Question

1.An electric iron of resistance 20 ohm takes a current of 5 ampere. Calculate the heat developed in 30 second.

(a) 15kj (b) 16kj (c) 20kj (d) 5kj​

Answer 1

Answer:

Given

An electric iron of resistance 20 Ω takes a current of 5 A

Find out

We have to calculate the heat developed in 30 s.

Solution

The amount of heat (H) produced is given by the joule’s law of heating as

H= Vlt

Where,

Current (I) = 5 A

Time (t) = 30 s

Voltage (V) = Current x Resistance

V = 5 x 20

V = 100V

H= 100 x 5 x 30

H = 1.5 x 104 J.

Therefore, the amount of heat developed in the electric iron is 1.5 x 104 J.

your ans is A) 15kj

Answer 2

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Given :-

Resistance of the iron = 20 ohm          

Current = 5 ampere          

Time = 30 seconds  

To Find :-

Heat Produced.

Formula to be used :-

Heat produced = I²RT    

Solution :-

Putting all the values, we get

Heat produced = I²RT          

Heat produced = 25 × 20 × 30          

Heat produced = 15000 Joules.

Hence, the heat produced in 30 seconds is 15000 Joules.

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