Question

an electric iron of resistance 20 ohms takes a current of 5A calculate the heat developed in 30 seconds​

Answer 1

Given :-

Resistance of the electric iron, R = 20Ω

current , I = 5A

time taken, t = 30s.

To find :-

the heat developed in 30s.

Solution :-

here, we can use Joules law of heating

According to joules law of heating,

The heat produced in a resistor is directly proportional to

• the square of current for a given resistance ( H ∝ I²)
• the resistance for a given current (H ∝ R)
• the time for which the current flows through the resistor (H ∝ t).

.i.e.,

• H = I²Rt

here, H denotes heat, I denotes Current, R denotes resistance and t denotes time.

So using joules law of heating,

➠ H = I²Rt

➠ H = (5)²(20)(30)

➠ H = (25)(600)

➠ H = 15000J

thus, the heat developed by the electric iron in 30s is 15000J$.$

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Answer 2

$\huge \bf AnSwEr: -$

⇢ H = I²Rt

⇢ H = (5)²(20)(30)

⇢ H = (25)(600)

⇢ H = 15000J