50278 + Interview Questions in Physics

1.	Determine the value of resistance R in the circuit shown in the figure, when the current is zero in the branch CD.
Answer» Determine the value of resistance $R$ in the circuit shown in the figure, when the current is zero in the branch $C D$ .

Discussion

2.	The time period T of oscillation of a simple pendulum depends on the following quantities :Length of the pendulum(l) Mass of the bob ( m)Acceleration due to gravity (g)Derive an expression for T using dimensional method
Answer» The time period T of oscillation of a simple pendulum depends on the following quantities : Length of the pendulum(l) Mass of the bob ( m) Acceleration due to gravity (g) Derive an expression for T using dimensional method

Discussion

3.	A body starts from rest and travels a distance s with uniform acceleration, then covers a distance 2s uniformly and finally comes to rest after moving further 5s distance under uniform retardation. The ratio of the average velocity to maximum velocity is
Answer» A body starts from rest and travels a distance $s$ with uniform acceleration, then covers a distance $2 s$ uniformly and finally comes to rest after moving further $5 s$ distance under uniform retardation. The ratio of the average velocity to maximum velocity is

Discussion

4.	108.what is relation bw work done by conservative and nonconservative force
Answer» 108.what is relation bw work done by conservative and nonconservative force

Discussion

5.	What or which activity is used to show that density ofmagnetic field is propotional to the syrength of the magnetic field
Answer» What or which activity is used to show that density ofmagnetic field is propotional to the syrength of the magnetic field

Discussion

6.	A point source of power 50π W is producing sound waves of frequency 1876 Hz. What is the pressure amplitude at a distance √330 m from the point source?[Speed of sound is 330 m/s and density of air is 1 kg/m3]
Answer» A point source of power $50 π W$ is producing sound waves of frequency $1876 Hz$ . What is the pressure amplitude at a distance $\sqrt{330} m$ from the point source? [Speed of sound is $330 m/s$ and density of air is $1 {kg/m}^{3}$ ]

Discussion

7.	The resultant unbalanced force is minimum in reciprocating engines when the part of mass of reciprocating is balanced with rotating mass
Answer» The resultant unbalanced force is minimum in reciprocating engines when the part of mass of reciprocating is balanced with rotating mass

Discussion

8.	Thermal velocity of electron is 10^5. But average velocity is zero why
Answer» Thermal velocity of electron is 10^5. But average velocity is zero why

Discussion

9.	A boy stands at the bottom of a 39.2 m tall building. He throws a ball upward which just reaches a window 19.6 m above the ground. What is the velocity of projection?
Answer» A boy stands at the bottom of a 39.2 m tall building. He throws a ball upward which just reaches a window 19.6 m above the ground. What is the velocity of projection?

Discussion

10.	Let →a=^i+^j−^k and →b=^i−^j+^k. Then the angle between →a and →b is [2 marks]
Answer» Let $\to a =^i +^j -^k$ and $\to b =^i -^j +^k .$ Then the angle between $\to a$ and $\to b$ is [2 marks]

Discussion

11.	The unit of thermal conductivity is
Answer» The unit of thermal conductivity is

Discussion

12.	Find the minimum value of force F for which the system remains at rest. Take g=10 m/s2.
Answer» Find the minimum value of force $F$ for which the system remains at rest. Take $g = 10 m / s^{2}$ .

Discussion

13.	Figure1.33 shows tracks of three charged particles in a uniformelectrostatic field. Give the signs of the three charges. Whichparticle has the highest charge to mass ratio?
Answer» Figure 1.33 shows tracks of three charged particles in a uniform electrostatic field. Give the signs of the three charges. Which particle has the highest charge to mass ratio?

13.

Figure1.33 shows tracks of three charged particles in a uniformelectrostatic field. Give the signs of the three charges. Whichparticle has the highest charge to mass ratio?

Answer»

Figure
1.33 shows tracks of three charged particles in a uniform
electrostatic field. Give the signs of the three charges. Which
particle has the highest charge to mass ratio?

Discussion

14.	A balloon has two holes. The first hole alone would have made the balloon flat in 9 mins and the second hole would have done it in 6 mins. If air leaks out at a constant rate, how long does it take for both the holes together to make the balloon flat?
Answer» A balloon has two holes. The first hole alone would have made the balloon flat in 9 mins and the second hole would have done it in 6 mins. If air leaks out at a constant rate, how long does it take for both the holes together to make the balloon flat?

