50278 + Interview Questions in Physics

1.	The equation of a wave motion is given by, y=7 sin(7πt−0.4πx+π3). The ratio of wave velocity to the maximum particle velocity equal is(Assume SI units)
Answer» The equation of a wave motion is given by, $y = 7 sin (7 π t - 0.4 π x + \frac{π}{3})$ . The ratio of wave velocity to the maximum particle velocity equal is (Assume SI units)

Discussion

2.	The capacity of a condenser is 4 μF and its potential is 100 volts. The energy released while discharging of capacitor will be
Answer» The capacity of a condenser is $4 μ F$ and its potential is $100 volts$ . The energy released while discharging of capacitor will be

Discussion

3.	The water is filled upto height of 12 m in a tank having vertical sidewalls. A hole is made in one of the walls at a depth ′h′ below the waterlevel.The value of h for which the emerging stream of waterstrikes the ground at the maximum range is (in m).
Answer» The water is filled upto height of $12 m$ in a tank having vertical sidewalls. A hole is made in one of the walls at a depth $^{'} h^{'}$ below the waterlevel.The value of $h$ for which the emerging stream of waterstrikes the ground at the maximum range is $(in m)$ .

Discussion

4.	The Diesel Generator you saw usually in Family functions or industries converts ___.
Answer» The Diesel Generator you saw usually in Family functions or industries converts ___.

Discussion

5.	How many kJ of energy is spent when a current of 4 amp passes for 200 second under a potential of 115 V ?
Answer» How many kJ of energy is spent when a current of 4 amp passes for 200 second under a potential of 115 V ?

Discussion

6.	An ideal gas undergoes a quasi static, reversible process in which its molar heat capacity C remains constant. If during this process the relation of pressure P and volume V is given by PVn = constant, then n is given by (Here CP and CV are molar specific heat at constant pressure and constant volume, respectively):
Answer» An ideal gas undergoes a quasi static, reversible process in which its molar heat capacity C remains constant. If during this process the relation of pressure P and volume V is given by $P V^{n}$ = constant, then n is given by (Here $C_{P}$ and $C_{V}$ are molar specific heat at constant pressure and constant volume, respectively):

Discussion

7.	What is instantaneous current
Answer» What is instantaneous current

Discussion

8.	38. Voltage input in a circuit is V=300sin(omegat) and I is 100 sin(omegat). Average power loss is
Answer» 38. Voltage input in a circuit is V=300sin(omegat) and I is 100 sin(omegat). Average power loss is

Discussion

9.	Why Helium has max. value of Harley's constant [Kh]?
Answer» Why Helium has max. value of Harley's constant [Kh]?

Discussion

10.	Solve the previous problem if the lead piece is fastened on the top surface of the block and the block is to float with its upper surface just dipping into water.
Answer» Solve the previous problem if the lead piece is fastened on the top surface of the block and the block is to float with its upper surface just dipping into water.

Discussion

11.	The radius of a soap bubble is increased from 1√π cm to 2√πcm If the surface tension of water is 30 dynes per cm, then the work done will be
Answer» The radius of a soap bubble is increased from $\frac{1}{\sqrt{π}}$ cm to $\frac{2}{\sqrt{π}}$ cm If the surface tension of water is 30 dynes per cm, then the work done will be

11.

The radius of a soap bubble is increased from 1√π cm to 2√πcm If the surface tension of water is 30 dynes per cm, then the work done will be

Answer»

The radius of a soap bubble is increased from $\frac{1}{\sqrt{π}}$ cm to $\frac{2}{\sqrt{π}}$ cm If the surface tension of water is 30 dynes per cm, then the work done will be

Discussion

12.	A spherical ball of surface area 20 cm2 absorbs any radition that falls on it. It is suspended in a closed box maintained at 570 C. (a) Find the amoutn of radiation falling on the ball per second. (b) Find the net rate of heat flow to or from the ball at an instant when its temperature is 2000C. Stefan constant = 6.0×10−8Wm−2K−4.
Answer» A spherical ball of surface area 20 $c m^{2}$ absorbs any radition that falls on it. It is suspended in a closed box maintained at $57^{0}$ C. (a) Find the amoutn of radiation falling on the ball per second. (b) Find the net rate of heat flow to or from the ball at an instant when its temperature is $200^{0}$ C. Stefan constant = $6.0 \times 10^{- 8} W m^{- 2} K^{- 4}$ .

