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

Options

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

Explanation

To determine which characteristic of electrons affects the current in a conductor, we can analyze the relevant concepts in current electricity. Here’s a step-by-step solution:

### Step 1: Understand Current in a Conductor
Current (I) in a conductor is defined as the flow of electric charge. The formula for current can be expressed as:
\[ I = \frac{Q}{t} \]
where \( Q \) is the charge and \( t \) is the time.

### Step 2: Relate Current to Charge Density and Drift Velocity
The current density (J) can be defined as:
\[ J = \frac{I}{A} \]
where \( A \) is the cross-sectional area of the conductor. The current density can also be expressed in terms of the number of charge carriers (n), the charge of each carrier (e), and their drift velocity (v_d):
\[ J = n \cdot e \cdot v_d \]

### Step 3: Express Current in Terms of Drift Velocity
From the relationship between current density and current, we can derive the expression for current:
\[ I = J \cdot A = n \cdot e \cdot v_d \cdot A \]
Thus, we can see that:
\[ I = n \cdot e \cdot v_d \]
This shows that the current depends on the number of charge carriers (n), the charge of each carrier (e), and importantly, the drift velocity (v_d).

### Step 4: Identify the Key Characteristic
Among the characteristics of electrons, the drift velocity (v_d) is the key factor that determines the current in a conductor. The thermal velocity, while present, does not contribute to the net current as it represents random motion rather than directed flow.

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

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