Q5 of 50 Page 379

Why the cord of a heating element does not glow while the heating element glows?

The glow of an element is due to the power dissipation of the element. The power of an element is given by


As the resistance of the heating element is higher than the cords, the power dissipation of the heating element is greater and it glows.


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3

State the factors that alter the resistance of a conductor. Write the mathematical expression.

 4

State Joules low of heating and give its expression.

 6

What is the commercial unit of electrical energy? Convert it into joule. What is the other name of the commercial unit? What is meant by a parallel combination of resistors? Deduce an expression for the equivalent resistance when two resistor are connected in parallel.

 7

Two resistors of 5 Ω and 10 Ω are connected in parallel. Eight such sets are connected in series.

Find the equivalent resistance of this combination.