Question

Mobility is the drift velocity per unit

• A. charge
• B. volume
• C. electric field
• D. current
• E. time

Hint:

Mobility tells how easily charge carriers move under an electric field: \(\mu = v_d/E\).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Mobility of a charge carrier (like an electron or a hole in a semiconductor) is a measure of how quickly it can move through a material when an electric field is applied. It quantifies the relationship between the drift velocity of the carrier and the applied electric field.
Step 2: Key Formula or Approach:
The mobility (\( \mu \)) is defined by the formula:
\[ v_d = \mu E \] where \( v_d \) is the drift velocity of the charge carrier and E is the magnitude of the applied electric field.
From this definition, mobility can be expressed as the ratio of drift velocity to the electric field.
Step 3: Detailed Explanation:
Rearranging the formula \( v_d = \mu E \), we get:
\[ \mu = \frac{v_d}{E} \] This equation explicitly states that mobility (\( \mu \)) is the drift velocity (\( v_d \)) per unit electric field (E). A higher mobility means that the charge carriers achieve a higher drift velocity for a given electric field, indicating they move more easily through the material.
Step 4: Final Answer:
Mobility is the drift velocity per unit electric field. This corresponds to option (C).