Question

A 12 V cell is connected across two 4 ohm resistors which are connected in parallel when a third resistor was connected to the circuit in series with the parallel combination the current in the circuit 3A.Find the value of the third resistance​

Answer 1

Answer:

sorry I didn't know..............

Answer 2

Answer: 2 ohm

Explanation:

let us take the unknown resistance as r

I= 3A

V=12V

R=[(1/4+1/4)]^-1 +r           -----(as the two 4 ohm resistors are in parallel)

the two 4 ohm resistance will become a single resistance of 2 ohm in series with r

=> R=2+r

so,

R=V/I

=> 2+r = 12/3 = 4

=> r = 4-2 =2

thus, the third resistance is 2 ohms