Discussion

13.	The gas having average speed four times as that of SO2 at same temperature is (Molar mass of SO2=64 g)
Answer» The gas having average speed four times as that of $S O_{2}$ at same temperature is (Molar mass of $S O_{2} = 64 g$ )

Discussion

14.	A 10 metric ton truck drives up a hilly road of inclination 45^° at a speed of 36 km h–1. If the coefficient of kinetic friction between the road and tyres is 0.2, calculate how fast will the same truck move down the hill with same power. 48 km/h 72 km/h 54 km/h 36 km/h
Answer» A 10 metric ton truck drives up a hilly road of inclination 45^° at a speed of 36 km h–1. If the coefficient of kinetic friction between the road and tyres is 0.2, calculate how fast will the same truck move down the hill with same power. 48 km/h 72 km/h 54 km/h 36 km/h

Discussion

15.	Hence,30. A rocket is fired vertically from the earth with an acceleration of 2g, where g is the gravitationalacceleration. On an inclined plane inside the rocket, making an angle 0 with the horizontal, a point objectof mass m is kept. The minimum coefficient of friction umin between the mass and the inclined surfaceSuch that the mass does not move is(A) tan 20(B) tan 0(C) 3 tan 0(D) 2 tan 0
Answer» Hence,30. A rocket is fired vertically from the earth with an acceleration of 2g, where g is the gravitationalacceleration. On an inclined plane inside the rocket, making an angle 0 with the horizontal, a point objectof mass m is kept. The minimum coefficient of friction umin between the mass and the inclined surfaceSuch that the mass does not move is(A) tan 20(B) tan 0(C) 3 tan 0(D) 2 tan 0

Discussion

16.	How do I apply kirchhoff's laws when there is no battery connected across the points between which we want to find the equivalent resistance or problems like that what approach should I take?
Answer» How do I apply kirchhoff's laws when there is no battery connected across the points between which we want to find the equivalent resistance or problems like that what approach should I take?

Discussion

17.	The area of the parallelogram represented by the vectors →A=2^i+3^j and →B=^i+4^j is
Answer» The area of the parallelogram represented by the vectors $\to A = 2^i + 3^j$ and $\to B =^i + 4^j$ is

Discussion

18.	If a ball is thrown vertically upward in air if air resistence is taken into consideration and t1 and t2 are time taken by it in upward motion and downward motion respctively thena t1>t2b t2>t1c t1=t2d none
Answer» If a ball is thrown vertically upward in air if air resistence is taken into consideration and t1 and t2 are time taken by it in upward motion and downward motion respctively then a t1>t2 b t2>t1 c t1=t2 d none

Discussion

19.	(a) Define electric flux. Is it a scalar or a vector quantity ? A point charge q is at a distance of d/2 directly above the centre of a square of side d, as shown in the figure. Use Gauss' law to obtain the expression for the electric flux through the square. (b) If the point charge is now moved to a distance 'd' from the centre of the square and the side of the square is doubled, explain how the electric flux will be affected.
Answer» (a) Define electric flux. Is it a scalar or a vector quantity ? A point charge q is at a distance of d/2 directly above the centre of a square of side d, as shown in the figure. Use Gauss' law to obtain the expression for the electric flux through the square. (b) If the point charge is now moved to a distance 'd' from the centre of the square and the side of the square is doubled, explain how the electric flux will be affected.

