1.

A parallel combination of three resistors takes a current of 7.5A form a 30V supply. If the two resistors are 10Ω and 12Ω find which is the third one?

Answer»

The resistance of the group of 3 resistors is equal to

R = 30 V / 7.5 A = 
4 ohm.

Let R3 be the resistance of the third resistor, then

1/R = 
1/10 + 1/12 + 1/R3
so,

1/4 = 1/10 + 1/12 + 1/R3

1/R3 = 1/4 
- 1/10 - 1/12 
= 15/60 - 6/60 - 5/60 
= 4/60
Hence 
R3 = 60/4 = 15 ohm



Discussion

No Comment Found

Related InterviewSolutions