Discussion

15.	what is ameter and voltmeter?
Answer» what is ameter and voltmeter?

Discussion

16.	A bullet is fired vertically upwards with velocity v from the surface of a spherical planet. When it reaches its maximum height, its acceleration due to the planet’s gravity is 14 th of its value at the surface of the planet.If the escape velocity from the planet is, vsec=v√N, then the value of N is . (Ignore energy loss due to atmosphere)
Answer» A bullet is fired vertically upwards with velocity v from the surface of a spherical planet. When it reaches its maximum height, its acceleration due to the planet’s gravity is $\frac{1}{4}$ th of its value at the surface of the planet.If the escape velocity from the planet is, $v_{s e c} = v \sqrt{N},$ then the value of N is . (Ignore energy loss due to atmosphere)

Discussion

17.	PN-junction diode works as a insulator, if connected :
Answer» PN-junction diode works as a insulator, if connected :

17.

PN-junction diode works as a insulator, if connected :

Answer»

PN-junction diode works as a insulator, if connected :

Discussion

18.	A vessel has 6g of oxygen at a pressure P and temperature 400 k. A small hole is made in it so that O2 leaks out. How much O2 leaks out if the pressure is P/2 and temperature 300 k. 1. 5g 2. 4g 3. 2g 4. 3g
Answer» A vessel has 6g of oxygen at a pressure P and temperature 400 k. A small hole is made in it so that O2 leaks out. How much O2 leaks out if the pressure is P/2 and temperature 300 k. 1. 5g 2. 4g 3. 2g 4. 3g

Discussion

19.	The elevator starts from the ground floor and goes up to the fourth floor. It drops a person and comes down to the first floor. The displacements in both these cases are:
Answer» The elevator starts from the ground floor and goes up to the fourth floor. It drops a person and comes down to the first floor. The displacements in both these cases are:

Discussion

20.	Electric charge Q is uniformly distributed on a thin semi circular ring of radius R. The potential at the centre of the ring will be
Answer» Electric charge Q is uniformly distributed on a thin semi circular ring of radius R. The potential at the centre of the ring will be

Discussion

21.	The forces P, Q & R are acting at a point in a plane. The angle between P & Q, Q & R are 150 degree and 120 degree respectively. Then for equilibrium, forces P, Q & R are in the ratio :-
Answer» The forces P, Q & R are acting at a point in a plane. The angle between P & Q, Q & R are 150 degree and 120 degree respectively. Then for equilibrium, forces P, Q & R are in the ratio :-

Discussion

22.	image is displaced by 1 m alongwith the mirror and displacing speed is also 1m/s still we are saying image's displacing speed is 2m/s.why?
Answer» image is displaced by 1 m alongwith the mirror and displacing speed is also 1m/s still we are saying image's displacing speed is 2m/s.why?

Discussion

23.	A cannon on a level plain is aimed at an angle α above the horizontal and a shell is fired with a muzzle velocity v0 towards a vertical cliff at a distance R away. Then the height from the bottom at which the shell strikes the side walls of the cliff is
Answer» A cannon on a level plain is aimed at an angle $α$ above the horizontal and a shell is fired with a muzzle velocity $v_{0}$ towards a vertical cliff at a distance R away. Then the height from the bottom at which the shell strikes the side walls of the cliff is

Discussion

24.	A car is travelling with a constant speed of 5 m/s. suddenly superman comes and starts pushing from behind providing a constant acceleration of 5 m/s2. Find the velocity of the car after 2 sec.
Answer» A car is travelling with a constant speed of 5 m/s. suddenly superman comes and starts pushing from behind providing a constant acceleration of 5 m/ $s^{2}$ . Find the velocity of the car after 2 sec.