Discussion

20.	A domain in a magnet is in the form of a cube of side length 1 μm. If it contains 8×1010 atoms and each atomic dipole has a dipole moment of 9×10−24A-m2 and all of this dipoles are aligned in the same direction, then the magnetisation of the domain is:
Answer» A domain in a magnet is in the form of a cube of side length $1 μ m$ . If it contains $8 \times 10^{10}$ atoms and each atomic dipole has a dipole moment of $9 \times 10^{- 24} {A-m}^{2}$ and all of this dipoles are aligned in the same direction, then the magnetisation of the domain is:

Discussion

21.	A man climbs a light rope whose breaking strength is η times his weight (η<1). The maximum acceleration of the man so that the rope just breaks is
Answer» A man climbs a light rope whose breaking strength is $η$ times his weight $(η < 1)$ . The maximum acceleration of the man so that the rope just breaks is

Discussion

22.	One end of an elastic spring of natural length L and spring constant k is fixed to a wall and the other end is attached to a block of mass m lying on a horizontal frictionless table. The block is moved to a position A, such that the spring is compressed to half its natural length and then released. What is the velocity of the block when it reaches position B, which is at a distance 3L4 from the wall.
Answer» One end of an elastic spring of natural length $L$ and spring constant $k$ is fixed to a wall and the other end is attached to a block of mass $m$ lying on a horizontal frictionless table. The block is moved to a position A, such that the spring is compressed to half its natural length and then released. What is the velocity of the block when it reaches position B, which is at a distance $\frac{3 L}{4}$ from the wall.

Discussion

23.	Tap on the bubbles with the correct areas in square units.
Answer» Tap on the bubbles with the correct areas in square units.

Discussion

24.	If the sum of two unit vectors is a unit vector, then magnitude of difference is
Answer» If the sum of two unit vectors is a unit vector, then magnitude of difference is

Discussion

25.	In YDSE, if the separation between the slits is tripled and the distance between screen and slit plane is also tripled, then the fringe width
Answer» In YDSE, if the separation between the slits is tripled and the distance between screen and slit plane is also tripled, then the fringe width

Discussion

26.	Let O be an interior point in a rectangle ABCD such that OA=6,OB=7 and OC=8. Then the value of OD is
Answer» Let $O$ be an interior point in a rectangle $A B C D$ such that $O A = 6, O B = 7$ and $O C = 8.$ Then the value of $O D$ is

Discussion

27.	The reverse biasing in a PN junction diode
Answer» The reverse biasing in a PN junction diode

27.

The reverse biasing in a PN junction diode

Answer»

The reverse biasing in a PN junction diode

Discussion

28.	A motor driving a solid circular steel shaft transmits 40 kW of power at 500 rpm. If the diameter of the shaft is 40 mm, the maximum shear stress in the shaft is MPa.
Answer» A motor driving a solid circular steel shaft transmits 40 kW of power at 500 rpm. If the diameter of the shaft is 40 mm, the maximum shear stress in the shaft is MPa.

Discussion

29.	A body covers 200 cm in the first 2 seconds and 220 cm in the next 4 seconds. The velocity of the body at the end of the 7th second is
Answer» A body covers $200 c m$ in the first $2$ seconds and $220 c m$ in the next $4$ seconds. The velocity of the body at the end of the $7^{t h}$ second is

Discussion

30.	Define Poiseuilles Law.
Answer» Define Poiseuilles Law.

Discussion

31.	Potential difference between points A and B and the Periphery of a spherical cavity of radius R is made in a solid non conducting sphere of uniform charge density rho is
Answer» Potential difference between points A and B and the Periphery of a spherical cavity of radius R is made in a solid non conducting sphere of uniform charge density rho is

Discussion

32.	Same current is flowing in two alternating circuits. The first circuit contains only inductance and the other contains only a capacitor. If the frequency of the e.m.f. of ac is increased, the effect on the value of the current will be
Answer» Same current is flowing in two alternating circuits. The first circuit contains only inductance and the other contains only a capacitor. If the frequency of the e.m.f. of ac is increased, the effect on the value of the current will be

Discussion

33.	A ball of weight W is kept on an inclined surface as shown in the figure. The component of weight along x and y axes respectively are
Answer» A ball of weight $W$ is kept on an inclined surface as shown in the figure. The component of weight along $x$ and $y$ axes respectively are

Discussion

34.	The number of photons of wavelength 540 nm emitted per second by an electric bulb of power 100W is (taking h=6×10−34J−sec).
Answer» The number of photons of wavelength 540 nm emitted per second by an electric bulb of power 100W is (taking $h = 6 \times 10^{- 34} J - s e c)$ .

