Question

In Milikan’s experiment, a static electric charge on the oil drops was obtained by shining X-rays. If the static electric charge on the oil drop is –1.282 × 10¹⁸C, calculate the number of electrons present on it.

Answer 1

Given:

Charge on oil drop, Q = −1.282 × 10⁻¹⁸ C
Charge of one electron, e = 1.602 × 10⁻¹⁹ C

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Step 1: Use relation between charge and number of electrons

Q = n × e

n = Q / e

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Step 2: Calculate number of electrons

n = (1.282 × 10⁻¹⁸) / (1.602 × 10⁻¹⁹)

n = 8

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Final Answer:

Number of electrons present on the oil drop = 8