Question

If the length of the filament of a heater is reduced by 10% ,the power of the heated will:

A) increase by about 9%
B)decrease by about 10%
C)increase by about 19%
D)increase by about 11%

(answer this with proper calculation and explanation )​

Answer 1

it will definitely decrease

Answer 2

Answer:

When length dec by 10 percent resistance becomes (9/10)th of original resistance and

$p = {i}^{2} r$

so power becomes 9/10th of original power ie dec by 10 %