50278 + Interview Questions in Physics Page 216 InterviewSolution

10751.	A winding wire which is used to frame a long solenoid can withstand a maximum current of10 A. If the length of solenoid is 80 cm and its cross- sectional radius is 3 cm, then find the required length of the winding wire if the magnetic field inside the solenoid near its axis is 0.2 T.
Answer» A winding wire which is used to frame a long solenoid can withstand a maximum current of $10 A$ . If the length of solenoid is $80 cm$ and its cross- sectional radius is $3 cm$ , then find the required length of the winding wire if the magnetic field inside the solenoid near its axis is $0.2 T$ .

Discussion

10752.	Equation of a stationary wave is given by y=5cos(πx25)sin(100πt). Here, x is in cm and t in s. Node will not occur at distance
Answer» Equation of a stationary wave is given by $y = 5 cos (\frac{π x}{25}) sin (100 π t)$ . Here, $x$ is in $cm$ and $t$ in $s$ . Node will not occur at distance

Discussion

10753.	W is workdone in blowing a bubble of radius R .If bubble radius changed to 2R then work done will be
Answer» W is workdone in blowing a bubble of radius R .If bubble radius changed to 2R then work done will be

Discussion

10754.	Four particle of equal mass are moving round a circle of radius r due to their mutual gravitational attraction.Find the angular velocity of each particle?
Answer» Four particle of equal mass are moving round a circle of radius r due to their mutual gravitational attraction.Find the angular velocity of each particle?

Discussion

10755.	The threshold frequency of a metal is 810 power 14 Hz. What is the kinetic energy of an electron emitted having frequency 110 power 15 Hz
Answer» The threshold frequency of a metal is 810 power 14 Hz. What is the kinetic energy of an electron emitted having frequency 110 power 15 Hz

Discussion

10756.	Two parallel infinite line charges with linear charge densities +λ C/m and -λ C/m are placed at a dis†an ce of 2R in free space what is the electric field mid way between the two line charges
Answer» Two parallel infinite line charges with linear charge densities +λ C/m and -λ C/m are placed at a dis†an ce of 2R in free space what is the electric field mid way between the two line charges

Discussion

10757.	Three equal positive charges of magnitude q are placed at the corner of an equilateral triangle.determine the charge that should be placed at the center of triangle. So that system is in the state of equilibrium.
Answer» Three equal positive charges of magnitude q are placed at the corner of an equilateral triangle.determine the charge that should be placed at the center of triangle. So that system is in the state of equilibrium.

Discussion

10758.	The length of a simple pendulum is decreased by 0.5 % at what height should the pendulum should be carried show the time period remain unchanged
Answer» The length of a simple pendulum is decreased by 0.5 % at what height should the pendulum should be carried show the time period remain unchanged

Discussion

10759.	A particle moves along a semicircle of radius 10 m in 5 seconds. The average velocity of the particle is
Answer» A particle moves along a semicircle of radius $10 m$ in 5 seconds. The average velocity of the particle is

Discussion

10760.	in LC circuit ,find time when energy store is completely electrical
Answer» in LC circuit ,find time when energy store is completely electrical

Discussion

10761.	An electric dipole having charge +q and -q are at a separation r . At a distance d>>r along the axis of the dipoledipole the field is proportional to
Answer» An electric dipole having charge +q and -q are at a separation r . At a distance d>>r along the axis of the dipoledipole the field is proportional to

Discussion

10762.	A cannon ball of mass 2 kg is fired at a target 500 m away. The 400 kg cannon recoils with a velocity of 2 ms−1. Assuming cannon ball moves with constant velocity, when will it hit the target?
Answer» A cannon ball of mass $2 k g$ is fired at a target $500 m$ away. The $400 k g$ cannon recoils with a velocity of $2 m s^{- 1}$ . Assuming cannon ball moves with constant velocity, when will it hit the target?

Discussion

10763.	Stone-1 is dropped from the roof of a building, after 4 seconds Stone-2 is dropped from the same roof. Which of the following is/are correct?
Answer» Stone-1 is dropped from the roof of a building, after 4 seconds Stone-2 is dropped from the same roof. Which of the following is/are correct?

