^{\circ} C$ . The ratio of the respective rates of cooling $R_{1}$ and $R_{2}$ of these two bodies at $t = 0$ will be

Discussion

34.	Find the force exerted at the support S in terms of ‘m’ if the system shown is in equilibrium.
Answer» Find the force exerted at the support $S$ in terms of ‘ $m$ ’ if the system shown is in equilibrium.

Discussion

35.	The initial pressure & volume of a given mass of gas with CPCV=75 are 2 atm & 4.8 m3. The gas can exchange heat with the surroundings. It is suddenly compressed to 1.2 m3 and then slowly compressed to 0.6 m3. Find the final pressure of the gas.
Answer» The initial pressure & volume of a given mass of gas with $\frac{C_{P}}{C_{V}} = \frac{7}{5}$ are $2 atm$ & $4.8 m^{3}$ . The gas can exchange heat with the surroundings. It is suddenly compressed to $1.2 m^{3}$ and then slowly compressed to $0.6 m^{3}$ . Find the final pressure of the gas.

Discussion

36.	A uniform chain of mass m and length l overhangs a table with its two third part on the table.Find the work to be done, by a person to put the hanging part back on the table.
Answer» A uniform chain of mass m and length l overhangs a table with its two third part on the table.Find the work to be done, by a person to put the hanging part back on the table.

Discussion

37.	A particle starts from rest and moves with a constant acceleration of 10 ms−2 . Then the displacement in first 5 sec of the motion will be
Answer» A particle starts from rest and moves with a constant acceleration of $10 {ms}^{- 2}$ . Then the displacement in first $5 sec$ of the motion will be

Discussion

38.	Find the ratio of specific gas constant for H2 to the specific gas constant for O2?
Answer» Find the ratio of specific gas constant for $H_{2}$ to the specific gas constant for $O_{2}$ ?

Discussion

39.	Classify the given measure as scalar and vector: (i) 40 W
Answer» Classify the given measure as scalar and vector: (i) 40 W

Discussion

40.	A particle is given an initial speed u inside a smooth spherical shell of radius R=1 m, so that it is just able to complete the circle. Acceleration of the particle when its velocity is vertical, is
Answer» A particle is given an initial speed $u$ inside a smooth spherical shell of radius $R = 1 m$ , so that it is just able to complete the circle. Acceleration of the particle when its velocity is vertical, is

Discussion

41.	A car traveling at a speed of 20m/s due north along the way makes a right turn on to a side road that heads to east. It takes 50 sec for the car to complete the turn. At the end of the 50s, the car has the speed of 15m/s along the side road. Determine the magnitude of average acceleration over the 50s interval.
Answer» A car traveling at a speed of 20m/s due north along the way makes a right turn on to a side road that heads to east. It takes 50 sec for the car to complete the turn. At the end of the 50s, the car has the speed of 15m/s along the side road. Determine the magnitude of average acceleration over the 50s interval.

Discussion

42.	Magnetic flux density, magnetising field, magnetic permeability, magnetic susceptibility, intensity of magnetisation are VECTOR or SCALAR quantity?
Answer» Magnetic flux density, magnetising field, magnetic permeability, magnetic susceptibility, intensity of magnetisation are VECTOR or SCALAR quantity?

Discussion

43.	Two spheres made of the same material have the same diameter. One sphere is hollow and the other is solid. If they are heated through the same range of temperature,
Answer» Two spheres made of the same material have the same diameter. One sphere is hollow and the other is solid. If they are heated through the same range of temperature,

Discussion

44.	If K is the Boltzmann constant, the average kinetic energy of a gas molecule at absolute Temperature T is
Answer» If $K$ is the Boltzmann constant, the average kinetic energy of a gas molecule at absolute Temperature $T$ is

Discussion

45.	Explain what is meant by scalar product and vector product.
Answer» Explain what is meant by scalar product and vector product.

Discussion

46.	A ball of mass m is dropped onto a floor from a certain height.The collision is perfectly elastic and the ball rebounds to the same height and again falls.Find the average force exerted by the ball on the floor during a long time interval.
Answer» A ball of mass m is dropped onto a floor from a certain height.The collision is perfectly elastic and the ball rebounds to the same height and again falls.Find the average force exerted by the ball on the floor during a long time interval.

Discussion

47.	What is a vector quantity?
Answer» What is a vector quantity?

Discussion

48.	An increase in intensity level of 1 dB implies an increase in intensity of (given anti log100.1=1.2589)
Answer» An increase in intensity level of 1 dB implies an increase in intensity of (given anti $l o g_{10} 0.1 = 1.2589)$

Discussion

49.	A rubber ball of mass 50 g falls from a height of 5 m and rebounds to a height of 1.25 m. Find the impulse and the average force between the ball and the ground if the time for which they are in contact .
Answer» A rubber ball of mass 50 g falls from a height of 5 m and rebounds to a height of 1.25 m. Find the impulse and the average force between the ball and the ground if the time for which they are in contact .

Discussion

50.	Find the value of R in the given figure so that there is no current in the 10Ω resistor.
Answer» Find the value of R in the given figure so that there is no current in the $10 Ω$ resistor.

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A 10 kg stone is suspended with a rope of breaking strength 30 kg-wt. The minimum time in which the stone can be raised through a height 10 m starting from rest is (taking g=10 N/kg)

Find the Requivalent.

The moment of inertia of a system of four rods, each of length 'l' and mass 'm', about the axis shown is

A bullet passes past a person at a speed 220 ms−1. Find the fractional change in the frequency of the whistling sound heard by the person as the bullet crosses the person. Speed of sound =330 ms−1.

