Electrician's Licensing Practice Exam

For a circuit with a source of 10V and a resistance of 2 ohms, what is the appropriate fuse value?

1. 2 amperes

2. 5 amperes

3. 10 amperes

4. 7 amperes

The correct answer is: 5 amperes

To determine the appropriate fuse value for this circuit, we can apply Ohm's Law, which states that voltage (V) equals current (I) multiplied by resistance (R), or expressed mathematically as V = I * R. In this case, the voltage of the circuit is 10 volts, and the resistance is 2 ohms. We can rearrange the equation to find the current: I = V / R = 10V / 2Ω = 5A. This calculation shows that the circuit will draw a current of 5 amperes when operating at the specified voltage and resistance. When selecting a fuse, it is essential to choose one that can handle the normal operating current without blowing under typical conditions. A fuse rated for exactly 5 amperes would trip at the maximum current, which could disrupt operation. Therefore, a fuse rated slightly higher than the operating current is appropriate. 5 amperes is the ideal choice in this scenario, as it allows for normal operation without the risk of nuisance tripping from minor fluctuations in current, while also protecting the circuit from overload conditions. The other choices either fall below or significantly exceed this value, which could either result in frequent interruptions during operation or lack sufficient