Discussion

35.	Two identical spheres A and B lie on a smooth horizontal circular groove at opposite ends of a diameter. A is projected along the groove and at the end of time t, strikes on B. If e is the coefficient of restitution, the second impact will occur after a time:
Answer» Two identical spheres A and B lie on a smooth horizontal circular groove at opposite ends of a diameter. A is projected along the groove and at the end of time $t$ , strikes on B. If $e$ is the coefficient of restitution, the second impact will occur after a time:

Discussion

36.	The value of \|→a×^i\|2+\|→a×^j\|2+\|→a×^k\|2 is
Answer» The value of $\| \to a \times^i \|^{2} + \| \to a \times^j \|^{2} + \| \to a \times^k \|^{2}$ is

Discussion

37.	Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg, (a) just after it is dropped from the window of a stationary train, (b) just after it is dropped from the window of a train running at a constant velocity of 36 km/h, (c ) just after it is dropped from the window of a train accelerating with 1 m s-2, (d) lying on the floor of a train which is accelerating with 1 m s-2, the stone being at rest relative to the train. Neglect air resistance throughout
Answer» Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg, (a) just after it is dropped from the window of a stationary train, (b) just after it is dropped from the window of a train running at a constant velocity of 36 km/h, (c ) just after it is dropped from the window of a train accelerating with 1 m s-2, (d) lying on the floor of a train which is accelerating with 1 m s-2, the stone being at rest relative to the train. Neglect air resistance throughout

Discussion

38.	20.The equation of an alternating voltage is V=220sin(Omega t+÷ 6) and the equation for current is I=10sin(Omega t+÷ 6) the impedance in ohm of the circuit is
Answer» 20.The equation of an alternating voltage is V=220sin(Omega t+÷ 6) and the equation for current is I=10sin(Omega t+÷ 6) the impedance in ohm of the circuit is

Discussion

39.	The minimum value of 15 min peak hour factor on a section of a road is
Answer» The minimum value of $15$ min peak hour factor on a section of a road is

Discussion

40.	a vehicle is moving on a road with acceleration a is equal to 20 metre per second square as shown in figure the frictional coefficient between the block m and vehicles so that the block does not fall is
Answer» a vehicle is moving on a road with acceleration a is equal to 20 metre per second square as shown in figure the frictional coefficient between the block m and vehicles so that the block does not fall is

Discussion

41.	Which of the following is an ohmic conductor?
Answer» Which of the following is an ohmic conductor?

Discussion

42.	Two long conductors, separated by a dis†an ce d carry currents l1 and l2 in the same direction. They exert a force F on each other. Now the current in one of them is increased to two times and its direction is reversed. The dis†an ce is also increased to 3d. The new value of the force between them is
Answer» Two long conductors, separated by a dis†an ce d carry currents l1 and l2 in the same direction. They exert a force F on each other. Now the current in one of them is increased to two times and its direction is reversed. The dis†an ce is also increased to 3d. The new value of the force between them is

Discussion

43.	A body is just floating on the surface of a liquid. The density of the body is same as that of the liquid. The body is slightly pushed down. What will happen to the body
Answer» A body is just floating on the surface of a liquid. The density of the body is same as that of the liquid. The body is slightly pushed down. What will happen to the body

43.

A body is just floating on the surface of a liquid. The density of the body is same as that of the liquid. The body is slightly pushed down. What will happen to the body

Answer»

A body is just floating on the surface of a liquid. The density of the body is same as that of the liquid. The body is slightly pushed down. What will happen to the body

Discussion

44.	Radiations of intensity 0.5W/m2 are striking a metal plate. The pressure on the plate is
Answer» Radiations of intensity $0.5 W / m^{2}$ are striking a metal plate. The pressure on the plate is

Discussion

45.	(i) What do you understand by the term 'acceleration due to gravity of earth'?(ii) What is the usual value of the acceleration due to gravity of earth?(iii) State the SI unit of acceleration due to gravity.
Answer» (i) What do you understand by the term 'acceleration due to gravity of earth'? (ii) What is the usual value of the acceleration due to gravity of earth? (iii) State the SI unit of acceleration due to gravity.