The following fig. shows I-V graph for a given metallic wire at two temperatures T1 and T2.Then,

The projection of vector →b+→c on →a is _____ Where →a=2^i−3^j+4^k→b=3^i−3^j+3^k→c=^i+^j+3^k

Derivation ofProduction of Amplitude modulated wave

Solution A has ΨS=–30 bars and ΨP=5 bars. Solution B has ΨS=–10 bar and ΨP=0 atm. The two are separated by semipermeable membrane. Flow of water will be

A myopic person can not see objects lying beyond 2 m. The focal length and power of the lens required to remove this defect will be

A body of mass 10 kg is slipping on a rough horizontal plane and moves with a deceleration of 4.0 m/ s2. What is the magnitude of frictional force?

In the previous problem, suppose m2=2.0kg and m3=3.0kg. What should be the mass m so that it remains at rest ?

A closed organ pipe has length l. The air in it is vibrating in 3rd overtone with maximum amplitude A. The amplitude at a distance of l7 from closed end of the pipe is equal to xA where x is

Three liquids having densities ρ1, ρ2 and ρ 3 ( ρ1&gt;ρ2&gt;ρ3), having the same value of surface tension T, rise to the same height h in three identical capillaries. The angle of contact θ1, θ2 and θ3 obeys

The resultant force of 5 N and 10 N cannot be

The block m1 is loaded on the block m2. If there is no relative sliding between the blocks and the inclined plane is smooth, find the friction force between the blocks.

A parallel plate capacitor is made by stacking n equally spaced plates connected alternatively. If the capacitance between any two adjacent plates is C, then the resultant capacitance is

Find the scalar and vector components of the vector with initial point (2,1) and terminal point (-5, 7).

Can a telescope be constructed using two concave lenses? If not, why? And if it is possible, how does it work?

A point charge Q is placed at the origin. Find the electrostatic energy stored outside the sphere of radius R centred at the origin.

A heavy particle is suspended by a string of length l. The particle is given a horizontal velocity v0. The string becomes slack at some angle and the particle proceeds on a parabola. Find the value of v0 if the particle passes through the point of suspension.

Why is the inductor always a solenoid?

Sir if we take magnitude of charges in proving the potential energy it come negative but why it is not so in case of kinetic energy ??? I know so kinetic energy can never be negative so please help me to make a clear intuition in my mind.....

An ice cube is floating in a beaker filled with water .when ice melts ,the water level will?

A car is moving on a smooth horizontal road. Find the ratio of work done by the engine of the car, in order to change its speed from 0 to v and v to 2v.

consider the charges q q and -q placed at the vertices of an equilateral triangle,as shown. What is the force on each charge?this is the example sum 1.7 from ncert textbook

An impulse is applied on a rod at a distance 'y' away from centre C as shown in figure. Rod is kept on frictionless horizontal surface. For what 'y' velocity of end A is zero just after impact?

Consider two hot bodies B1 and B2 which have temperatures 100∘C and 80∘C, respectively at t=0. The temperature of the surroundings is 40∘C. The ratio of the respective rates of cooling R1 and R2 of these two bodies at t=0 will be

Find the force exerted at the support S in terms of ‘m’ if the system shown is in equilibrium.

The initial pressure &amp; volume of a given mass of gas with CPCV=75 are 2 atm &amp; 4.8 m3. The gas can exchange heat with the surroundings. It is suddenly compressed to 1.2 m3 and then slowly compressed to 0.6 m3. Find the final pressure of the gas.

A uniform chain of mass m and length l overhangs a table with its two third part on the table.Find the work to be done, by a person to put the hanging part back on the table.

A particle starts from rest and moves with a constant acceleration of 10 ms−2 . Then the displacement in first 5 sec of the motion will be

Find the ratio of specific gas constant for H2 to the specific gas constant for O2?

Classify the given measure as scalar and vector: (i) 40 W

A particle is given an initial speed u inside a smooth spherical shell of radius R=1 m, so that it is just able to complete the circle. Acceleration of the particle when its velocity is vertical, is

Magnetic flux density, magnetising field, magnetic permeability, magnetic susceptibility, intensity of magnetisation are VECTOR or SCALAR quantity?

Two spheres made of the same material have the same diameter. One sphere is hollow and the other is solid. If they are heated through the same range of temperature,

If K is the Boltzmann constant, the average kinetic energy of a gas molecule at absolute Temperature T is

Explain what is meant by scalar product and vector product.

A ball of mass m is dropped onto a floor from a certain height.The collision is perfectly elastic and the ball rebounds to the same height and again falls.Find the average force exerted by the ball on the floor during a long time interval.

What is a vector quantity?

An increase in intensity level of 1 dB implies an increase in intensity of (given anti log100.1=1.2589)

A rubber ball of mass 50 g falls from a height of 5 m and rebounds to a height of 1.25 m. Find the impulse and the average force between the ball and the ground if the time for which they are in contact .

Find the value of R in the given figure so that there is no current in the 10Ω resistor.

Three liquids having densities ρ1, ρ2 and ρ 3 ( ρ1>ρ2>ρ3), having the same value of surface tension T, rise to the same height h in three identical capillaries. The angle of contact θ1, θ2 and θ3 obeys

The initial pressure & volume of a given mass of gas with CPCV=75 are 2 atm & 4.8 m3. The gas can exchange heat with the surroundings. It is suddenly compressed to 1.2 m3 and then slowly compressed to 0.6 m3. Find the final pressure of the gas.