Which of the following is incorrect about the electrostatic field lines?
1. These can be never be closed curves
2. On a conducting surface, the lines are perpendicular
3. They can pass through a conductor
4. If the lines are equispaced and parallel to one another, then the field is uniform
Given below are two statements:
| Statement I: | A sensitive electric equipment can be saved from the electric field by enclosing it inside a metallic shell. |
| Statement II: | Electric field inside a metallic shell is zero provided that the shell does not enclose any charge. |
| 1. | Statement I is false but Statement II is true. |
| 2. | Both Statement I and Statement II are true. |
| 3. | Both Statement I and Statement II are false. |
| 4. | Statement I is true but Statement II is false. |
A thin, metallic spherical shell contains a charge Q on it. A point charge q is placed at the centre of the shell and another charge q1 is placed outside it as shown in the figure. All the three charges are positive. The force on the central charge due to the shell is:
1. towards left
2. towards right
3. upward
4. zero
An uncharged aluminium block has a cavity within it. The block is placed in a region permeated by a uniform electric field which is directed upwards. Which of the following is a correct statement describing conditions in the interior of the block's cavity?
1. The electric field in the cavity is directed upwards
2. The electric field in the cavity is directed downwards
3. There is no electric field in the cavity
4. The electric field in the cavity is of varying magnitude and is zero at the exact center.
The electrostatic potential on the surface of a charged conducting sphere is \(100~\text{V}\). Two statements are made in this regard.
| Statement I: | At any point inside the sphere, electric intensity is zero. |
| Statement II: | At any point inside the sphere, the electrostatic potential is \(100~\text{V}\). |
Which of the following is a correct statement?
| 1. | Statement I is true but Statement II is false. |
| 2. | Both Statement I and Statement II are false. |
| 3. | Statement I is true, Statement II is also true and Statement I is the cause of Statement II. |
| 4. | Statement I is true, Statement II is also true but the statements are independent. |
Which one of the following is wrong?
| 1. | A comb run through one’s dry hair attracts small bits of paper. |
| 2. | Ordinary rubber is an insulator. But special rubber tyres of aircraft are made slightly conducting. |
| 3. | Vehicles carrying inflammable materials usually have metallic ropes touching the ground during motion. |
| 4. | A bird perches on a bare high power line and gets a fatal shock. A man standing on the ground touches the same line and nothing happens to the man. |
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