50278 + Interview Questions in Physics

1.	A particle is projected vertically upwards with a speed 67 m/s. The distance travelled by the particle in its seventh second of its flight will be (g = 10 m/s2).
Answer» A particle is projected vertically upwards with a speed 67 m/s. The distance travelled by the particle in its seventh second of its flight will be (g = 10 m/s2).

Discussion

2.	The top of insulated cylindrical container is covered by a disc having emissivity 0.6 and thickness 1 cm. The temperature is maintained by circulating oil as shown in figure. If temperature of upper surface of disc is 127∘ Cand temperature of surrounding is 27∘ C, then the radiation loss to the surroundings will be (Take σ=173×10−8W/m2K4)
Answer» The top of insulated cylindrical container is covered by a disc having emissivity 0.6 and thickness 1 cm. The temperature is maintained by circulating oil as shown in figure. If temperature of upper surface of disc is $127^{\circ}$ Cand temperature of surrounding is $27^{\circ}$ C, then the radiation loss to the surroundings will be (Take $σ = \frac{17}{3} \times 10^{- 8} W / m^{2} K^{4}$ )

Discussion

3.	A bullet fired into a wooden block loses half of its velocity after penetrating 40 cm. It comes to rest after penetrating a further distance of
Answer» A bullet fired into a wooden block loses half of its velocity after penetrating $40 cm .$ It comes to rest after penetrating a further distance of

Discussion

4.	The unbalance spin of electron exhibita) magnetismb) spectrac) visible coloursd) allotropy
Answer» The unbalance spin of electron exhibit a) magnetism b) spectra c) visible colours d) allotropy

Discussion

5.	In the given circuit, when the switch is closed, the capacitor charges with a time constant of
Answer» In the given circuit, when the switch is closed, the capacitor charges with a time constant of

Discussion

6.	A ball is dropped from a height h above a point on an inclined plane with an angle of inclination θ. The ball makes an elastic collision with the surface and rebounds off the plane. Determine the distance from the point of first impact to the point where ball hits the plane second time.
Answer» A ball is dropped from a height $h$ above a point on an inclined plane with an angle of inclination $θ$ . The ball makes an elastic collision with the surface and rebounds off the plane. Determine the distance from the point of first impact to the point where ball hits the plane second time.

Discussion

7.	80. A particle is given vertical velocity and passes a height h two times in its journey at 4 sec and 9 sec respectively. Find the height h?
Answer» 80. A particle is given vertical velocity and passes a height h two times in its journey at 4 sec and 9 sec respectively. Find the height h?

Discussion

8.	The graph shown in the figure, represents the fall of temperature (T) of two bodies x and y having the same surface area, with time (t) due to radiation. Choose the correct relationship between emissive power (E) and absorptive power (a) of the two bodies.
Answer» The graph shown in the figure, represents the fall of temperature $(T)$ of two bodies $x$ and $y$ having the same surface area, with time $(t)$ due to radiation. Choose the correct relationship between emissive power $(E)$ and absorptive power $(a)$ of the two bodies.

Discussion

9.	Two Charges Q1 and Q2 are as shown in the figure. A third charge Q3 is moved from points A to B along a circular path. Change in potential energy of the system is
Answer» Two Charges $Q_{1}$ and $Q_{2}$ are as shown in the figure. A third charge $Q_{3}$ is moved from points A to B along a circular path. Change in potential energy of the system is

Discussion

10.	Figure shows three identical springs A, B, C. When a 4 kg mass is hung on A, it descends by 1 cm. When a 6 kg mass is hung on C, it will descend by
Answer» Figure shows three identical springs $A, B, C$ . When a $4 kg$ mass is hung on $A$ , it descends by $1 cm$ . When a $6 kg$ mass is hung on $C$ , it will descend by

Discussion

11.	find derivative of f(x)=-(x+1)/4x+7
Answer» find derivative of f(x)=-(x+1)/4x+7

Discussion

12.	When some potential difference is maintained between A and B, current I enters the network at A and leaves at B:
Answer» When some potential difference is maintained between A and B, current I enters the network at A and leaves at B:

12.

When some potential difference is maintained between A and B, current I enters the network at A and leaves at B:

Answer»

When some potential difference is maintained between A and B, current I enters the network at A and leaves at B:

Discussion

13.	State any 3 differences between Fire and Marine Insurance.
Answer» State any 3 differences between Fire and Marine Insurance.

