Question

7. An electric geyser consumes 2.2 units of electrical energy per hour of its use. It is designed to work on the mains voltage of 220 V.
a) What is the ‘power-rating’ of this device?
b) What is the current flowing through this device when it is connected across the ‘mains’?
c) What is the ‘resistance’ of this device?
d) Does the resistance of this device remain constant during its operation/working? e) Cost of energy consumed if each unit cost rupees 6.00.

Answer 1

Answer:

we know that

1 unit=1KWH=3.6×10^6J

2.2units=7.92×10^6J

V=220V

(a) energy=7.92×10^6J

time=3600s

Power=7.92×10^3/3.6

=2200W

(b)I=P/V=2200/220=10A

(c)R=V/I=220/10=22ohms

(d) During working of electric geyser, temperature increases due to that, resistance may also increase

(e)cost of 1 unit=Rs6/-

cost of 2.2units=Rs13.2/-