Question

If the voltage across a fixed resistance is doubled, what happens to the current?

- It doubles.
- It halves.
- It stays the same.
- The current cannot be determine

Final Answer

(a)

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This is College Physics Answers with Shaun Dychko.
Ohm's Law says voltage equals current times resistance and so we can solve this for current by dividing both sides by

*R*. So we have in the first case in the first circuit, we have current one equals the voltage one divided by*R*and I did not put a subscript on the R because we're told that the resistance is fixed, so it's the same for both circuits. Now in circuit two, we have the voltage two divided by the same resistance*R*. But*V two*we're told is double*V one*and so I've substituted two*V one*in place of*V two*. Now we see that this part is*I one*and so*I two*is two times*I one*. So the answer is A, it doubles.