Question

What will be the heat when resistance is 4 times?according to joule's law

Answer 1

According to Joules Law,

H = Vit or H = V²t/R

In other words,

H ∝ 1/R __(1)

This directly points that, Heat and Resistance are inversely propotional values where if one will decrease then another will increase in same order.

If resistance is increased 4 times then,

H' ∝ 1/R' where R' = 4R

So, H' ∝ 1/4R __(2)

By dividing eq(2) by eq(1)

⇒ H'/H = 1/4R ÷ 1/R

⇒ H'/H = 1/4R × R/1

⇒ H'/H = 1/4

⇒ H' = 1/4 × H

Hence, New heat will be 1/4th of the original heat.

Thus, when Resistance is increased by 4 times then Heat will decrease till 4 times by Joule's Law.