Discussion

46.	A proton has mass 1.6×10^{-27} kg and charge 1.6×10^{-19 c} if proton is accelerated through a potential difference of million volts,then the kinetic energy i
Answer» A proton has mass 1.6×10^{-27} kg and charge 1.6×10^{-19 c} if proton is accelerated through a potential difference of million volts,then the kinetic energy i

Discussion

47.	The electric current in a discharging R-C circuit is given by i=ioe−tRC where io , R and C are constant parameters and t is time. Let io = 2.00 A, R=6×105 Ω and C = 0.500 μ F. (a) Find the current at t = 0.3 s. (b) Find the rate of change of current at t = 0.3 s (c) Find approximately the current at t = 0.31 s.
Answer» The electric current in a discharging R-C circuit is given by $i = i_{o} e^{\frac{- t}{R C}}$ where $i_{o}$ , R and C are constant parameters and $t$ is time. Let $i_{o}$ = 2.00 A, R= $6 \times 10^{5}$ Ω and C = 0.500 $μ$ F. (a) Find the current at t = 0.3 s. (b) Find the rate of change of current at t = 0.3 s (c) Find approximately the current at t = 0.31 s.

47.

The electric current in a discharging R-C circuit is given by i=ioe−tRC where io , R and C are constant parameters and t is time. Let io = 2.00 A, R=6×105 Ω and C = 0.500 μ F. (a) Find the current at t = 0.3 s. (b) Find the rate of change of current at t = 0.3 s (c) Find approximately the current at t = 0.31 s.

Answer»

The electric current in a discharging R-C circuit is given by $i = i_{o} e^{\frac{- t}{R C}}$ where $i_{o}$ , R and C are constant parameters and $t$ is time. Let $i_{o}$ = 2.00 A, R= $6 \times 10^{5}$ Ω and C = 0.500 $μ$ F.

(a) Find the current at t = 0.3 s.

(b) Find the rate of change of current at t = 0.3 s

(c) Find approximately the current at t = 0.31 s.

Discussion

48.	A particle is found to be at rest when seen from a frame S1 and moving with a constant velocity when seen from another frame S2. Mark out the possible options.
Answer» A particle is found to be at rest when seen from a frame $S_{1}$ and moving with a constant velocity when seen from another frame $S_{2}$ . Mark out the possible options.

Discussion

49.	The image of a clock in a plane mirror shows a wrong time as 08:45. Assuming the clock did not have number markings on it, the correct time would be:
Answer» The image of a clock in a plane mirror shows a wrong time as 08:45. Assuming the clock did not have number markings on it, the correct time would be:

Discussion

50.	two block of masses m1 and m2 are connected by a massless string. Mass m1 is pulled by a horizontal forceF=60N as shown in figure.Tension in the string connecting two masses is
Answer» two block of masses m1 and m2 are connected by a massless string. Mass m1 is pulled by a horizontal forceF=60N as shown in figure.Tension in the string connecting two masses is

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

The equation of a wave motion is given by, y=7 sin(7πt−0.4πx+π3). The ratio of wave velocity to the maximum particle velocity equal is(Assume SI units)

The capacity of a condenser is 4 μF and its potential is 100 volts. The energy released while discharging of capacitor will be

The water is filled upto height of 12 m in a tank having vertical sidewalls. A hole is made in one of the walls at a depth ′h′ below the waterlevel.The value of h for which the emerging stream of waterstrikes the ground at the maximum range is (in m).

The Diesel Generator you saw usually in Family functions or industries converts ___.

How many kJ of energy is spent when a current of 4 amp passes for 200 second under a potential of 115 V ?

What is instantaneous current

38. Voltage input in a circuit is V=300sin(omegat) and I is 100 sin(omegat). Average power loss is

Why Helium has max. value of Harley's constant [Kh]?

Solve the previous problem if the lead piece is fastened on the top surface of the block and the block is to float with its upper surface just dipping into water.

The radius of a soap bubble is increased from 1√π cm to 2√πcm If the surface tension of water is 30 dynes per cm, then the work done will be

The gas having average speed four times as that of SO2 at same temperature is (Molar mass of SO2=64 g)

A 10 metric ton truck drives up a hilly road of inclination 45^° at a speed of 36 km h–1. If the coefficient of kinetic friction between the road and tyres is 0.2, calculate how fast will the same truck move down the hill with same power. 48 km/h 72 km/h 54 km/h 36 km/h

How do I apply kirchhoff's laws when there is no battery connected across the points between which we want to find the equivalent resistance or problems like that what approach should I take?

