Question

A 1000 watt heating coil is cut into two equal parts if the two parts are used separately as heaters what will be their combined wattage ​

Answer 1

the correct answer is 4000w

my solution is explained below

let the original coil have resistance r........the new have resistances r/2.......

initially we get a wattage of (v^2)/r ......

but now we have 2 coils having half the original resistance.........and they are connected in parallel......so new combined coil resistance (R) is 1/R= 2/r+ 2/r.......so R=r/4........

so new power of the combined coil is

(v^2)/(r/4) = 4 {(v^2)/r}. i.e. 4times the initial power.... so answer is

4*1000=4000W