Select the correct statement.

Options

A. Electric field intensity is zero at the centre of an electric dipole
B. Net electric field intensity inside a conductor is always zero in electrostatic condition
C. Dielectric constant of a medium may be less than one
D. Dielectric materials are not affected by electric field

Answer

To solve the question of selecting the correct statement regarding electric charges and fields, we will analyze each of the given statements step by step.

### Step 1: Analyze the First Statement
**Statement:** Electric field intensity is zero at the center of an electric dipole.

- An electric dipole consists of two equal and opposite charges, +Q and -Q, separated by a distance (let's say 2L).
- At the center of the dipole, the electric fields due to both charges will be equal in magnitude but opposite in direction.
- However, since they are equal and opposite, the net electric field at the center is not zero; instead, it is directed along the axis of the dipole.
- **Conclusion:** This statement is incorrect.

### Step 2: Analyze the Second Statement
**Statement:** Net electric field intensity inside a conductor is always zero.

- In electrostatic equilibrium, charges within a conductor redistribute themselves in such a way that the electric field inside the conductor becomes zero.
- This occurs because free charges move to the surface of the conductor, canceling any internal electric fields.
- **Conclusion:** This statement is correct.

### Step 3: Analyze the Third Statement
**Statement:** Dielectric constant of medium may be less than 1.

- The dielectric constant (relative permittivity) of a medium is defined as the ratio of the permittivity of the medium to the permittivity of free space (vacuum).
- The dielectric constant of vacuum is defined as 1. All other materials have a dielectric constant greater than or equal to 1.
- **Conclusion:** This statement is incorrect.

### Step 4: Analyze the Fourth Statement
**Statement:** Dielectric materials are not affected by electric fields.

- When a dielectric material is placed in an electric field, it becomes polarized. This means that the charges within the dielectric material shift slightly, creating an induced dipole moment.
- The presence of the electric field affects the dielectric material, changing its properties.
- **Conclusion:** This statement is incorrect.

### Final Conclusion
After analyzing all the statements, we find that the correct statement is:

**Correct Answer:** The net electric field intensity inside a conductor is always zero.