Discussion

14.	Answer the following questions:(a) A steady current flows in a metallic conductor ofnon-uniform cross- section. Which of these quantities is constantalong the conductor: current, current density, electric field, driftspeed?(b) Is Ohm’slaw universally applicable for all conducting elements?Ifnot, give examples of elements which do not obey Ohm’s law.(c) A low voltage supply from which one needs high currentsmust have very low internal resistance. Why?(d) A high tension (HT) supply of, say, 6 kV must have a verylarge internal resistance. Why?
Answer» Answer the following questions: (a) A steady current flows in a metallic conductor of non-uniform cross- section. Which of these quantities is constant along the conductor: current, current density, electric field, drift speed? (b) Is Ohm’s law universally applicable for all conducting elements? If not, give examples of elements which do not obey Ohm’s law. (c) A low voltage supply from which one needs high currents must have very low internal resistance. Why? (d) A high tension (HT) supply of, say, 6 kV must have a very large internal resistance. Why?

14.

Answer the following questions:(a) A steady current flows in a metallic conductor ofnon-uniform cross- section. Which of these quantities is constantalong the conductor: current, current density, electric field, driftspeed?(b) Is Ohm’slaw universally applicable for all conducting elements?Ifnot, give examples of elements which do not obey Ohm’s law.(c) A low voltage supply from which one needs high currentsmust have very low internal resistance. Why?(d) A high tension (HT) supply of, say, 6 kV must have a verylarge internal resistance. Why?

Answer»

Answer the following questions:

(a) A steady current flows in a metallic conductor of
non-uniform cross- section. Which of these quantities is constant
along the conductor: current, current density, electric field, drift
speed?

(b) Is Ohm’s
law universally applicable for all conducting elements?

If
not, give examples of elements which do not obey Ohm’s law.

(c) A low voltage supply from which one needs high currents
must have very low internal resistance. Why?

(d) A high tension (HT) supply of, say, 6 kV must have a very
large internal resistance. Why?

Discussion

15.	Two identical point charges are kept at a distance d. A third identical charge is placed on the perpend bisector of the two charges at a distance x. Show that the third charge will experience maximum force when x=d/22.
Answer» Two identical point charges are kept at a distance d. A third identical charge is placed on the perpend bisector of the two charges at a distance x. Show that the third charge will experience maximum force when x=d/22.

Discussion

16.	Two point charges each having charge q are placed on the x axis at x=a and x=a.A. Plot the variation of electric field on the x axis B. Plot the variation of electric field on the y axisC. Find the position on the y axis where electric field is max
Answer» Two point charges each having charge q are placed on the x axis at x=a and x=a. A. Plot the variation of electric field on the x axis B. Plot the variation of electric field on the y axis C. Find the position on the y axis where electric field is max

Discussion

17.	2. Explain newton's first law of motion with the help of mathematical expression of newton's second law of motion
Answer» 2. Explain newton's first law of motion with the help of mathematical expression of newton's second law of motion

Discussion

18.	The linear momentum of a 3Me V photon is(1) 0.01eV sm-1(2) 0.02eV sm-1(3) 0.03eV sm-1(4) 0.04eV sm-1
Answer» The linear momentum of a 3Me V photon is (1) 0.01eV sm-1 (2) 0.02eV sm-1 (3) 0.03eV sm-1 (4) 0.04eV sm-1

Discussion

19.	The emissivity of tungsten is approximately 0.35. A tungsten sphere having 1 cm radius is suspended within a large evacuated enclosure whose walls are at 300 K. Find the power input required to maintain the sphere at a temperature of 3000 K if heat conduction along the support is neglected. σ=5.67×10−8 SI units.
Answer» The emissivity of tungsten is approximately $0.35$ . A tungsten sphere having $1 cm$ radius is suspended within a large evacuated enclosure whose walls are at $300 K$ . Find the power input required to maintain the sphere at a temperature of $3000 K$ if heat conduction along the support is neglected. $σ = 5.67 \times 10^{- 8} SI units$ .

