resistance problem?

Question

the total power consumed by two resistors , connected in a parallel is 25 watts .if the voltage applied is 5 volts dc and the current in one resistor is 1.5 ampere ,what are the resistances of the two resistors?

Answer 1

the entire current, I = P/V
or, I = 25/5
so, I = 5 A

The branch currents I1 and I2 total upto I.

so, I1 + I2 = I = 5
but, I1 = 1.5
so, 1.5 + I2 = 5
or, I2 = 5 - 1.5
so, I2 = 3.5

the first resistance, R1 = V/I1
or, R1 = 5/1.5
so, R1 = 3.33 ohms (ans.)

the second resistance, R2 = V/I2
or, R2 = 5/3.5
so, R2 = 1.428 ohm (ans.)

Hope this was helpful.

Answer 2

Let resistors be r1 and r2
Total current = 25/5 A = 5 A
Current thro` r1 = 1.5 A
r1 = 5 / 1.5 ohms = 3.33 ohms
Current thro` r2 = 3.5 A
r2 = 5 / 3.5 ohms = 1.43 ohms

Answer 3

resistor with 1.5A = 5V divide by 1.5A
power = V^2 div R
V^2 = 25V, R therefore is 1 ohm.
if the two parallel combined resistors = 1ohm which one of them is 5/1.5 ohm, you should be able to find the other resistance.

Voltage across parallel resistors are equal.

Answer 4

Let resistors be r1 and r2
Total current = 25W/5 A = 5 A
Current through r1 = 1.5 A
r1 = 5 / 1.5 amps = 3.33 ohms
Current through r2 = 3.5 A
r2 = 5 / 3.5 amps = 1.43 ohms

Answer 5

P=V^2/R
R=V^2/P=5^2/25=1 (ohm)