Discussion

25.	an object and a screen are fixed at a distance 50cm apart when a converging lens is placed at two positions A and B between the object and the screen the image of object is found on the screen if the distance between A and B is 10cm then the focal length of the lens is (1) 12 cm (2) 10 cm(3) 8 cm (4) 6 cm
Answer» an object and a screen are fixed at a distance 50cm apart when a converging lens is placed at two positions A and B between the object and the screen the image of object is found on the screen if the distance between A and B is 10cm then the focal length of the lens is (1) 12 cm (2) 10 cm (3) 8 cm (4) 6 cm

Discussion

26.	The work functional of Silver and Sodium are 4.6 and 2.3 eV, respectively. The ratio of the slope of the stopping potential versus frequency plot for Silver to that of Sodium is
Answer» The work functional of Silver and Sodium are $4.6$ and $2.3 eV,$ respectively. The ratio of the slope of the stopping potential versus frequency plot for Silver to that of Sodium is

Discussion

27.	Amount of heat required to change a substance from its solid state to its liquid state at melting point is known as?
Answer» Amount of heat required to change a substance from its solid state to its liquid state at melting point is known as?

Discussion

28.	A quarter disc of radius R and mass m is rotating about an axis OO′ which is perpendicular to the plane of the disc as shown in figure. Rotational kinetic energy of the disc is
Answer» A quarter disc of radius $R$ and mass $m$ is rotating about an axis $O O^{'}$ which is perpendicular to the plane of the disc as shown in figure. Rotational kinetic energy of the disc is

Discussion

29.	How to find acceleration due to gravity
Answer» How to find acceleration due to gravity

Discussion

30.	The referacting angles of the flint and crown glass prisms are A′ and A and their refractive indices are μ′ and μ respectively. They are to be used for dispersion without deviation. The ratio of their referacting angles A′A will be :
Answer» The referacting angles of the flint and crown glass prisms are $A^{'}$ and $A$ and their refractive indices are $μ^{'}$ and $μ$ respectively. They are to be used for dispersion without deviation. The ratio of their referacting angles $\frac{A^{'}}{A}$ will be :

Discussion

31.	The total number of electrons that can be accommodated in all the orbitals having principal quantum number 2 and azimuthal quantum number 1 are:
Answer» The total number of electrons that can be accommodated in all the orbitals having principal quantum number $2$ and azimuthal quantum number $1$ are:

Discussion

32.	If angular momentum of a rigid body is incrsed by 20% then find percentage change in its rotational kinetic energy .
Answer» If angular momentum of a rigid body is incrsed by 20% then find percentage change in its rotational kinetic energy .

Discussion

33.	If G is the universal gravitational constant and ρ is the uniform density of a spherical planet. Then shortest possible period of rotation around a planet can be
Answer» If G is the universal gravitational constant and $ρ$ is the uniform density of a spherical planet. Then shortest possible period of rotation around a planet can be

Discussion

34.	A bird is flying towards north with a velocity 40 km/h and a train is moving with a velocity 40 km/h towards east. What is the velocity of the bird noted by a man in the train ?
Answer» A bird is flying towards north with a velocity $40 km/h$ and a train is moving with a velocity $40 km/h$ towards east. What is the velocity of the bird noted by a man in the train ?

Discussion

35.	Which of the following quantities is not dimensionless (1) absorptive power (2) emissive power (3) reflectivity (4) emissivit
Answer» Which of the following quantities is not dimensionless (1) absorptive power (2) emissive power (3) reflectivity (4) emissivit

Discussion

36.	A body of mass 40 gm is moving with a constant velocity of 2 cm/sec on a horizontal frictionless table. The force on the table is 39200 dyne160 dyne80 dyneZero dyne
Answer» A body of mass 40 gm is moving with a constant velocity of 2 cm/sec on a horizontal frictionless table. The force on the table is 39200 dyne 160 dyne 80 dyne Zero dyne

36.

A body of mass 40 gm is moving with a constant velocity of 2 cm/sec on a horizontal frictionless table. The force on the table is 39200 dyne160 dyne80 dyneZero dyne

Answer»

A body of mass 40 gm is moving with a constant velocity of 2 cm/sec on a horizontal frictionless table. The force on the table is

39200 dyne

160 dyne

80 dyne

Zero dyne

Discussion

37.	Which one is greater-a force of 1N or a weight of 1 kg-mass?
Answer» Which one is greater-a force of 1N or a weight of 1 kg-mass?

