What type of oil should be used in Millikan's oil drop experiment ?

Explanation

To determine the type of oil that should be used in Millikan's oil drop experiment, we need to consider a few key factors regarding the properties of the oil.

### Step-by-Step Solution:

1. **Understanding the Experiment**: Millikan's oil drop experiment is designed to measure the charge of an electron by balancing the gravitational force on tiny oil droplets with the electric force acting on them.

2. **Choosing the Oil**: The oil used in the experiment should have a low vapor pressure. This is crucial because if the vapor pressure is too high, the oil droplets can evaporate when subjected to the electric field and the conditions of the experiment.

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