Q45 of 330 Page 60

Two exactly similar electric lamps are arranged (i) in parallel, and (ii) in series. If the parallel and series combination of lamps are connected to 220 V supply line one by one, what will be the ratio of electric power consumed by them?

As we know that

Electric power consumed = V2/R


Here V is given we have to find the value of R


So when the connection is in parallel


The equivalent resistance is



Electric power consumed in parallel connection



When the connection is in Series


The equivalent resistance = R+R = 2R


Electric power consumed in series connection



The ratio of electric power consumed by them



More from this chapter

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43

A boy noted the readings on his home’s electricity meter on Sunday at 8 AM and again on Monday at 8 AM (see Figures below).


(a) What was the meter reading on Sunday ?


(b) What was the meter reading on Monday?


(c) How many units of electricity have been used ?


(d) If the rate is Rs. 5 per unit, what is the cost of electricity used during this time?

 44

An electric bulb is rated as 10 W, 220V. How many of these bulbs can be connected in parallel across the two wires of 220 V supply line if the maximum current which can be drawn in 5A ?

 1

How does the heat H produced by a current passing through a fixed resistance wire depend on the magnitude of current I?

 2

If the current passing through a conductor is doubled, what will be the change in heat produced?