Discussion

38.	23. Two identical pith balls are charged by rubbing againsteach other. They are suspended from a horizontal rodthrough two strings of length 20 cm each, the separationbetween the suspension points being 5 cm. Inequilibrium, the separation between the balls is 3 cm.Find the mass of each ball and the tension in the strings.The charge on each ball has a magnitude 2.0x 108 C
Answer» 23. Two identical pith balls are charged by rubbing againsteach other. They are suspended from a horizontal rodthrough two strings of length 20 cm each, the separationbetween the suspension points being 5 cm. Inequilibrium, the separation between the balls is 3 cm.Find the mass of each ball and the tension in the strings.The charge on each ball has a magnitude 2.0x 108 C

Discussion

39.	Assume that if the shear stress in steel exceeds about 4.00×108 N/m2, the steel ruptures. If the shearing force necessary to rupture a steel bolt of diameter 1.00 cm is x×104 N, then x is [Take π=3.14 and answer upto two decimal places]
Answer» Assume that if the shear stress in steel exceeds about $4.00 \times 10^{8} {N/m}^{2}$ , the steel ruptures. If the shearing force necessary to rupture a steel bolt of diameter $1.00 cm$ is $x \times 10^{4} N$ , then $x$ is [Take $π = 3.14$ and answer upto two decimal places]

Discussion

40.	A closed organ pipe of length 10 cm has fundamental frequency equal to half the value of the second overtone of an open organ pipe. The length of the open organ pipe will be
Answer» A closed organ pipe of length $10 cm$ has fundamental frequency equal to half the value of the second overtone of an open organ pipe. The length of the open organ pipe will be

Discussion

41.	Find the magnitude of magnetic field B at the centre of a bar magnet having pole strength 3.6 Am, magnetic length 12 cm and cross-sectional area 0.90 cm2.
Answer» Find the magnitude of magnetic field $B$ at the centre of a bar magnet having pole strength $3.6 Am$ , magnetic length $12 cm$ and cross-sectional area $0.90 {cm}^{2}$ .

Discussion

42.	To maintain a rotor, at a uniform angular speed of 100 rad s−1, an engine needs to transmit a uniform torque of 100 N-m. The average power of the engine is -
Answer» To maintain a rotor, at a uniform angular speed of $100 {rad s}^{- 1}$ , an engine needs to transmit a uniform torque of $100 N-m$ . The average power of the engine is -

Discussion

43.	Three identical rods of same material are joined to form an equilateral triangle. The temperature of end A and B is maintained constant as T and T. The ratio of TC/TB will be (Assuming no loss of heat from surfaces)
Answer» Three identical rods of same material are joined to form an equilateral triangle. The temperature of end A and B is maintained constant as T and T. The ratio of T_C/T_B will be (Assuming no loss of heat from surfaces)

43.

Three identical rods of same material are joined to form an equilateral triangle. The temperature of end A and B is maintained constant as T and T. The ratio of TC/TB will be (Assuming no loss of heat from surfaces)

Answer»

Three identical rods of same material are joined to form an equilateral triangle. The temperature of end A and B is maintained constant as T and T. The ratio of T_C/T_B will be (Assuming no loss of heat from surfaces)

Discussion

44.	On a two-lane road, car A is travelling with a speed of 36 kmh−1. Two cars B and C approach car A in opposite directions with a speed of 54 kmh−1 each. At a certain instant, when the distance AB is equal to AC, both being 1 km, B decides to overtake A before C does. What minimum acceleration of car B is required to avoid an accident?
Answer» On a two-lane road, car A is travelling with a speed of $36 k m h^{- 1}$ . Two cars B and C approach car A in opposite directions with a speed of $54 k m h^{- 1}$ each. At a certain instant, when the distance AB is equal to AC, both being 1 km, B decides to overtake A before C does. What minimum acceleration of car B is required to avoid an accident?

Discussion

45.	81.Four charges each equal to Q are placed at the four corners of square & a charge q is placed at the centre of the sq.if the sys is in equilibrium then the value of q is a Q/2(1+21.414) b -Q/4(1+21.414) c Q/4(1+21.414) d. -Q/2(1+21.414) Click here to view details:
Answer» 81.Four charges each equal to Q are placed at the four corners of square & a charge q is placed at the centre of the sq.if the sys is in equilibrium then the value of q is a Q/2(1+21.414) b -Q/4(1+21.414) c Q/4(1+21.414) d. -Q/2(1+21.414) Click here to view details:

Discussion

46.	The electric field between the plates of a parallel plate capacitor when connected to a certain battery is 154 N/C. If the space is filled completely with a material of dielectric constant 2 without removing the battery, the field will become equal to
Answer» The electric field between the plates of a parallel plate capacitor when connected to a certain battery is $154 N/C$ . If the space is filled completely with a material of dielectric constant $2$ without removing the battery, the field will become equal to

Discussion

47.	44. Two identical thin rings each of radius R are co-axially placed at a distance R. If the ring have a uniform mass distribution and have masses m1 and m2 respectively, then what is the work done in moving a mass m from the centre of one ring to that of other? Is it path dependent or not?
Answer» 44. Two identical thin rings each of radius R are co-axially placed at a distance R. If the ring have a uniform mass distribution and have masses m1 and m2 respectively, then what is the work done in moving a mass m from the centre of one ring to that of other? Is it path dependent or not?

