Chapter 21, Problem 5STP

To determine

The way, the electric field is measured in Millikan’s oil drop experiment.

Explanation of Solution

Introduction:

Millikan conducted an oil drop experiment to test whether charge existed as a multiple of some fundamental amount or not. He balanced the weight of a charged oil drop in an electric field to find that the net charge is always a multiple of a number $1.6\times {10}^{-19}\text{ C}$ .

Millikan measured the electric field from the electric potential difference between the plates.

  $E\text{=}\frac{\Delta V}{d}$

Where, $\Delta V$ is the potential difference applied and $d$ is the distance between the plates.

Conclusion:

B is the correct answer. Millikan measured the electric field from the electric potential difference between the plates.