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

1.		2.
3.		4.

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 10⁵ NC^-1 per meter. What is the torque experienced by a system having a total dipole moment equal to ${10}^{-7}$ $\mathrm{C-}m$ in the negative z-direction? 

A hollow charged conductor has a tiny hole cut into its surface. The electric field in the hole is:
1. \(\left(\frac{3 \sigma}{\varepsilon_0}\right) \widehat{n}\)
2. \(\left(\frac{2 \sigma}{\varepsilon_0}\right) \widehat{n}\)
3. \(\left(\frac{\sigma}{2 \varepsilon_0}\right) \widehat{n}\)
4. \(\left(\frac{\sigma}{\varepsilon_0}\right) \widehat{n}\)

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:

             
1. \(\frac{2 q E L^2}{3 m\left(v_x\right)^2}\)
2. \(\frac{2 q E L^2}{m\left(v_x\right)^2}\)
3. \(\frac{3 q E L^2}{2 m\left(v_x\right)^2}\)
4. \(\frac{q E L^2}{2 m\left(v_x\right)^2}\)

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?
1. \(\frac{2 \lambda}{\pi \varepsilon_0 d}\)
2. \(\frac{\lambda}{2 \pi \varepsilon_0 d}\)
3. \(\frac{\lambda}{\pi \varepsilon_0 d}\)
4. \(\frac{\pi \lambda}{2 \varepsilon_0 d}\)

Sure check for the presence of electric charge is:

1. Process of induction

2. Repulsion between bodies

3. Attraction between bodies

4. Frictional force between bodies

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

1. the hollow sphere will hold more maximum charge.

2. the solid sphere will hold more maximum charge.

3. both the spheres will hold the same maximum charge.

4. both the spheres can't hold a charge.

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:

1. negatively charged.

2. positively charged.

3. uncharged.

4. Any of the above is possible

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

1. Contract

2. Dilate

3. Start oscillating

4. Collapse completely