Discussion

48.	A particle moves in a circle of radius 25 cm at two revolutions per second. The acceleration of the particle in m/s2 is
Answer» A particle moves in a circle of radius $25 c m$ at two revolutions per second. The acceleration of the particle in $m / s^{2}$ is

Discussion

49.	a wire of resis†an ce 12 ohms per meter is bent to form a complete circkle of radius 10cm. the resis†an ce between its two diamertrically opposite points A and B AS SHIWN In dlfigure is
Answer» a wire of resis†an ce 12 ohms per meter is bent to form a complete circkle of radius 10cm. the resis†an ce between its two diamertrically opposite points A and B AS SHIWN In dlfigure is

Discussion

50.	61. A plane mirror is placed horizontally on level ground at a distance of 60m from the foot of the tower. Light ray from the top of the tower falling just on the edge of the mirror suffers a deviation of 90 degree. The height of the tower is?
Answer» 61. A plane mirror is placed horizontally on level ground at a distance of 60m from the foot of the tower. Light ray from the top of the tower falling just on the edge of the mirror suffers a deviation of 90 degree. The height of the tower is?

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Determine the value of resistance R in the circuit shown in the figure, when the current is zero in the branch CD.

The time period T of oscillation of a simple pendulum depends on the following quantities :Length of the pendulum(l) Mass of the bob ( m)Acceleration due to gravity (g)Derive an expression for T using dimensional method

A body starts from rest and travels a distance s with uniform acceleration, then covers a distance 2s uniformly and finally comes to rest after moving further 5s distance under uniform retardation. The ratio of the average velocity to maximum velocity is

108.what is relation bw work done by conservative and nonconservative force

What or which activity is used to show that density ofmagnetic field is propotional to the syrength of the magnetic field

A point source of power 50π W is producing sound waves of frequency 1876 Hz. What is the pressure amplitude at a distance √330 m from the point source?[Speed of sound is 330 m/s and density of air is 1 kg/m3]

The resultant unbalanced force is minimum in reciprocating engines when the part of mass of reciprocating is balanced with rotating mass

Thermal velocity of electron is 10^5. But average velocity is zero why

A boy stands at the bottom of a 39.2 m tall building. He throws a ball upward which just reaches a window 19.6 m above the ground. What is the velocity of projection?

Let →a=^i+^j−^k and →b=^i−^j+^k. Then the angle between →a and →b is [2 marks]

The unit of thermal conductivity is

Find the minimum value of force F for which the system remains at rest. Take g=10 m/s2.

Figure1.33 shows tracks of three charged particles in a uniformelectrostatic field. Give the signs of the three charges. Whichparticle has the highest charge to mass ratio?

A balloon has two holes. The first hole alone would have made the balloon flat in 9 mins and the second hole would have done it in 6 mins. If air leaks out at a constant rate, how long does it take for both the holes together to make the balloon flat?

what is ameter and voltmeter?

PN-junction diode works as a insulator, if connected :

A vessel has 6g of oxygen at a pressure P and temperature 400 k. A small hole is made in it so that O2 leaks out. How much O2 leaks out if the pressure is P/2 and temperature 300 k. 1. 5g 2. 4g 3. 2g 4. 3g

The elevator starts from the ground floor and goes up to the fourth floor. It drops a person and comes down to the first floor. The displacements in both these cases are:

Electric charge Q is uniformly distributed on a thin semi circular ring of radius R. The potential at the centre of the ring will be

The forces P, Q & R are acting at a point in a plane. The angle between P & Q, Q & R are 150 degree and 120 degree respectively. Then for equilibrium, forces P, Q & R are in the ratio :-

image is displaced by 1 m alongwith the mirror and displacing speed is also 1m/s still we are saying image's displacing speed is 2m/s.why?

