50278 + Interview Questions in Physics

1.	A wave yi = 0.3 cos (40t − 0.2x) is travelling along a string toward a boundary at x = 0. What are the expressions for the reflected waves if the string has a fixed end and at x = 0. Assume SI units.
Answer» A wave $y_{i} = 0.3 c o s (40 t - 0.2 x)$ is travelling along a string toward a boundary at $x = 0$ . What are the expressions for the reflected waves if the string has a fixed end and at $x = 0$ . Assume SI units.

Discussion

2.	Figure shows a loop-the-loop track of radius R. A car (without engine) starts from a platform at a distance h above the top of the loop and goes around the loop without falling off the track. Find the minimum value of h for a successful looping. Neglect friction.
Answer» Figure shows a loop-the-loop track of radius R. A car (without engine) starts from a platform at a distance h above the top of the loop and goes around the loop without falling off the track. Find the minimum value of h for a successful looping. Neglect friction.

2.

Figure shows a loop-the-loop track of radius R. A car (without engine) starts from a platform at a distance h above the top of the loop and goes around the loop without falling off the track. Find the minimum value of h for a successful looping. Neglect friction.

Answer»

Figure shows a loop-the-loop track of radius R. A car (without engine) starts from a platform at a distance h above the top of the loop and goes around the loop without falling off the track. Find the minimum value of h for a successful looping. Neglect friction.

Discussion

3.	The bob of a pendulum of length, I is pulled aside from its equilibrium position through an angle θ and then released. what will be the speed V of the bob when it pass through its equilibrium condition.
Answer» The bob of a pendulum of length, I is pulled aside from its equilibrium position through an angle θ and then released. what will be the speed V of the bob when it pass through its equilibrium condition.

Discussion

4.	An external pressure P is applied on a cube at 0oC so that it is equally compressed from all sides. K is the bulk modulus of the material of the cube and α is its coefficient of linear expansion. Suppose we want to bring the cube to its original size by heating. The temperature should be raised by
Answer» An external pressure $P$ is applied on a cube at $0^{o} C$ so that it is equally compressed from all sides. $K$ is the bulk modulus of the material of the cube and $α$ is its coefficient of linear expansion. Suppose we want to bring the cube to its original size by heating. The temperature should be raised by

Discussion

5.	What is an isochoric process?
Answer» What is an isochoric process?

Discussion

6.	(a) Draw a ray diagram depicting the formation of the image by an astronomical telescope in normal adjustment. (b) You are given the following three lenses. Which two lenses will you use as an eyepiece and as an objective to construct an astronomical telescope ? Give reason.
Answer» (a) Draw a ray diagram depicting the formation of the image by an astronomical telescope in normal adjustment. (b) You are given the following three lenses. Which two lenses will you use as an eyepiece and as an objective to construct an astronomical telescope ? Give reason.

Discussion

7.	A small piece of cesium metal (ϕ=1.9eV) is kept at a distance of 20 cm from a large metal plate having a charge density of 1.0 ×10−2Cm−2 on the surface facing the cesium piece. A monochromatic light of wavelength 400 nm is incident on the cesium piece. Find the minimum and the maximum kinetic energy of the photo electrons reaching the large metal plate. Neglect any change in electric field due to the small piece of cesium present.
Answer» A small piece of cesium metal ( $ϕ = 1.9 e V$ ) is kept at a distance of 20 cm from a large metal plate having a charge density of 1.0 $\times 10^{- 2} C m^{- 2}$ on the surface facing the cesium piece. A monochromatic light of wavelength 400 nm is incident on the cesium piece. Find the minimum and the maximum kinetic energy of the photo electrons reaching the large metal plate. Neglect any change in electric field due to the small piece of cesium present.

Discussion

8.	For the graph shown below, find the net change in angular velocity of the body during the entire motion.
Answer» For the graph shown below, find the net change in angular velocity of the body during the entire motion.

Discussion

9.	The diameter of the sun is 1.4×109 m and its distance from the earth is 1.5×1011 m. Find the radius of the image of the sun formed by a lens of focal length 20 cm.
Answer» The diameter of the sun is $1.4 \times 10^{9} m$ and its distance from the earth is $1.5 \times 10^{11} m$ . Find the radius of the image of the sun formed by a lens of focal length 20 cm.

