Question

An heating element supplies 300kj in 50 minutes find the p.d

Answer 1

Complete Question:

A heating element supplies 300 kJ in 50 minutes. Find the p.d. across the element when the current is 2 A.

Given:

Work Done, W = 300 kJ

Time, t = 50 minutes = 50 x 60 seconds

            = 3000 seconds

Current through the element, I = 2 A

Find:

The potential difference (V) across the element.

Solution:

According to the definition of power, we have

$Power = \frac{Work}{Time}$

$P = \frac{W}{t}$

Putting the values of W and t, we have

$P = \frac{300kJ}{3000s}$

$P = 0.1 kW = 100 W$

As we know, another formula for power is $P = VI$

where V = Potential difference across the element

           I = Current through the element

Putting the value of current (I) in the above equation, we get

$P = VX2\\100 = 2V\\V = \frac{100}{2} \\V = 50 V = 50 volts$

Hence, the p.d. across the element is 50 volts.

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