Question

By using heating effect of current heaters are used for generating heat. In a heater, the coil generates 30 J of heat. Now this coil is cut into eight equal parts and only one part is now used in the heater. The heat generated will now be

Answer 1

Given:

By using heating effect of current heaters are used for generating heat. In a heater, the coil generates 30 J of heat. Now this coil is cut into eight equal parts and only one part is now used in the heater.

To find:

Heat generated ?

Calculation:

Let us consider that the initial resistance of the coil is R , so heat produced will be :

$\sf \therefore \: H = \dfrac{{V}^{2} }{R} \times t = 30 \: joule$

But. now the coil is cut into 8 parts ,

$\sf \therefore \: \dfrac{R_{2}}{R} = \dfrac{( \frac{l}{8}) }{l}$

$\sf \implies\: \dfrac{R_{2}}{R} = 8$

$\sf \implies\: R_{2} = 8R$

So, new heat generated:

$\sf \therefore \: H_{2} = \dfrac{{V}^{2} }{R_{2}} \times t$

$\sf \implies\: H_{2} = \dfrac{{V}^{2} }{ (\frac{R}{8})} \times t$

$\sf \implies\: H_{2} = 8 \times (\dfrac{{V}^{2} }{R } \times t)$

$\sf \implies\: H_{2} = 8 \times 30$

$\sf \implies\: H_{2} = 240 \: joule$

So, new heat generated is 240 Joules