Discussion

10.	The force between two charges separated by a distance 1 m is 1.8 N. The charges are in the ratio 1 : 2 .Then the charges are
Answer» The force between two charges separated by a distance 1 m is 1.8 N. The charges are in the ratio 1 : 2 .Then the charges are

Discussion

11.	An aluminium can of cylindrical shape contains 500 cm3 of water. The area of the inner cross section of the can is 125 cm 2. All measurements refer to 10∘C. Find the rise in the water level if the temperature increases to 80∘ C. The coefficient of linear expansion of aluminium = 23×10−6 ∘C−1 and the average coefficient of volume expansion of water =3.2×10−4 ∘C−1 respectively.
Answer» An aluminium can of cylindrical shape contains $500 c m^{3}$ of water. The area of the inner cross section of the can is 125 cm 2. All measurements refer to $10^{\circ} C$ . Find the rise in the water level if the temperature increases to $80^{\circ} C$ . The coefficient of linear expansion of aluminium = $23 \times 10^{- 6}^{\circ} C^{- 1}$ and the average coefficient of volume expansion of water $= 3.2 \times 10^{- 4}^{\circ} C^{- 1}$ respectively.

Discussion

12.	A 2 MeV proton is moving perpendicular to a uniform magnetic field of 2.5 T. The force on the proton is (mass of proton = 1.6×10−27kg)
Answer» A 2 MeV proton is moving perpendicular to a uniform magnetic field of 2.5 T. The force on the proton is (mass of proton = $1.6 \times 10^{- 27} k g$ )

Discussion

13.	A man running on a horizontal road at 8 km/h finds the rain falling vertically. He increases his speed to 12 km/h and finds that the drops make an angle 30∘ with the vertical. Find the speed of the rain with respect to the road (in km/hr).
Answer» A man running on a horizontal road at $8 km/h$ finds the rain falling vertically. He increases his speed to $12 km/h$ and finds that the drops make an angle $30^{\circ}$ with the vertical. Find the speed of the rain with respect to the road (in $km/hr$ ).

Discussion

14.	A uniform chain of length l and mass m overhangs a smooth table with its two third part lying on the table. Then the kinetic energy of the chain will be ′x′mgl then the value of ′x′ will be (it completely slips off the table)
Answer» A uniform chain of length $l$ and mass $m$ overhangs a smooth table with its two third part lying on the table. Then the kinetic energy of the chain will be $^{'} x^{'} m g l$ then the value of $^{'} x^{'}$ will be (it completely slips off the table)

Discussion

15.	A student measures the time period of 100 oscillations of a simple pendulum four times. The data set is 90s, 91s, 95s and 92 s. If the minimum division in the measuring clock is 1 s, then the reported mean time should be:
Answer» A student measures the time period of 100 oscillations of a simple pendulum four times. The data set is 90s, 91s, 95s and 92 s. If the minimum division in the measuring clock is 1 s, then the reported mean time should be:

Discussion

16.	In a rigid wire frame ABCDEFA, as shown in the figure, a current I0 flows through the wire from A to F as shown in the figure. Radii of the three quarters, AB, CD and EF are r1=314=314m and r3=1m respectively with common center at O. All the wires are light except for the portion ED which have a mass of ‘m’ kg. If this loop is kept in a magnetic field of magnitude 2T which is directed along positive y-axis, torque acting on the loop is
Answer» In a rigid wire frame ABCDEFA, as shown in the figure, a current I0 flows through the wire from A to F as shown in the figure. Radii of the three quarters, AB, CD and EF are $r_{1} = 3^{\frac{1}{4}} = 3^{\frac{1}{4}} m$ and $r_{3} = 1 m$ respectively with common center at O. All the wires are light except for the portion ED which have a mass of ‘m’ kg. If this loop is kept in a magnetic field of magnitude 2T which is directed along positive y-axis, torque acting on the loop is

16.

In a rigid wire frame ABCDEFA, as shown in the figure, a current I0 flows through the wire from A to F as shown in the figure. Radii of the three quarters, AB, CD and EF are r1=314=314m and r3=1m respectively with common center at O. All the wires are light except for the portion ED which have a mass of ‘m’ kg. If this loop is kept in a magnetic field of magnitude 2T which is directed along positive y-axis, torque acting on the loop is

Answer»

In a rigid wire frame ABCDEFA, as shown in the figure, a current I0 flows through the wire from A to F as shown in the figure. Radii of the three quarters, AB, CD and EF are $r_{1} = 3^{\frac{1}{4}} = 3^{\frac{1}{4}} m$ and $r_{3} = 1 m$ respectively with common center at O. All the wires are light except for the portion ED which have a mass of ‘m’ kg.

