Final answer:
Electric fuses are rated in amperes indicating the maximum current they can carry before melting, which prevents overloading and damage to electrical appliances.
Step-by-step explanation:
Electric fuses are rated based on the current that they can safely carry without blowing, which is measured in amperes (or amps). The rating of a fuse corresponds to the maximum current it can handle before the fuse element melts, thereby opening the circuit and preventing the flow of current. This is crucial as it prevents overheating and potential fires caused by current overloads.
The proper rating for a fuse is typically a little higher than the normal working current of the electrical appliance it is protecting. This allows for occasional surges in current that can occur in normal operation without causing the fuse to blow unnecessarily. However, it must be low enough to ensure that the fuse will blow in the event of an overload or short circuit, thus protecting the wiring and appliance from damage.