Question

A parallel combination of three resistors takes a current of three resistors takes a current of 7.5A from a 3V supply. if two resistors are 10 and 20 find the third one.STEP BY STEP.

Answer 1

R=V/I

=3/7.5

=2/3ohm

• 3 resistors is 0.74ohm

Answer 2

Explanation:

let last resistor =r3

r1= 10

r2 =20

i=7.5

v =3

v =i*r

1/r=(1/r1)+(1/r2)+(1/r3)

because all are in parallel

1/r= (1/10)+(1/20)+(1/r3)

r =200 r3/(30+r3)

v = i*r

3 = 7.5(200*r3/(30+r3))

90+3*r3 = 1500 r3

r3= 0.06 ohm