Discussion

10764.	A particle is thrown up with a certain velocity and at an angle θ with the horizontal . The variation of kinetic energy (E) with time (t) is given by
Answer» A particle is thrown up with a certain velocity and at an angle $θ$ with the horizontal . The variation of kinetic energy $(E)$ with time $(t)$ is given by

Discussion

10765.	All surfaces shown in the figure are frictionless. Ablock of mass 2 kg is kept on a wedge of mass10 kg. If the mass m remains stationary w.rt. wedgethe magnitude of force P is (g = 10 m/s)kgTH kg(2) 90 N(1) 15 N(4) 45 N(3) 12 N
Answer» All surfaces shown in the figure are frictionless. Ablock of mass 2 kg is kept on a wedge of mass10 kg. If the mass m remains stationary w.rt. wedgethe magnitude of force P is (g = 10 m/s)kgTH kg(2) 90 N(1) 15 N(4) 45 N(3) 12 N

Discussion

10766.	88.A coil has an inductance of 0.7 H and is joined in series with a resistance of 220 When an alternating e.m.f. of 220 V at 50 cps is applied to it, then the wattless component of the current in the circuit is- a. 5A b. 0.5A c. 0.7A d. 7A
Answer» 88.A coil has an inductance of 0.7 H and is joined in series with a resistance of 220 When an alternating e.m.f. of 220 V at 50 cps is applied to it, then the wattless component of the current in the circuit is- a. 5A b. 0.5A c. 0.7A d. 7A

Discussion

10767.	The potential energy ofa particle of mass m1kg is moving alongx-axis given by U(x)=\lbrack x^2/2-x\rbrack J.If total mechanical energy of particle is 2J,then find its maximum speed.
Answer» The potential energy ofa particle of mass m1kg is moving alongx-axis given by U(x)=\lbrack x^2/2-x\rbrack J.If total mechanical energy of particle is 2J,then find its maximum speed.

Discussion

10768.	Sounds from two identical sources S1 and S2 reach a point P directly in the same phase with net intensity I0 .The power of S1 is now reduced to 64% of its initial value, and the phase difference between S1 and S2 is varied continuously. The maximum and minimum intensities now recorded at P are Imax and Imin respectively. Then
Answer» Sounds from two identical sources $S_{1} a n d S_{2}$ reach a point P directly in the same phase with net intensity $I_{0}$ .The power of S1 is now reduced to $64 %$ of its initial value, and the phase difference between $S_{1} a n d S_{2}$ is varied continuously. The maximum and minimum intensities now recorded at P are Imax and Imin respectively. Then

Discussion

10769.	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

10770.	The approximate change in volume V of a cube of sides x meters caused by increasing the side by 1% is
Answer» The approximate change in volume $V$ of a cube of sides $x$ meters caused by increasing the side by $1 %$ is

Discussion

10771.	For a plane electromagnetic wave propagating in x-direction, which one of the following combination gives the correct possible directions for electric field (E) and magnetic field (B) respectively?
Answer» For a plane electromagnetic wave propagating in $x$ -direction, which one of the following combination gives the correct possible directions for electric field $(E)$ and magnetic field $(B)$ respectively?

Discussion

10772.	eq wt of B(OH)3 IS
Answer» eq wt of B(OH)3 IS

Discussion

10773.	A force →F=(5^i+3^j+2^k) N is applied over a particle which displaces it from origin to the point →r=(2^i−^j) m. The work done on the particle is
Answer» A force $\to F = (5^i + 3^j + 2^k) N$ is applied over a particle which displaces it from origin to the point $\to r = (2^i -^j) m$ . The work done on the particle is

Discussion

10774.	In a flash type ADC, an analog input is to be converted into 4− bit digital output, then number of op-amp comparators required in ADC will be _____15
Answer» In a flash type ADC, an analog input is to be converted into $4 -$ bit digital output, then number of op-amp comparators required in ADC will be _____ 15

