# A circuit with a resistance of 6 Omega has a fuse that melts at 8 A. Can a voltage of 12 V be applied to the circuit without blowing the fuse?

Apr 17, 2016

No, you would need a voltage of at least $48 V$.

#### Explanation:

We are interested here in the current, because if the current comes above a certain point the circuit will blow. The equation for current is

$I = \frac{V}{R}$.

We know that $R = 6 \Omega$, and that $12 V$ are being sent through the circuit, so

$I = \frac{12 V}{6 \Omega} = 2 A$

A current of $8 A$ will blow the circuit, so quite clearly a current of $2 A$ when the voltage is $12 V$ won't.

When current is at $8 A$ or above, then voltage must be

$V \ge 8 A \cdot 6 \Omega$
$V \ge 48 V$

for the circuit to break.