Which will produce more heat in 1 second – 1 ohm resistance on 10V or a 10-ohm resistance on the same voltage? Give reason for your answer.

Which will produce more heat in 1 second – 1 ohm resistance on 10V or a 10-ohm resistance on the same voltage? Give reason for your answer.

Ans: – We know, Q/t = v^2 / R,

So, from the upper relation it is clear that the circuit which has more resistance will have low power.

 

How will the heat produced in a conductor change in each of the following cases ?

As heat (H)= I^2RT.

(i) The current flowing through the conductor is doubled.

Ans: – Heat will be four times from previous one.

 

(ii) Voltage across the conductor is doubled.

Ans: – Heat will be four times from the previous one.

 

(iii) Time for which current passed is doubled.

Ans: – Heat will be double.

 

1 A current flows though a conductor of resistance 10 ohms for 1/2 minute. How much heat is produced in the conductor?

Ans: – Heat will be (H) = I^2× R×T,

Or, H= 1× 10× 1/2×60=300j.

 

Two electric bulbs of 40 W and 60 W are given. Which one of the bulbs will glow brighter if they are connected to the mains in (i) series and (ii) parallel?

Ans: – We know, power(p)= v^2/R;

So, from the upper relationship it is clear that the if the resistance is maximum will produce lowest brightness.

 

How is 1 kW h related with SI unit of energy?

Ans: – 1 kilowatt = 3.6 × 10^6j.

Name two household electric devices based on thermal effect of electric current.

Ans: –  Heater and electric cooker.

 

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