Question

In the given circuit, A, B, C and D are four lamps connected with a battery of 60V

 

Analyse the circuit to answer the following questions. 

(i) What kind of combination are the lamps arranged in (series or parallel)? 

(ii) Explain with reference to your above answer, what are the advantages (any two) of this combination of lamps? 

(iii) Explain with proper calculations which lamp glows the brightest? 

(iv) Find out the total resistance of the circuit.

Answer 1

The lamps are in parallel. 

Advantages: 

If one lamp is faulty, it will not affect the working of the other lamps. They will also be using the full potential of the battery as they are connected in parallel. 

The lamp with the highest power will glow the brightest. 

P=VI 

In this case, all the bulbs have the same voltage. But lamp C has the highest current. 

Hence, for Lamp C 

P=5 x 60 Watt = 300 W. (the maximum). 

The total current in the circuit = 3+4+5+3 A = 15A 

The Voltage = 60V 

V=IR and hence R =$\frac{V}{I}$

= $\frac{60}{15}$ A = 4A