A cannon on a level plain is aimed at an angle α above the horizontal and a shell is fired with a muzzle velocity v0 towards a vertical cliff at a distance R away. Then the height from the bottom at which the shell strikes the side walls of the cliff is

A car is travelling with a constant speed of 5 m/s. suddenly superman comes and starts pushing from behind providing a constant acceleration of 5 m/s2. Find the velocity of the car after 2 sec.

The work functional of Silver and Sodium are 4.6 and 2.3 eV, respectively. The ratio of the slope of the stopping potential versus frequency plot for Silver to that of Sodium is

Amount of heat required to change a substance from its solid state to its liquid state at melting point is known as?

A quarter disc of radius R and mass m is rotating about an axis OO′ which is perpendicular to the plane of the disc as shown in figure. Rotational kinetic energy of the disc is

How to find acceleration due to gravity

The referacting angles of the flint and crown glass prisms are A′ and A and their refractive indices are μ′ and μ respectively. They are to be used for dispersion without deviation. The ratio of their referacting angles A′A will be :

The total number of electrons that can be accommodated in all the orbitals having principal quantum number 2 and azimuthal quantum number 1 are:

If angular momentum of a rigid body is incrsed by 20% then find percentage change in its rotational kinetic energy .

If G is the universal gravitational constant and ρ is the uniform density of a spherical planet. Then shortest possible period of rotation around a planet can be

A bird is flying towards north with a velocity 40 km/h and a train is moving with a velocity 40 km/h towards east. What is the velocity of the bird noted by a man in the train ?

Which of the following quantities is not dimensionless (1) absorptive power (2) emissive power (3) reflectivity (4) emissivit

A body of mass 40 gm is moving with a constant velocity of 2 cm/sec on a horizontal frictionless table. The force on the table is 39200 dyne160 dyne80 dyneZero dyne

Which one is greater-a force of 1N or a weight of 1 kg-mass?

Assume that if the shear stress in steel exceeds about 4.00×108 N/m2, the steel ruptures. If the shearing force necessary to rupture a steel bolt of diameter 1.00 cm is x×104 N, then x is [Take π=3.14 and answer upto two decimal places]

A closed organ pipe of length 10 cm has fundamental frequency equal to half the value of the second overtone of an open organ pipe. The length of the open organ pipe will be

Find the magnitude of magnetic field B at the centre of a bar magnet having pole strength 3.6 Am, magnetic length 12 cm and cross-sectional area 0.90 cm2.

To maintain a rotor, at a uniform angular speed of 100 rad s−1, an engine needs to transmit a uniform torque of 100 N-m. The average power of the engine is -

Three identical rods of same material are joined to form an equilateral triangle. The temperature of end A and B is maintained constant as T and T. The ratio of TC/TB will be (Assuming no loss of heat from surfaces)

81.Four charges each equal to Q are placed at the four corners of square & a charge q is placed at the centre of the sq.if the sys is in equilibrium then the value of q is a Q/2(1+2*1.414) b -Q/4(1+2*1.414) c Q/4(1+2*1.414) d. -Q/2(1+2*1.414) Click here to view details:

The electric field between the plates of a parallel plate capacitor when connected to a certain battery is 154 N/C. If the space is filled completely with a material of dielectric constant 2 without removing the battery, the field will become equal to

44. Two identical thin rings each of radius R are co-axially placed at a distance R. If the ring have a uniform mass distribution and have masses m1 and m2 respectively, then what is the work done in moving a mass m from the centre of one ring to that of other? Is it path dependent or not?

A particle moves in a circle of radius 25 cm at two revolutions per second. The acceleration of the particle in m/s2 is

a wire of resis†an ce 12 ohms per meter is bent to form a complete circkle of radius 10cm. the resis†an ce between its two diamertrically opposite points A and B AS SHIWN In dlfigure is

61. A plane mirror is placed horizontally on level ground at a distance of 60m from the foot of the tower. Light ray from the top of the tower falling just on the edge of the mirror suffers a deviation of 90 degree. The height of the tower is?

81.Four charges each equal to Q are placed at the four corners of square & a charge q is placed at the centre of the sq.if the sys is in equilibrium then the value of q is a Q/2(1+21.414) b -Q/4(1+21.414) c Q/4(1+21.414) d. -Q/2(1+21.414) Click here to view details: