Principle of Superposition

Q. Four point charges qA = 2 μC, qB = –5 μC, qC = 2 μC, and qD = –5 μC arelocated at the corners of a square ABCD of side 10 cm. What is the force on a charge of 1 μC placed at the centre of the square?

Q.

What is electrostatic force?

Q.

Which of the following charge is not possible on a body?

(1) 1.6 x ${10}^{-18}$ C

(2) 1.6 x ${10}^{-20}$ C

(3) 1.6 x ${10}^{-14}$ C

(4) 1.6 x ${10}^{-5}$ C

Q.

Three equal charges, $2.0\times {10}^{-6}C$ Each are held fixed at the three corners of an equilateral triangle of side 5 cm. Find the coulomb forc eexperiencd by one of the charges due to the rest two

Q. Two similar spheres having +q and -q charge are kept at a certain distance. F force acts between the two. If in the middle of two spheres, another similar sphere having +q charge is kept, then it experiences a force whose magnitude and direction are

1. Zero having no direction
2. 8F towards +q charge
3. 8F towards -q charge
4. 4F towards +q charge

Q. The spherical planets have the same mass but densities in the ratio $1:8$. for these planets, the

1. acceleration due to gravity will be in the ratio $4:1$
2. acceleration due to gravity will be in the ratio $1:4$
3. escape velocities from their surfaces will be in the ratio $\sqrt{2}:1$
4. escape velocities from their surfaces will be in the ratio $1:\sqrt{2}$

Q. A square of side 2cm has 4 points charges at the corner of square, A=-2Q B=+2Q C=-Q D=+Q.Find the magnitude and direction of electric field at the centre O of the square, ifQ is0.02μ

Q. Three charges -q₁, + q₂ and -q₃ are placed as shown in the figure. The x-component of the force on -q₁ is proportional to

1. 
2. 
3. 
4. 

Q.

Two small spheres, each of mass $0.1\text{gm}$ and carrying same charge of ${10}^{-9}\text{C}$ are suspended by threads of equal length from the same point. If the distance between the centers of the sphere is $3\text{cm}$, then find out the angle made by the thread with the vertical. $\left(g=10{\text{m/s}}^2\right)$ and $\left({\tan }^{-1}\frac{1}{100}=0.6^{\circ }\right)$

Q. Two equal point charges A and B are R distance apart. A third point charge placed on the perpendicular bisector at a distance d from the centre will experience maximum electrostatic force then find the value of d

Q.

How do you find the electric field between two plates?

Q. Six charges, three positive and three negative of equal magnitude are to be placed at the vertices of a regular hexagon such that the electric field at O is double the electric field when only one positive charge of same magnitude is placed at R. Which of the following arrangements of charges is possible for P, Q, R, S, T and U respectively

1. +, -, +, -, +, -
2. +, +, -, +, -, -
3. -, +, +, -, +, -
4. +, -, +, -, -, +

Q.

Two identical pith balls, each carrying a charge q, are suspended from a common point by two strings of equal length l. Find the mass of each ball if the angle between the strings is $2\theta$ in equilibrium.

Q. when velocity of a relativistic charged particle increases its specific charge will increase or decrease and how

Q.

Why cannot we obtain interference using two independent sources of light ?

Q.

Three charges each of magnitude q are placed at the corners of an equilateral triangle, the electrostatic force on the charge placed at the center is: (each side of triangle is L)

1. $\frac{1}{4\pi {\epsilon }_O}\frac{q^2}{L^2}$
   
2. $\frac{1}{4\pi {\epsilon }_O}\frac{3q^2}{L^2}$ \
   
3. $\frac{1}{12\pi {\epsilon }_O}\frac{q^2}{L^2}$
4. Zero

Q. $ABC$ is a right angled triangle in which $AB=3\text{cm}$ and $BC=4\text{cm}$. And $\angle ABC=\pi /2.$ The three charges $+15,+12$ and $-20\text{e.s.u}$ are placed respectively on $A,B$ and $C$. The force acting on $B$ is

1. $125$ dynes
2. $35$ dynes
3. $25$ dynes
4. Zero

Q.

What is the value of g at the center of the earth?

Q.

Four particles of masses m, 2m, 3m and 4m are kept in sequence at the corners of a square of side a. The magnitude of gravitational force acting on a particle of mass m placed at the centre of the square will be

1. 

2. 

3. 

4. 

Q.

Four particles having masses, m, 2m, 3m and 4m are placed at the four corners of a square of edge a. Find the gravitational force acting on a particle of mass m placed at the centre.

Q. Four point charges, each of +q, are rigidly fixed at the four corners of a square planar soap film of side a. The surface tension of the soap film is $\eta$. The system of charges and planar film are in equilibrium, and $a=k{\left[\frac{q^2}{\gamma }\right]}^{1/N}$, where k is a constant. Find the value of N. ___

Q. Waves from two sources superpose on each other at a particular point, amplitude and frequency of both the waves are equal. The ratio of intensities when both waves reach in the same phase and when they reach with the phase difference of ${90}^{\circ }$ will be

1. $1:1$
2. $\sqrt{2}:1$
3. $4:1$
4. $2:1$

Q.

Four point charges $q_A=2\mu C,q_B=-5\mu C,q_C=2\mu C,and{q}_D=-5\mu C$ are located at the corners of a square ABCD of side 10cm. What is the force on a charge of $1\mu C$ placed at the centre of the square?

Q. An amplitude modulated wave is represented by the equation $V_m=5(1+0.6\cos 6280t)\sin (211\times {10}^{4}t)\text{V}$. The minimum and maximum amplitudes of the amplitude modulated wave are, respectively :

1. $\frac{3}{2}\text{V},5\text{V}$
2. $2\text{V},8\text{V}$
3. $5\text{V},8\text{V}$
4. $3\text{V},5\text{V}$

Q. Two similar coils of radius $R$ are lying concentrically with their planes at right angles to each other, if the current through them are $2I$ and $4I$ respectively, then net magnetic induction at the centre is

1. $\frac{\sqrt{5}{\mu }_{0}I}{R}$
2. $\frac{\sqrt{5}{\mu }_{0}I}{2R}$
3. $\frac{{\mu }_{0}I}{R}$
4. $\frac{{\mu }_{0}I}{2R}$

Q. A uniform string of length $20m$ is suspended from a rigid support. A short wave pulse is introduced at its lowest end. It starts moving up the string. The time taken to reach the support is (take $g=10m{s}^{-2}$)

1. $2\pi \sqrt{2}s$
2. $2s$
3. $2\sqrt{2}s$
4. $\sqrt{2}s$

Q. A charge $q$ is placed at the centre of the line joining two equal charges $Q$. The system of three charges will be in equilibrium if $q$ is equal to:

1. $-\frac{Q}{4}$
2. $-\frac{Q}{2}$
3. $+\frac{Q}{4}$
4. $+\frac{Q}{2}$

Q.

How do you calculate the electric field between two charges?

Q.

Energy associated with a moving charge is due to

1. Electric field

2. Magnetic field

3. Both $\left(a\right)$ and $\left(b\right)$

4. None of these

Q. A test particle is moving in circular orbit in the gravitational field produced by a mass density $\rho \left(r\right)=\frac{K}{r^2}.$ Identify the correct relation between the radius $R$ of the particle's orbit and its period $T$-

1. $\frac{T}{R^2}$ is a constant
2. $TR$ is a constant
3. $\frac{T}{R}$ is a constant
4. $\frac{T^2}{R^3}$ is a constant