Question

A bulb is rated at 330V-110W. what do you think is its resistence? three such bulbs burn for 5 hrs at a stretch. what is the energy consumed? calculate the cost in rupees if the rate is 70 paise per unit

Answer 1

we know that for an electric appliance

P = V2/R

or resistance will be given as R = V2 / P

So,

P = 110w

V = 330 volts

R = 3302 / 110

= 108,900/110 = 990

thus, resistance of the bulb is 990

now, electric energy consumed will be

E = number of units x power of each unit x time = n x P x t

n = 3

P = 110 W

t = 5 hours

so,

E = 3 x 110 × 5

thus,

E = 1650Wh

..

the total cost of electricity = total unit of energy consumed x cost per unit

= 1650 x 0.7 Rs

thus,

total cost= 1155rs.

and

monthly cost = total daily cost x number of days in month

=

1155rs. × 30 = 34,650rs.

hope this will help...