Question

A fuse is rated $8A$.can it be used with an electrical appliance rated $5kW,200V$? Give a reason.

Answer 1

The concept of safe value current and the calculation of current from power rating of the electrical appliance is to be used here. If the value of current which comes from power rating of electrical appliance ,which is necessary for the working of appliance is more than the current rating of the fuse. Then the fuse cannot be used with the above electrical appliance.

Complete step by step answer:
Power is defined as the work done per unit. It is how fast electrical work can be done by any electrical component formula for power is
$power = voltage\,\,\times current$
Power rating of the electrical component is actually mentioned on the component that this much power is being delivered or absorbed by the component same is the case with voltage and current rating rating.
The electric component is to be made to operate at its current and voltage rating only excessive current or voltage may damage it .In such cases we use a fuse with measured current rating according to the component ,to protect the component.
For working of fuse,
Current rating of fuse > current for our component
Current for fuse=$8A$
Power for component=$5000Watts$
Voltage for component=$200Volts$
Current rating for electrical component=$\dfrac{5000}{200}Ampere$

Current $= 25Ampere$
Which is more than fuse current rating and hence the given fuse cannot work with the above electrical component.

Note:
A fUSE is an electrical safety device that operates to provide over current protection of an electrical circuit. Its essential component is a metal wire or strip that melts when too much current flows through it, thereby stopping or interrupting the current.it has to be a material of low melting point.