Which of the follwing characteristies of electrons determines the current in a conductor?

Options

A. Drift velocity alone
B. Thermal velocity alone
C. Both drift velocity and thermal velocity
D. Neither drift nor thermal velocity

Answer

To determine which characteristic of electrons influences the current in a conductor, we can analyze the relationship between current, charge, and drift velocity.

### Step-by-Step Solution:

1. **Understand the Definition of Current:**
Current (I) in a conductor is defined as the rate of flow of charge. Mathematically, it is expressed as:
\[ I = \frac{Q}{t} \]
where \(Q\) is the charge and \(t\) is the time.

2. **Relate Charge to Electrons:**
The charge \(Q\) can be expressed in terms of the number of electrons (n) flowing through a cross-sectional area (A) of the conductor:
\[ Q = n \cdot e \]
where \(e\) is the charge of a single electron (approximately \(1.6 \times 10^{-19} \, \text{C}\)).

3. **Define 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 a measure of how fast the electrons are moving in the direction of the electric field.

4. **Current in Terms of Drift Velocity:**
The current can also be expressed in terms of drift velocity:
\[ I = n \cdot A \cdot e \cdot V_d \]
Here, \(A\) is the cross-sectional area of the conductor, \(n\) is the number of free electrons per unit volume, and \(V_d\) is the drift velocity.

5. **Identify the Key Factor:**
From the equation \(I = n \cdot A \cdot e \cdot V_d\), we can see that the current depends directly on the drift velocity (\(V_d\)). While the number of free electrons and the cross-sectional area also play a role, the drift velocity is the primary characteristic that determines the current in a conductor.

6. **Conclusion:**
Therefore, the characteristic of electrons that determines the current in a conductor is the **drift velocity**.

### Final Answer:
The characteristic of electrons that determines the current in a conductor is **drift velocity**.