The area of the parallelogram represented by the vectors →A=2^i+3^j and →B=^i+4^j is

If a ball is thrown vertically upward in air if air resistence is taken into consideration and t1 and t2 are time taken by it in upward motion and downward motion respctively thena t1>t2b t2>t1c t1=t2d none

A domain in a magnet is in the form of a cube of side length 1 μm. If it contains 8×1010 atoms and each atomic dipole has a dipole moment of 9×10−24A-m2 and all of this dipoles are aligned in the same direction, then the magnetisation of the domain is:

A man climbs a light rope whose breaking strength is η times his weight (η&lt;1). The maximum acceleration of the man so that the rope just breaks is

Tap on the bubbles with the correct areas in square units.

If the sum of two unit vectors is a unit vector, then magnitude of difference is

In YDSE, if the separation between the slits is tripled and the distance between screen and slit plane is also tripled, then the fringe width

Let O be an interior point in a rectangle ABCD such that OA=6,OB=7 and OC=8. Then the value of OD is

The reverse biasing in a PN junction diode

A motor driving a solid circular steel shaft transmits 40 kW of power at 500 rpm. If the diameter of the shaft is 40 mm, the maximum shear stress in the shaft is MPa.

A body covers 200 cm in the first 2 seconds and 220 cm in the next 4 seconds. The velocity of the body at the end of the 7th second is

Define Poiseuilles Law.

Potential difference between points A and B and the Periphery of a spherical cavity of radius R is made in a solid non conducting sphere of uniform charge density rho is

Same current is flowing in two alternating circuits. The first circuit contains only inductance and the other contains only a capacitor. If the frequency of the e.m.f. of ac is increased, the effect on the value of the current will be

A ball of weight W is kept on an inclined surface as shown in the figure. The component of weight along x and y axes respectively are

The number of photons of wavelength 540 nm emitted per second by an electric bulb of power 100W is (taking h=6×10−34J−sec).

Two identical spheres A and B lie on a smooth horizontal circular groove at opposite ends of a diameter. A is projected along the groove and at the end of time t, strikes on B. If e is the coefficient of restitution, the second impact will occur after a time:

The value of |→a×^i|2+|→a×^j|2+|→a×^k|2 is

20.The equation of an alternating voltage is V=220sin(Omega t+÷ 6) and the equation for current is I=10sin(Omega t+÷ 6) the impedance in ohm of the circuit is

The minimum value of 15 min peak hour factor on a section of a road is

a vehicle is moving on a road with acceleration a is equal to 20 metre per second square as shown in figure the frictional coefficient between the block m and vehicles so that the block does not fall is

Which of the following is an ohmic conductor?

A body is just floating on the surface of a liquid. The density of the body is same as that of the liquid. The body is slightly pushed down. What will happen to the body

Radiations of intensity 0.5W/m2 are striking a metal plate. The pressure on the plate is

(i) What do you understand by the term 'acceleration due to gravity of earth'?(ii) What is the usual value of the acceleration due to gravity of earth?​(iii) State the SI unit of acceleration due to gravity.

A proton has mass 1.6×10^{-27} kg and charge 1.6×10^{-19 c} if proton is accelerated through a potential difference of million volts,then the kinetic energy i

A particle is found to be at rest when seen from a frame S1 and moving with a constant velocity when seen from another frame S2. Mark out the possible options.

The image of a clock in a plane mirror shows a wrong time as 08:45. Assuming the clock did not have number markings on it, the correct time would be:

two block of masses m1 and m2 are connected by a massless string. Mass m1 is pulled by a horizontal forceF=60N as shown in figure.Tension in the string connecting two masses is

A man climbs a light rope whose breaking strength is η times his weight (η<1). The maximum acceleration of the man so that the rope just breaks is

(i) What do you understand by the term 'acceleration due to gravity of earth'?(ii) What is the usual value of the acceleration due to gravity of earth?(iii) State the SI unit of acceleration due to gravity.