Five balls marked a to e are suspended using separate threads. Pairs (b, c) and (d, e) show electrostatic repulsion while pairs (a, b), (c, e) and (a, e) show electrostatic attraction. The ball marked a must be:

When a plastic rod rubbed with wool is brought near the knob of a negatively charged gold-leaf electroscope, the gold leaves:

Which of the following is not true about the electric charge?

Which of the following processes involves the principle of electrostatic induction?

When a conducting soap bubble is negatively charged then:

Coulomb's law is analogous to:

Two-point charges Q₁ and Q₂ exert a force F on each other when kept at a certain distance apart. If the charge on each particle is halved and the distance between the two particles is doubled, then the new force between the two particles would be:

A point charge of 2.0 μC is at the center of a cubic Gaussian surface 9.0 cm on edge. What is the net electric flux through the surface?

$$\begin{gathered} \left(1\right) 2.26\times {10}^5 N m^2 C^{-1} \\ \left(2\right) 2.09\times {10}^5 N m^2 C^{-1} \\ \left(3\right) 4.33\times {10}^5 N m^2 C^{-1} \\ \left(4\right) 4.71\times {10}^5 N m^2 C^{-1} \end{gathered}$$

A point charge causes an electric flux of $-1.0\times {10}^3 N m^2/C$ to pass through a spherical Gaussian surface of 10.0 cm radius centered on the charge. If the radius of the Gaussian surface were doubled, how much flux would pass through the surface?

$$\begin{gathered} \left(1\right) -2.0\times {10}^3 N m^2/C \\ \left(2\right) -1.0\times {10}^3 N m^2/C \\ \left(3\right) 2.0\times {10}^3 N m^2/C \\ \left(4\right) 0 \end{gathered}$$

A conducting sphere of radius 10 cm has an unknown charge. If the electric field, 20 cm from the centre of the sphere is 1.5×10 ³ N/C and points radially inward, what is the net charge on the sphere?

A uniformly charged conducting sphere of 2.4 m diameter has a surface charge density of $80.0 \mu C/m^2$. The charge on the sphere is:

$$\begin{gathered} \left(1\right) 2.077\times {10}^{-3} C \\ \left(2\right) 2.453\times {10}^{-3} C \\ \left(3\right) 1.447\times {10}^{-3} C \\ \left(4\right) 3.461\times {10}^{-3} C \end{gathered}$$

An infinite line charge produces a field of 9×10 ⁴ N/C at a distance of 2 cm. The linear charge density is:

$$\begin{gathered} \left(1\right) 0.1 \mu C/m \\ \left(2\right) 100 \mu C/m \\ \left(3\right) 1.0 \mu C/m \\ \left(4\right) 10 \mu C/m \end{gathered}$$

Two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of opposite signs and of magnitude 17.0 x 10^-22 C/m². The electric field between the plates is: 

$$\begin{gathered} \left(1\right) 0.96\times {10}^{-10} N/C \\ \left(2\right) 1.92\times {10}^{-10} N/C \\ \left(3\right) 0 \\ \left(4\right) 3.84\times {10}^{-10} N/C \end{gathered}$$

Two equally charged identical small balls kept at some fixed distance apart exert a repulsive force F on each other. A similar uncharged ball, after touching one of them is placed at the mid-point of the line joining the two balls. The force experienced by the third ball is: 

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 a maximum electrostatic force when:

A charged gold leaf electroscope has its leaves apart by a certain amount of having enclosed air. When the electroscope is subjected to X-rays, then the leaves:

Two equal positive charges Q are fixed at points (a, 0) and (-a, 0) on the x-axis. An opposite charge -q at rest is released from point (0, a) on the y-axis. The charge -q will

Four charges each equal to Q are placed at the four corners of a square and a charge q is placed at the centre of the square. If the system is in equilibrium then the value of q is:

An oil drop of 12 excess electrons is held stationary under a constant electric field of $2.55\times {10}^{-4} N C^{-1}$. The density of the oil is $1.26 g c{m}^{-3}$. The radius of the drop is:

$$\begin{gathered} \left(1\right) 9.82\times {10}^{-4} mm \\ \left(2\right) 9.82\times {10}^{-7} mm \\ \left(3\right) 8.92\times {10}^{-4} mm \\ \left(4\right) 8.92\times {10}^{-7} mm \end{gathered}$$ 

Which among the curves shown in the figure represents electrostatic field lines?

In a certain region of space, the electric field is along the z-direction throughout. The magnitude of the electric field is, however, not constant but increases uniformly along the positive z-direction, at the rate of ${10}^5 N C^{-1}$ per meter. What is the torque experienced by a system having a total dipole moment equal to ${10}^{-7} C m$ in the negative z-direction?

A hollow charged conductor has a tiny hole cut into its surface. The electric field in the hole is:

$$\begin{gathered} \left(1\right) \left(\frac{3\sigma }{{\epsilon }_0}\right) \hat{n} \\ \left(2\right) \left(\frac{2\sigma }{{\epsilon }_0}\right) \hat{n} \\ \left(3\right) \left(\frac{\sigma }{2{\epsilon }_0}\right) \hat{n} \\ \left(4\right) \left(\frac{\sigma }{{\epsilon }_0}\right) \hat{n} \end{gathered}$$

A particle of mass m and charge (–q) enters the region between the two charged plates initially moving along the x-axis with speed $v_x$ (as shown in the figure). The length of the plate is L and a uniform electric field E is maintained between the plates. The vertical deflection of the particle at the far edge of the plate is:

$$\begin{gathered} \left(1\right) \frac{2qE{L}^2}{3m{\left(v_x\right)}^2} \\ \left(2\right) \frac{2qE{L}^2}{m{\left(v_x\right)}^2} \\ \left(3\right) \frac{3qE{L}^2}{2m{\left(v_x\right)}^2} \\ \left(4\right) \frac{qE{L}^2}{2m{\left(v_x\right)}^2} \end{gathered}$$

A spherical conducting shell of inner radius $r_1$ and outer radius $r_2$ has a charge Q. A charge q is placed at the center of the shell. The surface charge density on the outer surfaces of the shell is:
 

A long charged cylinder of linear charged density is surrounded by a hollow co-axial conducting cylinder. What is the electric field in the space between the two cylinders at distance d from the common axis?

$$\begin{gathered} \left(1\right) \frac{2\lambda }{\pi {\epsilon }_{0}d} \\ \left(2\right) \frac{\lambda }{2\pi {\epsilon }_{0}d} \\ \left(3\right) \frac{\lambda }{\pi {\epsilon }_{0}d} \\ \left(4\right) \frac{\pi \lambda }{2{\epsilon }_{0}d} \end{gathered}$$

Sure check for the presence of electric charge is:

If a solid and a hollow conducting sphere have the same radii then:

A charge q is to be distributed on two conducting spheres. What should be the value of the charges on the spheres so that the repulsive force between them is maximum when they are placed at a fixed distance from each other in the air?

A point charge q₁ exerts an electric force on a second point charge q₂. If third charge q₃ is brought near, the electric force of q₁ exerted on q_2:

Three charges +4q, Q and q are placed in a straight line of length l at points 0, $\frac{\mathrm{l}}{2}$ and l distance away from one end respectively. What should be Q in order to make the net force on q to be zero?