Discussion

20.	Two trains one of length 100 m and another of length 125 m, are moving in mutually opposite directions along parallel lines, meet each other, each with speed 100 m/s. If their accelerations are 0.3 m/s2 and 0.2 m/s2 respectively, then the time they take to pass each other will be
Answer» Two trains one of length $100 m$ and another of length $125 m$ , are moving in mutually opposite directions along parallel lines, meet each other, each with speed $100 m/s$ . If their accelerations are $0.3 {m/s}^{2}$ and $0.2 {m/s}^{2}$ respectively, then the time they take to pass each other will be

Discussion

21.	A Zener diode has a contact potential of 1.5 V in the absence of biasing. It undergoes Zener breakdown for an electric field of 106 V/m at the depletion region of p−n junction. If the width of the depletion region is 2.5 μm, ______ be the reverse biased potential (in V) for the Zener breakdown to occur.
Answer» A Zener diode has a contact potential of $1.5 V$ in the absence of biasing. It undergoes Zener breakdown for an electric field of $10^{6} V/m$ at the depletion region of $p - n$ junction. If the width of the depletion region is $2.5 μ m$ , ______ be the reverse biased potential $(in V)$ for the Zener breakdown to occur.

Discussion

22.	For every action, there is an equal and opposite reaction. Do the bodies exerting action and reaction have to be in contact?
Answer» For every action, there is an equal and opposite reaction. Do the bodies exerting action and reaction have to be in contact?

Discussion

23.	A block A (5 kg) rests over another block B (3 kg) placed over a smooth horizontal surface. There is friction between A and B. A horizontal force F1 gradually increasing from zero to a maximum is applied to A so that the blocks move together without relative motion. Instead of this another horizontal force F2, gradually increasing from zero to a maximum is applied to B so that the blocks move together without relative motion. Then
Answer» A block $A (5 kg)$ rests over another block $B (3 kg)$ placed over a smooth horizontal surface. There is friction between $A$ and $B$ . A horizontal force $F_{1}$ gradually increasing from zero to a maximum is applied to $A$ so that the blocks move together without relative motion. Instead of this another horizontal force $F_{2}$ , gradually increasing from zero to a maximum is applied to $B$ so that the blocks move together without relative motion. Then

Discussion

24.	A curved road of radius 50 m is banked at correct angle for a given speed. If the speed is to be doubled keeping the same banking angle, the radius of curvature of the road should be changed to
Answer» A curved road of radius $50 m$ is banked at correct angle for a given speed. If the speed is to be doubled keeping the same banking angle, the radius of curvature of the road should be changed to

Discussion

25.	Comment on the correctness of the following two statements Statement I => The electrical field calculated by Gauss’s law is the field only due to the charges inside the Gaussian surface. Statement II => The flux of the electric field through a closed surface due to all the charges (inside and outside the surface), is equal to the flux only due to the charges enclosed by the surface.
Answer» Comment on the correctness of the following two statements Statement I => The electrical field calculated by Gauss’s law is the field only due to the charges inside the Gaussian surface. Statement II => The flux of the electric field through a closed surface due to all the charges (inside and outside the surface), is equal to the flux only due to the charges enclosed by the surface.

25.

Comment on the correctness of the following two statements Statement I => The electrical field calculated by Gauss’s law is the field only due to the charges inside the Gaussian surface. Statement II => The flux of the electric field through a closed surface due to all the charges (inside and outside the surface), is equal to the flux only due to the charges enclosed by the surface.

Answer»

Comment on the correctness of the following two statements

Statement I => The electrical field calculated by Gauss’s law is the field only due to the charges inside the Gaussian surface.

Statement II => The flux of the electric field through a closed surface due to all the charges (inside and outside the surface), is equal to the flux only due to the charges enclosed by the surface.

Discussion

26.	a dipole with an electric moment p is located at a dis†an ce r from a long thread charged uniformly with linear charge density λ . find force acting on dipole if vector p is oriented along the thread
Answer» a dipole with an electric moment p is located at a dis†an ce r from a long thread charged uniformly with linear charge density λ . find force acting on dipole if vector p is oriented along the thread

Discussion

27.	Two resis†an ces R_1 and R_2 each of 100 ohm are connected with potential source of 40V between A and B. If resis†an ce of voltmeter is 200 ohm, reading of the voltmeter is
Answer» Two resis†an ces R_1 and R_2 each of 100 ohm are connected with potential source of 40V between A and B. If resis†an ce of voltmeter is 200 ohm, reading of the voltmeter is

Discussion

28.	Two metal wires of identical dimensions are connected in series. If δ1 and δ2 are the conductivities of the metal wires respectively, the effective conductivity of the combination is
Answer» Two metal wires of identical dimensions are connected in series. If $δ_{1}$ and $δ_{2}$ are the conductivities of the metal wires respectively, the effective conductivity of the combination is

Discussion

29.	A wire is bent in the form of a circular arc of radius ‘r’ with a straight portion AB. If the current in the wire is I, find magnetic induction at O.
Answer» A wire is bent in the form of a circular arc of radius ‘r’ with a straight portion AB. If the current in the wire is I, find magnetic induction at O.