Discussion

10775.	Suppose the charge of a proton and an electron differ slightly. One of them is −e, the other is (e+Δe). If the resultant of electrostatic force and gravitational force between two hydrogen atoms placed at a distance d (much greater than atomic size) apart is zero, then Δe is of the order of [Given mass of hydrogen mh=1.67×10−27 kg]
Answer» Suppose the charge of a proton and an electron differ slightly. One of them is $- e$ , the other is $(e + Δ e)$ . If the resultant of electrostatic force and gravitational force between two hydrogen atoms placed at a distance $d$ (much greater than atomic size) apart is zero, then $Δ e$ is of the order of [Given mass of hydrogen $m_{h} = 1.67 \times 10^{- 27} k g$ ]

Discussion

10776.	A boat's propeller has a rotational inertia of 4 kg-m2. After a constant torque is applied for 12 s, the propeller's angular speed changes from a clockwise 8 rad/s to counter-clock wise 8 rad/s. What was the torque applied to the propeller?
Answer» A boat's propeller has a rotational inertia of $4 {kg-m}^{2}$ . After a constant torque is applied for $12 s$ , the propeller's angular speed changes from a clockwise $8 rad/s$ to counter-clock wise $8 rad/s$ . What was the torque applied to the propeller?

Discussion

10777.	64.A short electric dipole of dipole moment p kept in plane of a wire of linear charge density lambda as shown. The dipole makes angle 60 with local electric field. If distance of dipole from the wire is R, then force experianced by dipole is
Answer» 64.A short electric dipole of dipole moment p kept in plane of a wire of linear charge density lambda as shown. The dipole makes angle 60 with local electric field. If distance of dipole from the wire is R, then force experianced by dipole is

Discussion

10778.	find the torque acting on a charged particle-q revolving around a charge Q in an elliptical orbit
Answer» find the torque acting on a charged particle-q revolving around a charge Q in an elliptical orbit

Discussion

10779.	A body is moving with uniform retardation covers 3km before it's speed is reduced to half of its initial value it comes to rest in another distance of
Answer» A body is moving with uniform retardation covers 3km before it's speed is reduced to half of its initial value it comes to rest in another distance of

Discussion

10780.	A certain transverse sinusoidal wave of wavelength 20 cm is moving in the positive x direction. The transverse velocity of the particle at x = 0 as a function of time is shown. The amplitude of the motion is:
Answer» A certain transverse sinusoidal wave of wavelength 20 cm is moving in the positive x direction. The transverse velocity of the particle at x = 0 as a function of time is shown. The amplitude of the motion is:

Discussion

10781.	At what height from the Earth's surface the solution due to gravity decreases by 1%
Answer» At what height from the Earth's surface the solution due to gravity decreases by 1%

Discussion

10782.	An object of size 3.0cm is placed 14cm in front of a concave lens of focal length 21cm. Describe the image produced by the lens. Whathappens if the object is moved further away from the lens?
Answer» An object of size 3.0cm is placed 14cm in front of a concave lens of focal length 21cm. Describe the image produced by the lens. Whathappens if the object is moved further away from the lens?

Discussion

10783.	A body of mass 5 kg is moving in a circle of radius 1m with an angular velocity of 2 radian/sec. The centripetal force is
Answer» A body of mass 5 kg is moving in a circle of radius 1m with an angular velocity of 2 radian/sec. The centripetal force is

Discussion

10784.	The nearest star to our solar system is 4.29 light years away. How much is this distance in terms of parsecs? How much parallax would this star (named Alpha Centauri) show when viewed from two locations of the Earth six months apart in its orbit around the Sun ?
Answer» The nearest star to our solar system is 4.29 light years away. How much is this distance in terms of parsecs? How much parallax would this star (named Alpha Centauri) show when viewed from two locations of the Earth six months apart in its orbit around the Sun ?

Discussion

10785.	Can a body with zero initial velocity show 2D motion
Answer» Can a body with zero initial velocity show 2D motion

Discussion

10786.	A 250 gm grasshopper moving due south at 20 cm/s (in mid air) collides with another 150 gm grasshopper moving at a speed of 60 cm/s due north. Find the decrease in KE if they move together after collision.
Answer» A $250 gm$ grasshopper moving due south at $20 cm/s$ (in mid air) collides with another $150 gm$ grasshopper moving at a speed of $60 cm/s$ due north. Find the decrease in KE if they move together after collision.

