Question

An electric geyser has rating $2000\,W$, $200\,V$. What should be the minimum current rating (in whole number) of a fuse wire that may be required for safe use of this geyser?

Answer 1

Hint:In order to solve this question we need to understand fuse wire. Fuse wire is an electrical device that is used as a checker in electrical circuits on the electric current, it contains a wire which has a certain limit so when very high flow of current in an electrical circuit then fuse wire melts and the circuit breaks, so in this way it prevents the electrical devices from damage. Here, we will use the basic formula of electric power delivered to appliances and will find out the minimum rating of a fuse wire.

Complete step by step answer:
Power rating of fuse wire given is, $P = 2000W$
And the voltage rating is, $V = 200V$
Let the minimum current rating of fuse wire be, ${I_{\min }}$
Then from definition of power rating we get, $P = VI$
Putting value we get, $2000 = 200({I_{\min }})$
So minimum current rating is given as,
${I_{\min }} = \dfrac{{2000}}{{200}}$
$\therefore {I_{\min }} = 10A$

So minimum current rating is given as, ${I_{\min }} = 10\,A$.

Note: It should be remembered that although fuse wire is comparatively cheap but it is not safe because whenever there is high voltage in circuit and so high current, it melts with production of heat which is not safe as it may cause any other damage and fuse wire has low breaking capacity, so it is not most suitable for overload.