When no current is passed through a conductor,

Options

A. (a)the free electrons do not move
B. (b)the average speed of a free electron over a large period of time is zero
C. (c )the average velocity of a free electron over a large period of time is zero
D. (d)The average of the velocities of all the free electrons at an instant is zero.

Answer

To solve the question "When no current is passed through a conductor," we need to analyze the behavior of free electrons in the conductor under these conditions.

### Step-by-Step Solution:

1. **Understanding Current**:
- Current (I) is defined as the flow of electric charge. It can be expressed mathematically as \( I = \frac{Q}{T} \), where \( Q \) is the charge and \( T \) is the time.

2. **Condition of No Current**:
- When no current is flowing through the conductor, it implies that there is no net movement of charge in any particular direction. This is typically the case when there is no potential difference applied across the conductor.

3. **Movement of Free Electrons**:
- Free electrons in a conductor are in constant motion due to thermal energy. However, this motion is random in nature.

4. **Average Velocity of Free Electrons**:
- The average velocity of free electrons over a large period of time is zero because their random motion cancels out. While individual electrons may move in different directions, the overall displacement averages out to zero.

5. **Instantaneous Velocity**:
- At any given instant, the average of the velocities of all free electrons is also zero for the same reason: the random directions of motion lead to a net average of zero.

6. **Conclusion**:
- Therefore, when no current is passed through a conductor, we conclude that:
- The average velocity of free electrons over a large period of time is zero.
- The average of the velocities of all the free electrons at an instant is also zero.

### Final Answer:
The correct options are:
- The average velocity of free electrons over a large period of time is zero.
- The average of the velocities of all the free electrons at an instant is zero.