Discussion

10787.	In the given circuit ,which is a part of a closed circuit. find the currents i1 and i2.
Answer» In the given circuit ,which is a part of a closed circuit. find the currents $i_{1}$ and $i_{2}$ .

Discussion

10788.	A small stone of mass 200 g is tied to one end of a string of length 80 cm. Holding the other end in the hand, the stone is whirled in a vertical circle. What is the minimum speed that needs to be imparted at the lowest point such that the stone is just able to complete the vertical circle?(Take g=10 m/s2)
Answer» A small stone of mass $200 g$ is tied to one end of a string of length $80 cm$ . Holding the other end in the hand, the stone is whirled in a vertical circle. What is the minimum speed that needs to be imparted at the lowest point such that the stone is just able to complete the vertical circle?(Take $g = 10 m / s^{2}$ )

Discussion

10789.	Prove that net electric field at the centre of a triangle is zero if charges of magnitude q are kept at its vertices
Answer» Prove that net electric field at the centre of a triangle is zero if charges of magnitude q are kept at its vertices

Discussion

10790.	Tap on the bubbles which give the answer as 100.
Answer» Tap on the bubbles which give the answer as 100.

Discussion

10791.	A man in a balloon, throws a stone downwards with speed of 5 m/s with tespect ot balloon. The balloon is moving upwards with a constant acceleration of 5m/s2 . Then velocity of the stone relative to the man after 2 second is
Answer» A man in a balloon, throws a stone downwards with speed of 5 m/s with tespect ot balloon. The balloon is moving upwards with a constant acceleration of $5 m / s^{2}$ . Then velocity of the stone relative to the man after 2 second is

Discussion

10792.	Two discs of moment of inertia I1 and I2 about their respective axes which are passing through centre and perpendicular to surface, rotating with angular frequencies ω1 and ω2 respectively, are brought into contact face to face with their axes of rotation coincident. The angular frequency of the composite disc will be
Answer» Two discs of moment of inertia $I_{1}$ and $I_{2}$ about their respective axes which are passing through centre and perpendicular to surface, rotating with angular frequencies $ω_{1}$ and $ω_{2}$ respectively, are brought into contact face to face with their axes of rotation coincident. The angular frequency of the composite disc will be

Discussion

10793.	A hot air balloon is ascending at the rate 42 m/s and is 80 m above the ground when a package is dropped over the side. (a) How long does the package take to reach the ground? (b) With what speed does it hit the ground?
Answer» A hot air balloon is ascending at the rate 42 m/s and is 80 m above the ground when a package is dropped over the side. (a) How long does the package take to reach the ground? (b) With what speed does it hit the ground?

Discussion

10794.	In a double star system of two stars of masses m and 2m, rotating about their centre of mass. Their time period of rotation about their centre of mass will be proportional to
Answer» In a double star system of two stars of masses m and 2m, rotating about their centre of mass. Their time period of rotation about their centre of mass will be proportional to

Discussion

10795.	In the circuit shown here, the point C is kept connected to point A till the current flowing through the circuit become constant. Afterward, suddenly point C disconnected from point A and connected to point B at time t=0. Ratio of the voltage across resistance and the inductor at t=LR will be equal to
Answer» In the circuit shown here, the point $C$ is kept connected to point $A$ till the current flowing through the circuit become constant. Afterward, suddenly point $C$ disconnected from point $A$ and connected to point $B$ at time $t = 0$ . Ratio of the voltage across resistance and the inductor at $t = \frac{L}{R}$ will be equal to

Discussion

10796.	A bent wire AB carrying a current I is placed in a region of uniform magnetic field →B. The force on the wire AB is
Answer» A bent wire AB carrying a current I is placed in a region of uniform magnetic field $\to B$ . The force on the wire AB is

10796.