If this loop is kept in a magnetic field of magnitude 2T which is directed along positive y-axis, torque acting on the loop is

Discussion

17.	Air is filled at 60∘C in a vessel having a open mouth. The vessel is heated to a temperature T, so that 14th part of air escapes. Assuming the volume of vessel remains constant , the value of T(in ∘C) is
Answer» Air is filled at $60^{\circ} C$ in a vessel having a open mouth. The vessel is heated to a temperature $T,$ so that ${\frac{1}{4}}^{t h}$ part of air escapes. Assuming the volume of vessel remains constant , the value of $T (in^{\circ} C)$ is

Discussion

18.	A transistor-oscillator using a resonant circuit with an inductor L (of negligible resistance) and a capacitor C in series produce oscillations of frequency f . If L is doubled and C is changed to 4C, the frequency will be:
Answer» A transistor-oscillator using a resonant circuit with an inductor L (of negligible resistance) and a capacitor C in series produce oscillations of frequency f . If L is doubled and C is changed to 4C, the frequency will be:

Discussion

19.	A cord is used to lower vertically a block of mass M a distance d at a constant downward acceleration of g/4 . Then the work done by the tension in the cord on the block is
Answer» A cord is used to lower vertically a block of mass M a distance d at a constant downward acceleration of g/4 . Then the work done by the tension in the cord on the block is

Discussion

20.	A solid whose volume does not change with temperature floats in a liquid. For two different temperatures t1 and t2 of the liquid, fractions f1 and f2 of the volume of the solid remain submerged in the liquid. The coefficient of volume expansion of the liquid is equal to
Answer» A solid whose volume does not change with temperature floats in a liquid. For two different temperatures $t_{1} a n d t_{2}$ of the liquid, fractions $f_{1} a n d f_{2}$ of the volume of the solid remain submerged in the liquid. The coefficient of volume expansion of the liquid is equal to

Discussion

21.	If tan α=mm+1 and tan β=12m+1, then a possible value of (α+β) is
Answer» If $t a n α = \frac{m}{m + 1}$ and $t a n β = \frac{1}{2 m + 1}$ , then a possible value of $(α + β)$ is

Discussion

22.	An electron is moving along positive x - axis. A uniform electric field exists towards negative y - axis. What should be the direction of magnetic field of suitable magnitude so that net force on electron is zero?
Answer» An electron is moving along positive x - axis. A uniform electric field exists towards negative y - axis. What should be the direction of magnetic field of suitable magnitude so that net force on electron is zero?

Discussion

23.	When an additional charge of 1 μ C is given to a capacitor, its potential rises by 1mV. Then the capacitance of the capacitor in μ F is
Answer» When an additional charge of 1 $μ$ C is given to a capacitor, its potential rises by 1mV. Then the capacitance of the capacitor in $μ$ F is

Discussion

24.	uv graph for convex mirror is shown in figure. If the magnification of a real object placed at 25 cm from mirror is (4x), then x is:
Answer» uv graph for convex mirror is shown in figure. If the magnification of a real object placed at $25 cm$ from mirror is $(\frac{4}{x})$ , then $x$ is:

Discussion

25.	A metal plate is exposed to light with wavelength λ. It is observed that electrons are ejected from the surface of the plate. When a retarding uniform electric field E is applied, no electron can move away from the plate farther than a certain distance d. Then the threshold wavelength λ0 for the material of plate is (e is the electronic charge, h is the Plank’s constant and c is the speed of light.)
Answer» A metal plate is exposed to light with wavelength $λ$ . It is observed that electrons are ejected from the surface of the plate. When a retarding uniform electric field $E$ is applied, no electron can move away from the plate farther than a certain distance $d$ . Then the threshold wavelength $λ_{0}$ for the material of plate is ( $e$ is the electronic charge, $h$ is the Plank’s constant and $c$ is the speed of light.)