Discussion

30.	Light of wavelength 488 nm is produced by an Argon laser, which is used in the photoelectric effect. When light from this spectral line is incident on the emitter, the stopping (cut-off) potential of photoelectrons is 0.38 V. Find the work function of the material from which the emitter is made.
Answer» Light of wavelength 488 nm is produced by an Argon laser, which is used in the photoelectric effect. When light from this spectral line is incident on the emitter, the stopping (cut-off) potential of photoelectrons is 0.38 V. Find the work function of the material from which the emitter is made.

Discussion

31.	What is the internal mechanism in a cell that keeps its voltage constant?
Answer» What is the internal mechanism in a cell that keeps its voltage constant?

Discussion

32.	A particle of mass m has half the kinetic energy of another particle of mass m2. The ratio of the speeds of the lighter and heavier particles is
Answer» A particle of mass $m$ has half the kinetic energy of another particle of mass $\frac{m}{2}$ . The ratio of the speeds of the lighter and heavier particles is

Discussion

33.	The figure shows, at time t=0 second, a rectangular and triangular pulse on a uniform wire, approaching each other. The pulse speed (of rectangular and triangular pulse) is 0.5 cm/s. The resultant pulse at t=2 second is,
Answer» The figure shows, at time $t = 0 second$ , a rectangular and triangular pulse on a uniform wire, approaching each other. The pulse speed (of rectangular and triangular pulse) is $0.5 cm/s$ . The resultant pulse at $t = 2 second$ is,

Discussion

34.	The figure below shows a pin jointed frame.The algebric sum of forces in members, BE, CE and CD is ______kN.[Take tension force as positive and compression force as negative]-23.82
Answer» The figure below shows a pin jointed frame. The algebric sum of forces in members, BE, CE and CD is ______kN. [Take tension force as positive and compression force as negative] -23.82

Discussion

35.	In uniform electric field E=10 N/C as shown in figure. The potential difference, VA−VB and VB−VC respectively
Answer» In uniform electric field $E = 10 N/C$ as shown in figure. The potential difference, $V_{A} - V_{B}$ and $V_{B} - V_{C}$ respectively

Discussion

36.	The increasing order of the ionic radii of the given isoelectronic species is:
Answer» The increasing order of the ionic radii of the given isoelectronic species is:

Discussion

37.	What is the difference b/w drift velocity and random motion of electrons. how electron change their velocities when electric field is applied?
Answer» What is the difference b/w drift velocity and random motion of electrons. how electron change their velocities when electric field is applied?

Discussion

38.	The velocity displacement graph of a particle moving along a straight line is shownThe most suitable acceleration -displacement (a−x) graph will be
Answer» The velocity displacement graph of a particle moving along a straight line is shown The most suitable acceleration -displacement $(a - x)$ graph will be

Discussion

39.	Two coaxial solenoids are made by winding thin insulated wire over a pipe of cross-sectional area A=10cm2 and length = 20 cm. If one of the solenoids has 300 turns and the other 400 turns, their mutual inductance is
Answer» Two coaxial solenoids are made by winding thin insulated wire over a pipe of cross-sectional area $A = 10 c m^{2}$ and length = 20 cm. If one of the solenoids has 300 turns and the other 400 turns, their mutual inductance is

Discussion

40.	Explain Coulomb's law.
Answer» Explain Coulomb's law.

Discussion

41.	During an experiment, an ideal gas is found to obey a law VP2= constant. The gas is initially at temperature T and volume V. When it expands to volume 2V, the resulting temperature will be
Answer» During an experiment, an ideal gas is found to obey a law $V P^{2} =$ constant. The gas is initially at temperature $T$ and volume $V$ . When it expands to volume $2 V$ , the resulting temperature will be