A bent wire AB carrying a current I is placed in a region of uniform magnetic field →B. The force on the wire AB is

Answer»

A bent wire AB carrying a current I is placed in a region of uniform magnetic field $\to B$ . The force on the wire AB is

Discussion

10797.	A 2.0 kg block is dropped from a height of 40 cm onto a spring of spring consant k=1960 N/m. Find the maximum distance the spring is compressed.
Answer» A $2.0 kg$ block is dropped from a height of $40 cm$ onto a spring of spring consant $k = 1960 N/m$ . Find the maximum distance the spring is compressed.

Discussion

10798.	Consider a spherical gaseous cloud of mass density ρ(r) in free space, where r is the radial distance from its centre. The gaseous cloud is made of particles of equal mass m moving in circular orbits about the common center with the same kinetic energy K. The force acting on the particles is their mutual gravitational force. If ρ(r) is constant in time, the particle number density n(r)=ρ(r)/m is [G is universal gravitational constant]
Answer» Consider a spherical gaseous cloud of mass density $ρ (r)$ in free space, where $r$ is the radial distance from its centre. The gaseous cloud is made of particles of equal mass $m$ moving in circular orbits about the common center with the same kinetic energy $K$ . The force acting on the particles is their mutual gravitational force. If $ρ (r)$ is constant in time, the particle number density $n (r) = ρ (r) / m$ is [ $G$ is universal gravitational constant]

Discussion

10799.	a force f=6t^2i^ +4tj^ acts on a particle of mass 3 kg. What will be the velocity of the particle at t=3 second if at t=0, the particle was at rest; 1)18i^+6J^ 2)18i^+121j^ 3)12i^ +6j^ 4)none
Answer» a force f=6t^2i^ +4tj^ acts on a particle of mass 3 kg. What will be the velocity of the particle at t=3 second if at t=0, the particle was at rest; 1)18i^+6J^ 2)18i^+121j^ 3)12i^ +6j^ 4)none

Discussion

10800.	A certain gas takes three times as long to effuse out as helium. It's molecular mass will be
Answer» A certain gas takes three times as long to effuse out as helium. It's molecular mass will be

Discussion

Explore topic-wise InterviewSolutions in .

A winding wire which is used to frame a long solenoid can withstand a maximum current of10 A. If the length of solenoid is 80 cm and its cross- sectional radius is 3 cm, then find the required length of the winding wire if the magnetic field inside the solenoid near its axis is 0.2 T.

Equation of a stationary wave is given by y=5cos(πx25)sin(100πt). Here, x is in cm and t in s. Node will not occur at distance

W is workdone in blowing a bubble of radius R .If bubble radius changed to 2R then work done will be

Four particle of equal mass are moving round a circle of radius r due to their mutual gravitational attraction.Find the angular velocity of each particle?

The threshold frequency of a metal is 810 power 14 Hz. What is the kinetic energy of an electron emitted having frequency 110 power 15 Hz

Two parallel infinite line charges with linear charge densities +λ C/m and -λ C/m are placed at a dis†an ce of 2R in free space what is the electric field mid way between the two line charges

Three equal positive charges of magnitude q are placed at the corner of an equilateral triangle.determine the charge that should be placed at the center of triangle. So that system is in the state of equilibrium.

The length of a simple pendulum is decreased by 0.5 % at what height should the pendulum should be carried show the time period remain unchanged

A particle moves along a semicircle of radius 10 m in 5 seconds. The average velocity of the particle is

in LC circuit ,find time when energy store is completely electrical

An electric dipole having charge +q and -q are at a separation r . At a distance d>>r along the axis of the dipoledipole the field is proportional to

A cannon ball of mass 2 kg is fired at a target 500 m away. The 400 kg cannon recoils with a velocity of 2 ms−1​. Assuming cannon ball moves with constant velocity, when will it hit the target?

Stone-1 is dropped from the roof of a building, after 4 seconds Stone-2 is dropped from the same roof. Which of the following is/are correct?

A particle is thrown up with a certain velocity and at an angle θ with the horizontal . The variation of kinetic energy (E) with time (t) is given by

All surfaces shown in the figure are frictionless. Ablock of mass 2 kg is kept on a wedge of mass10 kg. If the mass m remains stationary w.rt. wedgethe magnitude of force P is (g = 10 m/s)kgTH kg(2) 90 N(1) 15 N(4) 45 N(3) 12 N

88.A coil has an inductance of 0.7 H and is joined in series with a resistance of 220 When an alternating e.m.f. of 220 V at 50 cps is applied to it, then the wattless component of the current in the circuit is- a. 5A b. 0.5A c. 0.7A d. 7A

The potential energy ofa particle of mass m1kg is moving alongx-axis given by U(x)=\lbrack x^2/2-x\rbrack J.If total mechanical energy of particle is 2J,then find its maximum speed.