Discussion

26.	A thin uniform rod of length L and mass M is bent at length ratio 1:2 such that the angle between them is 90∘. The moment of inertia of the bent rod about an axis passes through the bending point and perpendicular to the plane is
Answer» A thin uniform rod of length $L$ and mass $M$ is bent at length ratio $1 : 2$ such that the angle between them is $90^{\circ}$ . The moment of inertia of the bent rod about an axis passes through the bending point and perpendicular to the plane is

Discussion

27.	The diagram shows the displacement-time graph for a particle moving in a straight line. The average velocity for the interval t=2 s to t=5 s is (Displacement is in m and time is in s)
Answer» The diagram shows the displacement-time graph for a particle moving in a straight line. The average velocity for the interval $t = 2 s$ to $t = 5 s$ is (Displacement is in $m$ and time is in $s$ )

Discussion

28.	An emf of 5 V is produced by an inductor due to self inductance, when the current changes at a steady rate from 3 A to 2 A in 1 ms. The value of self inductance of inductor is
Answer» An emf of $5 V$ is produced by an inductor due to self inductance, when the current changes at a steady rate from $3 A$ to $2 A$ in $1 ms$ . The value of self inductance of inductor is

Discussion

29.	In the figure shown, find the force exerted by the pulley at the support. Make necessary assumptions and take g=10 m/s2 .
Answer» In the figure shown, find the force exerted by the pulley at the support. Make necessary assumptions and take $g = 10 m / s^{2}$ .

Discussion

30.	A bullet of mass 20 g strikes a pendulum of mass 5 kg. The center of mass of the pendulum rises a vertical distance of 10 cm. If the bullet gets embedded into the pendulum, calculate the initial speed of the bullet.
Answer» A bullet of mass $20 g$ strikes a pendulum of mass $5 kg$ . The center of mass of the pendulum rises a vertical distance of $10 cm$ . If the bullet gets embedded into the pendulum, calculate the initial speed of the bullet.

Discussion

31.	Suppose the acceleration due to gravity at a place is 10 m/s2. Find its value in cm/(minute)2.
Answer» Suppose the acceleration due to gravity at a place is 10 $m / s^{2}$ . Find its value in cm/ ${(minute)}^{2}$ .

Discussion

32.	Which of the following correctly represents the FBD of mass m.
Answer» Which of the following correctly represents the $F B D$ of mass $m$ .

Discussion

33.	According to the theory of relativity if any particle moves at speed nearer to the speed of light, then its mass increases. But in an atom, the electrons are moving at speed near to the speed of light. Then why doesn't the mass increase?
Answer» According to the theory of relativity if any particle moves at speed nearer to the speed of light, then its mass increases. But in an atom, the electrons are moving at speed near to the speed of light. Then why doesn't the mass increase?

Discussion

34.	A body dropped from rest at tuop of the tower falls 1/2 of its total distance in last second of fall. Find time of flight and total height of tower.
Answer» A body dropped from rest at tuop of the tower falls 1/2 of its total distance in last second of fall. Find time of flight and total height of tower.

Discussion

35.	For skywave propagation of a 10 MHz signal, what should be the minimum electron density in ionosphere?
Answer» For skywave propagation of a $10 M H z$ signal, what should be the minimum electron density in ionosphere?

Discussion

36.	A biker is performing stunt in a cylindrical death well of radius 16 m. If speed of biker is constant and coefficient of friction of well's surface is 0.2, find the minimum speed required to perform the stunt safely.
Answer» A biker is performing stunt in a cylindrical death well of radius $16 m$ . If speed of biker is constant and coefficient of friction of well's surface is $0.2$ , find the minimum speed required to perform the stunt safely.

Discussion

37.	A car starts from rest and accelerates uniformly for 10s to a velocity of 36km/hr .It then runs at constant velocity and finally comes to rest in 50m with constant retardation . Find The total acceleration, time taken and retardation of car.
Answer» A car starts from rest and accelerates uniformly for 10s to a velocity of 36km/hr .It then runs at constant velocity and finally comes to rest in 50m with constant retardation . Find The total acceleration, time taken and retardation of car.

Discussion

38.	Sir if I have conducting straight wire and I push it with some velocity in a gravity free space and magnetic fields are present perpendicular to the length of conducting wire. . Then what is the trajectory of wire or how will the wire move in space. What if that wire is not straight , if it is semicircular then how will that move in space.
Answer» Sir if I have conducting straight wire and I push it with some velocity in a gravity free space and magnetic fields are present perpendicular to the length of conducting wire. . Then what is the trajectory of wire or how will the wire move in space. What if that wire is not straight , if it is semicircular then how will that move in space.

38.

Sir if I have conducting straight wire and I push it with some velocity in a gravity free space and magnetic fields are present perpendicular to the length of conducting wire. . Then what is the trajectory of wire or how will the wire move in space. What if that wire is not straight , if it is semicircular then how will that move in space.

Answer»

Sir if I have conducting straight wire and I push it with some velocity in a gravity free space and magnetic fields are present perpendicular to the length of conducting wire. . Then what is the trajectory of wire or how will the wire move in space.

What if that wire is not straight , if it is semicircular then how will that move in space.

Discussion

39.	Water flows out of a big tank along a horizontal tube AB of length l and radius r and bent at right angles at the other end as shown in the figure. The rate of flowis Q m3 /s. Calculate the moment of the force exerted by the water on the tube about the end A.
Answer» Water flows out of a big tank along a horizontal tube AB of length l and radius r and bent at right angles at the other end as shown in the figure. The rate of flowis Q m³ /s. Calculate the moment of the force exerted by the water on the tube about the end A.

Discussion

40.	Three hollow spheres of same mass and radius are placed as shown in figure. Find the COM of the system.
Answer» Three hollow spheres of same mass and radius are placed as shown in figure. Find the $C O M$ of the system.

Discussion

41.	The output characteristic for a common emitter transistor is shown in the given figure. Use the graph to find out the current amplification factor for the transistor when VCE = 2 V.
Answer» The output characteristic for a common emitter transistor is shown in the given figure. Use the graph to find out the current amplification factor for the transistor when V_CE = 2 V.

41.

The output characteristic for a common emitter transistor is shown in the given figure. Use the graph to find out the current amplification factor for the transistor when VCE = 2 V.

Answer»

The output characteristic for a common emitter transistor is shown in the given figure.

Use the graph to find out the current amplification factor for the transistor when V_CE = 2 V.

Discussion

42.	A particle's kinetic energy decreases when an external force is exerterted on it. Is the force conservative or non conservative? Explain.
Answer» A particle's kinetic energy decreases when an external force is exerterted on it. Is the force conservative or non conservative? Explain.

Discussion

43.	If →A=9^i−7^j+5^k and →B=3^i−2^j−6^k, then the value of (→A+→B)⋅(→A−→B) is
Answer» If $\to A = 9^i - 7^j + 5^k$ and $\to B = 3^i - 2^j - 6^k$ , then the value of $(\to A + \to B) \cdot (\to A - \to B)$ is

Discussion

44.	A motor boat going downstream overcomes a float at a point A. 60 minutes later it turns and after some time passes the float at a distance of 12 km from the point A. The velocity of the stream is (assuming constant velocity for the boat in still water ) (1) 6 km/h (2) 3 km/h (3) 4 km/h (4) 2 km/h
Answer» A motor boat going downstream overcomes a float at a point A. 60 minutes later it turns and after some time passes the float at a distance of 12 km from the point A. The velocity of the stream is (assuming constant velocity for the boat in still water ) (1) 6 km/h (2) 3 km/h (3) 4 km/h (4) 2 km/h

Discussion

45.	Choose the word which is MOST OPPOSITE in MEANING to the word as used in the passage: Prudent
Answer» Choose the word which is MOST OPPOSITE in MEANING to the word as used in the passage: Prudent

45.

Choose the word which is MOST OPPOSITE in MEANING to the word as used in the passage: Prudent

Answer»

Choose the word which is MOST OPPOSITE in MEANING to the word as used in the passage:

Prudent

Discussion

46.	The extension in a string obeying Hooke's law is x. The speed of a transverse wave in a stretched string is v. If the extension in the string is increased to 1.5x, the speed of the wave will be
Answer» The extension in a string obeying Hooke's law is x. The speed of a transverse wave in a stretched string is v. If the extension in the string is increased to 1.5x, the speed of the wave will be

Discussion

47.	Why do we call an ammeter a low resistance galvanometer?
Answer» Why do we call an ammeter a low resistance galvanometer?

Discussion

48.	An impulsive force (F) acts on a body which changes with time (t). The F−t graph is shown below. The value of impulse in time π sec will be
Answer» An impulsive force $(F)$ acts on a body which changes with time $(t)$ . The $F - t$ graph is shown below. The value of impulse in time $π sec$ will be

Discussion

49.	A bent wire PQ carrying a current I is placed in a region of uniform magnetic field →B having magnitude B . The force on the wire PQ is n×BIL .The value of n is
Answer» A bent wire PQ carrying a current I is placed in a region of uniform magnetic field $\to B$ having magnitude B . The force on the wire PQ is $n \times B I L$ .The value of n is

49.

A bent wire PQ carrying a current I is placed in a region of uniform magnetic field →B having magnitude B . The force on the wire PQ is n×BIL .The value of n is

Answer»

A bent wire PQ carrying a current I is placed in a region of uniform magnetic field $\to B$ having magnitude B . The force on the wire PQ is $n \times B I L$ .The value of n is

Discussion

50.	The blades of a windmill sweep out a circle of area A. (a) If the wind flows at a velocity v perpendicular to the circle, what is the mass of the air passing through it in time t?(b) What is the kinetic energy of the air? (c) Assume that the windmill converts 25% of the wind’s energy into electrical energy, and that A=30m2, v = 36 km/h and the density of air is 1.2 kgm−3. What is the electrical power produced?
Answer» The blades of a windmill sweep out a circle of area A. (a) If the wind flows at a velocity v perpendicular to the circle, what is the mass of the air passing through it in time t?(b) What is the kinetic energy of the air? (c) Assume that the windmill converts 25% of the wind’s energy into electrical energy, and that $A = 30 m^{2}$ , v = 36 km/h and the density of air is $1.2 k g m^{- 3}$ . What is the electrical power produced?

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A wave yi = 0.3 cos (40t − 0.2x) is travelling along a string toward a boundary at x = 0. What are the expressions for the reflected waves if the string has a fixed end and at x = 0. Assume SI units.

Figure shows a loop-the-loop track of radius R. A car (without engine) starts from a platform at a distance h above the top of the loop and goes around the loop without falling off the track. Find the minimum value of h for a successful looping. Neglect friction.

The bob of a pendulum of length, I is pulled aside from its equilibrium position through an angle θ and then released. what will be the speed V of the bob when it pass through its equilibrium condition.

An external pressure P is applied on a cube at 0oC so that it is equally compressed from all sides. K is the bulk modulus of the material of the cube and α is its coefficient of linear expansion. Suppose we want to bring the cube to its original size by heating. The temperature should be raised by

What is an isochoric process?

(a) Draw a ray diagram depicting the formation of the image by an astronomical telescope in normal adjustment. (b) You are given the following three lenses. Which two lenses will you use as an eyepiece and as an objective to construct an astronomical telescope ? Give reason.

For the graph shown below, find the net change in angular velocity of the body during the entire motion.

The diameter of the sun is 1.4×109 m and its distance from the earth is 1.5×1011 m. Find the radius of the image of the sun formed by a lens of focal length 20 cm.

The force between two charges separated by a distance 1 m is 1.8 N. The charges are in the ratio 1 : 2 .Then the charges are

A 2 MeV proton is moving perpendicular to a uniform magnetic field of 2.5 T. The force on the proton is (mass of proton = 1.6×10−27kg)

A man running on a horizontal road at 8 km/h finds the rain falling vertically. He increases his speed to 12 km/h and finds that the drops make an angle 30∘ with the vertical. Find the speed of the rain with respect to the road (in km/hr).

A uniform chain of length l and mass m overhangs a smooth table with its two third part lying on the table. Then the kinetic energy of the chain will be ′x′mgl then the value of ′x′ will be (it completely slips off the table)

A student measures the time period of 100 oscillations of a simple pendulum four times. The data set is 90s, 91s, 95s and 92 s. If the minimum division in the measuring clock is 1 s, then the reported mean time should be:

Air is filled at 60∘C in a vessel having a open mouth. The vessel is heated to a temperature T, so that 14th part of air escapes. Assuming the volume of vessel remains constant , the value of T(in ∘C) is

A transistor-oscillator using a resonant circuit with an inductor L (of negligible resistance) and a capacitor C in series produce oscillations of frequency f . If L is doubled and C is changed to 4C, the frequency will be:

A cord is used to lower vertically a block of mass M a distance d at a constant downward acceleration of g/4 . Then the work done by the tension in the cord on the block is

A solid whose volume does not change with temperature floats in a liquid. For two different temperatures t1 and t2 of the liquid, fractions f1 and f2 of the volume of the solid remain submerged in the liquid. The coefficient of volume expansion of the liquid is equal to

If tan α=mm+1 and tan β=12m+1, then a possible value of (α+β) is

An electron is moving along positive x - axis. A uniform electric field exists towards negative y - axis. What should be the direction of magnetic field of suitable magnitude so that net force on electron is zero?

When an additional charge of 1 μ C is given to a capacitor, its potential rises by 1mV. Then the capacitance of the capacitor in μ F is

uv graph for convex mirror is shown in figure. If the magnification of a real object placed at 25 cm from mirror is (4x), then x is:

A thin uniform rod of length L and mass M is bent at length ratio 1:2 such that the angle between them is 90∘. The moment of inertia of the bent rod about an axis passes through the bending point and perpendicular to the plane is

The diagram shows the displacement-time graph for a particle moving in a straight line. The average velocity for the interval t=2 s to t=5 s is (Displacement is in m and time is in s)

An emf of 5 V is produced by an inductor due to self inductance, when the current changes at a steady rate from 3 A to 2 A in 1 ms. The value of self inductance of inductor is

In the figure shown, find the force exerted by the pulley at the support. Make necessary assumptions and take g=10 m/s2 .

A bullet of mass 20 g strikes a pendulum of mass 5 kg. The center of mass of the pendulum rises a vertical distance of 10 cm. If the bullet gets embedded into the pendulum, calculate the initial speed of the bullet.

Suppose the acceleration due to gravity at a place is 10 m/s2. Find its value in cm/(minute)2.

Which of the following correctly represents the FBD of mass m.

According to the theory of relativity if any particle moves at speed nearer to the speed of light, then its mass increases. But in an atom, the electrons are moving at speed near to the speed of light. Then why doesn't the mass increase?

A body dropped from rest at tuop of the tower falls 1/2 of its total distance in last second of fall. Find time of flight and total height of tower.

For skywave propagation of a 10 MHz signal, what should be the minimum electron density in ionosphere?

A biker is performing stunt in a cylindrical death well of radius 16 m. If speed of biker is constant and coefficient of friction of well's surface is 0.2, find the minimum speed required to perform the stunt safely.

A car starts from rest and accelerates uniformly for 10s to a velocity of 36km/hr .It then runs at constant velocity and finally comes to rest in 50m with constant retardation . Find The total acceleration, time taken and retardation of car.

Water flows out of a big tank along a horizontal tube AB of length l and radius r and bent at right angles at the other end as shown in the figure. The rate of flowis Q m3 /s. Calculate the moment of the force exerted by the water on the tube about the end A.

Three hollow spheres of same mass and radius are placed as shown in figure. Find the COM of the system.

The output characteristic for a common emitter transistor is shown in the given figure. Use the graph to find out the current amplification factor for the transistor when VCE = 2 V.

A particle's kinetic energy decreases when an external force is exerterted on it. Is the force conservative or non conservative? Explain.

If →A=9^i−7^j+5^k and →B=3^i−2^j−6^k, then the value of (→A+→B)⋅(→A−→B) is

A motor boat going downstream overcomes a float at a point A. 60 minutes later it turns and after some time passes the float at a distance of 12 km from the point A. The velocity of the stream is (assuming constant velocity for the boat in still water ) (1) 6 km/h (2) 3 km/h (3) 4 km/h (4) 2 km/h

Choose the word which is MOST OPPOSITE in MEANING to the word as used in the passage: Prudent

The extension in a string obeying Hooke's law is x. The speed of a transverse wave in a stretched string is v. If the extension in the string is increased to 1.5x, the speed of the wave will be

Why do we call an ammeter a low resistance galvanometer?

An impulsive force (F) acts on a body which changes with time (t). The F−t graph is shown below. The value of impulse in time π sec will be

A bent wire PQ carrying a current I is placed in a region of uniform magnetic field →B having magnitude B . The force on the wire PQ is n×BIL .The value of n is