Discussion

42.	What is sinusoid?
Answer» What is sinusoid?

Discussion

43.	If a dipole of dipole moment p^ i is placed at point (0, y) anda point charge at the origin of a co-ordinate system, netelectric field at point (x, x + y) vanishes. If x and y both arepositive, the co-ordinate y is equal to
Answer» If a dipole of dipole moment p^ i is placed at point (0, y) anda point charge at the origin of a co-ordinate system, netelectric field at point (x, x + y) vanishes. If x and y both arepositive, the co-ordinate y is equal to

Discussion

44.	One reversible heat engine operates between 900 K and T2 K, and another reversible heat engine operates between T2 K and 400 K. If both the engine have the same efficiency, then the temperature T2 must be equal to
Answer» One reversible heat engine operates between $900 K$ and $T_{2} K$ , and another reversible heat engine operates between $T_{2} K$ and $400 K$ . If both the engine have the same efficiency, then the temperature $T_{2}$ must be equal to

Discussion

45.	A fish inside a river will appear at a _________ depth to an observer looking from the ground.
Answer» A fish inside a river will appear at a _________ depth to an observer looking from the ground.

Discussion

46.	if velocity is speed in a particular direction and speed is how fast or slow an object is moving then why the formula of speed and velocity diff
Answer» if velocity is speed in a particular direction and speed is how fast or slow an object is moving then why the formula of speed and velocity diff

Discussion

47.	The graph AB shown in figure is a plot of temperature of a body in degree Celsius and degree Fahrenheit. Then
Answer» The graph AB shown in figure is a plot of temperature of a body in degree Celsius and degree Fahrenheit. Then

Discussion

48.	If linear density of a rod of length 3 m varies as λ=1+x, then the position of the centre of mass of the rod is
Answer» If linear density of a rod of length 3 m varies as $λ = 1 + x$ , then the position of the centre of mass of the rod is

Discussion

49.	A satellite in a force free space sweeps stationary interplanetary dust at a rate dMdt=αv, where M is the mass and v is the velocity of the satellite and α is a constant. The acceleration of the satellite is
Answer» A satellite in a force free space sweeps stationary interplanetary dust at a rate $\frac{d M}{d t} = α v$ , where M is the mass and v is the velocity of the satellite and $α$ is a constant. The acceleration of the satellite is

Discussion

50.	Three point charges are placed at the vertices of a square of diagonal 4 m as shown in figure.What will be the net force experienced by a charge −q placed at centre of a square ?
Answer» Three point charges are placed at the vertices of a square of diagonal $4 m$ as shown in figure. What will be the net force experienced by a charge $- q$ placed at centre of a square ?

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A particle is projected vertically upwards with a speed 67 m/s. The distance travelled by the particle in its seventh second of its flight will be (g = 10 m/s2).

A bullet fired into a wooden block loses half of its velocity after penetrating 40 cm. It comes to rest after penetrating a further distance of

The unbalance spin of electron exhibita) magnetismb) spectrac) visible coloursd) allotropy

In the given circuit, when the switch is closed, the capacitor charges with a time constant of

A ball is dropped from a height h above a point on an inclined plane with an angle of inclination θ. The ball makes an elastic collision with the surface and rebounds off the plane. Determine the distance from the point of first impact to the point where ball hits the plane second time.

80. A particle is given vertical velocity and passes a height h two times in its journey at 4 sec and 9 sec respectively. Find the height h?

The graph shown in the figure, represents the fall of temperature (T) of two bodies x and y having the same surface area, with time (t) due to radiation. Choose the correct relationship between emissive power (E) and absorptive power (a) of the two bodies.

Two Charges Q1 and Q2 are as shown in the figure. A third charge Q3 is moved from points A to B along a circular path. Change in potential energy of the system is

Figure shows three identical springs A, B, C. When a 4 kg mass is hung on A, it descends by 1 cm. When a 6 kg mass is hung on C, it will descend by

find derivative of f(x)=-(x+1)/4x+7

When some potential difference is maintained between A and B, current I enters the network at A and leaves at B:

State any 3 differences between Fire and Marine Insurance.

Two identical point charges are kept at a distance d. A third identical charge is placed on the perpend bisector of the two charges at a distance x. Show that the third charge will experience maximum force when x=d/22.