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 approximate change in volume V of a cube of sides x meters caused by increasing the side by 1% is

For a plane electromagnetic wave propagating in x-direction, which one of the following combination gives the correct possible directions for electric field (E) and magnetic field (B) respectively?

eq wt of B(OH)3 IS

A force →F=(5^i+3^j+2^k) N is applied over a particle which displaces it from origin to the point →r=(2^i−^j) m. The work done on the particle is

In a flash type ADC, an analog input is to be converted into 4− bit digital output, then number of op-amp comparators required in ADC will be _____15

A boat's propeller has a rotational inertia of 4 kg-m2. After a constant torque is applied for 12 s, the propeller's angular speed changes from a clockwise 8 rad/s to counter-clock wise 8 rad/s. What was the torque applied to the propeller?

64.A short electric dipole of dipole moment p kept in plane of a wire of linear charge density lambda as shown. The dipole makes angle 60 with local electric field. If distance of dipole from the wire is R, then force experianced by dipole is

find the torque acting on a charged particle-q revolving around a charge Q in an elliptical orbit

A body is moving with uniform retardation covers 3km before it's speed is reduced to half of its initial value it comes to rest in another distance of

A certain transverse sinusoidal wave of wavelength 20 cm is moving in the positive x direction. The transverse velocity of the particle at x = 0 as a function of time is shown. The amplitude of the motion is:

At what height from the Earth's surface the solution due to gravity decreases by 1%

An object of size 3.0cm is placed 14cm in front of a concave lens of focal length 21cm. Describe the image produced by the lens. Whathappens if the object is moved further away from the lens?

A body of mass 5 kg is moving in a circle of radius 1m with an angular velocity of 2 radian/sec. The centripetal force is

The nearest star to our solar system is 4.29 light years away. How much is this distance in terms of parsecs? How much parallax would this star (named Alpha Centauri) show when viewed from two locations of the Earth six months apart in its orbit around the Sun ?

Can a body with zero initial velocity show 2D motion

A 250 gm grasshopper moving due south at 20 cm/s (in mid air) collides with another 150 gm grasshopper moving at a speed of 60 cm/s due north. Find the decrease in KE if they move together after collision.

In the given circuit ,which is a part of a closed circuit. find the currents i1 and i2.

Prove that net electric field at the centre of a triangle is zero if charges of magnitude q are kept at its vertices

Tap on the bubbles which give the answer as 100.

A man in a balloon, throws a stone downwards with speed of 5 m/s with tespect ot balloon. The balloon is moving upwards with a constant acceleration of 5m/s2 . Then velocity of the stone relative to the man after 2 second is

A hot air balloon is ascending at the rate 42 m/s and is 80 m above the ground when a package is dropped over the side. (a) How long does the package take to reach the ground? (b) With what speed does it hit the ground?

In a double star system of two stars of masses m and 2m, rotating about their centre of mass. Their time period of rotation about their centre of mass will be proportional to

A bent wire AB carrying a current I is placed in a region of uniform magnetic field →B. The force on the wire AB is

A 2.0 kg block is dropped from a height of 40 cm onto a spring of spring consant k=1960 N/m. Find the maximum distance the spring is compressed.

a force f=6t^2i^ +4tj^ acts on a particle of mass 3 kg. What will be the velocity of the particle at t=3 second if at t=0, the particle was at rest; 1)18i^+6J^ 2)18i^+121j^ 3)12i^ +6j^ 4)none

A certain gas takes three times as long to effuse out as helium. It's molecular mass will be

A cannon ball of mass 2 kg is fired at a target 500 m away. The 400 kg cannon recoils with a velocity of 2 ms−1. Assuming cannon ball moves with constant velocity, when will it hit the target?