MCAT Physics Question 82: Answer and Explanation

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Question: 82

7. How many moles of electrons pass through a circuit containing a 100 V battery and a 2 Ω resistor over a period of 10 seconds? (Note: )

A. 5.18 × 10^–3 moles
B. 500 moles
C. 5.18 × 10³ moles
D. 5.2 × 10⁶ moles

Correct Answer: A

Explanation:

To determine the moles of charge that pass through the circuit over a period of 10 s, we will have to calculate the amount of charge running through the circuit. Charge is simply current times time, and the current can be calculated using Ohm's law:

Then, calculate the number of moles of charge that this represents by using the Faraday constant and approximating F as

This is closest to choice (A).

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