Two point charges each having charge q are placed on the x axis at x=a and x=a.A. Plot the variation of electric field on the x axis B. Plot the variation of electric field on the y axisC. Find the position on the y axis where electric field is max

2. Explain newton's first law of motion with the help of mathematical expression of newton's second law of motion

The linear momentum of a 3Me V photon is(1) 0.01eV sm-1(2) 0.02eV sm-1(3) 0.03eV sm-1(4) 0.04eV sm-1

Two trains one of length 100 m and another of length 125 m, are moving in mutually opposite directions along parallel lines, meet each other, each with speed 100 m/s. If their accelerations are 0.3 m/s2 and 0.2 m/s2 respectively, then the time they take to pass each other will be

For every action, there is an equal and opposite reaction. Do the bodies exerting action and reaction have to be in contact?

A curved road of radius 50 m is banked at correct angle for a given speed. If the speed is to be doubled keeping the same banking angle, the radius of curvature of the road should be changed to

a dipole with an electric moment p is located at a dis†an ce r from a long thread charged uniformly with linear charge density λ . find force acting on dipole if vector p is oriented along the thread

Two resis†an ces R_1 and R_2 each of 100 ohm are connected with potential source of 40V between A and B. If resis†an ce of voltmeter is 200 ohm, reading of the voltmeter is

Two metal wires of identical dimensions are connected in series. If δ1 and δ2 are the conductivities of the metal wires respectively, the effective conductivity of the combination is

A wire is bent in the form of a circular arc of radius ‘r’ with a straight portion AB. If the current in the wire is I, find magnetic induction at O.

Light of wavelength 488 nm is produced by an Argon laser, which is used in the photoelectric effect. When light from this spectral line is incident on the emitter, the stopping (cut-off) potential of photoelectrons is 0.38 V. Find the work function of the material from which the emitter is made.

What is the internal mechanism in a cell that keeps its voltage constant?

A particle of mass m has half the kinetic energy of another particle of mass m2. The ratio of the speeds of the lighter and heavier particles is

The figure shows, at time t=0 second, a rectangular and triangular pulse on a uniform wire, approaching each other. The pulse speed (of rectangular and triangular pulse) is 0.5 cm/s. The resultant pulse at t=2 second is,

The figure below shows a pin jointed frame.The algebric sum of forces in members, BE, CE and CD is ______kN.[Take tension force as positive and compression force as negative]-23.82

In uniform electric field E=10 N/C as shown in figure. The potential difference, VA−VB and VB−VC respectively

The increasing order of the ionic radii of the given isoelectronic species is:

What is the difference b/w drift velocity and random motion of electrons. how electron change their velocities when electric field is applied?

The velocity displacement graph of a particle moving along a straight line is shownThe most suitable acceleration -displacement (a−x) graph will be

Two coaxial solenoids are made by winding thin insulated wire over a pipe of cross-sectional area A=10cm2 and length = 20 cm. If one of the solenoids has 300 turns and the other 400 turns, their mutual inductance is

Explain Coulomb's law.

During an experiment, an ideal gas is found to obey a law VP2= constant. The gas is initially at temperature T and volume V. When it expands to volume 2V, the resulting temperature will be

What is sinusoid?

If a dipole of dipole moment p^ i is placed at point (0, y) anda point charge at the origin of a co-ordinate system, netelectric field at point (x, x + y) vanishes. If x and y both arepositive, the co-ordinate y is equal to

One reversible heat engine operates between 900 K and T2 K, and another reversible heat engine operates between T2 K and 400 K. If both the engine have the same efficiency, then the temperature T2 must be equal to

A fish inside a river will appear at a _________ depth to an observer looking from the ground.

if velocity is speed in a particular direction and speed is how fast or slow an object is moving then why the formula of speed and velocity diff

The graph AB shown in figure is a plot of temperature of a body in degree Celsius and degree Fahrenheit. Then

If linear density of a rod of length 3 m varies as λ=1+x, then the position of the centre of mass of the rod is

A satellite in a force free space sweeps stationary interplanetary dust at a rate dMdt=αv, where M is the mass and v is the velocity of the satellite and α is a constant. The acceleration of the satellite is

Three point charges are placed at the vertices of a square of diagonal 4 m as shown in figure.What will be the net force experienced by a charge −q placed at centre of a square ?