Temperature dependence of drift velocity depends on the following factors.

Options

A. Number of charge carriers can change with temperature
B. Time interval between two successive collisions can depend on the temperature
C. Length of a material is a function of temperature
D. Mass of a material is a function of temperature

Answer

To analyze the temperature dependence of drift velocity, we need to consider the factors that influence it. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand Drift Velocity
Drift velocity (\(v_d\)) is the average velocity that a charge carrier, such as an electron, attains due to an electric field. It is influenced by several factors.

**Hint:** Recall the definition of drift velocity and its significance in current flow.

### Step 2: Identify Factors Affecting Drift Velocity
1. **Number of Charge Carriers**: The drift velocity is directly proportional to the number of charge carriers (electrons) in the conductor. More charge carriers lead to more collisions, which can increase the drift velocity.

**Hint:** Think about how the density of charge carriers in a material affects the flow of current.

2. **Time Interval Between Collisions**: The time interval (\(\Delta t\)) between successive collisions of the charge carriers also affects drift velocity. A longer time interval allows the carriers to gain more velocity before colliding again, thus increasing the drift velocity.

**Hint:** Consider how the frequency of collisions impacts the motion of electrons in a conductor.

### Step 3: Consider Other Factors
- **Length of the Conductor**: The length of the conductor does not affect the drift velocity. While the length may change due to thermal expansion with temperature, this change is negligible in the context of drift velocity.

**Hint:** Reflect on how the physical dimensions of a conductor relate to the flow of current.

- **Mass of Charge Carriers**: The mass of the charge carriers remains constant and does not change with temperature. Therefore, it does not affect the drift velocity.

**Hint:** Remember the law of conservation of mass in the context of charge carriers.

### Step 4: Conclusion
Based on the analysis, the temperature dependence of drift velocity primarily depends on:
- The number of charge carriers.
- The time interval between collisions.

Thus, the answer is that the temperature dependence of drift velocity depends on the number of charge carriers and the time interval between successive collisions.

**Final Answer:** The temperature dependence of drift velocity depends on:
1. Number of Charge Carriers
2. Time Interval Between Collisions