Question

1. State the joule 's law of heating .
2. an electric appliance is rated 200 W ,250 V . This appliance is connected to 250 V mains . Calculate
A. Current drawn
B. Electrical energy consumed in 60 hours
C . If the cost of electricity is 2.00 per commercial unit , find the cost of electricity in above part .

Answer 1

Joules law states that the heat produced in a conductor by a constant current is equal to the product of the square of the current and resistance of the conductor and the duration of time the current passes.

That is, Q = I²× R ×t,

where, Q is the heat produced in joules,

I is the current through the conductor in amperes,

R is the resistance of the conductor in ohms and,

t is the time in seconds.

i)Current drawn(I) = 200/250 ( As I = P/V )

= 0.8A

ii) Energy consumed = P x t

= 200 x 60

= 12000 J
= 12 KJ

iii) Cost of energy consumed = 12x 2.00

= Rs 24

Regards.