## What is the value of resistor R?

The currents in two resistors in a circuit are shown in the figure. Here's the URL to the picture given: http://i55.tinypic.com/mvnmfm.jpg

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##### Answer

R and the 200 Ω resistor are in parallel, so they have the same potential difference = volts

V = I * R

V = 1.5 * 200 = 300 Volts

The sum of the current through R and the 200 Ω resistor = 2.5 amps

Current through R = 2.5 – 1.5 = 1 amp

Volt for R = 300 Volts

300 = 1 * R

R = 300 Ω

Check:

Equivalent resistance = 1 ÷ (1/200 + 1/300) = 120 Ω

Total current = 2.5 amp

Total voltage = 2.5 * 120 = 300 Volts

V = IR

V of R is the same with the 200 ohm

and I of R is 2.5 - 1.5 = 1

V of R = V of 200 ohm

IR = IR

1R = 1.5 * 200

R = 300

First you must find the voltage in the resistance of 200ohms

V=IR so

V=300Volts

Then you know that the voltage of the resistance R is 300V since is parallel to the resistance of 200ohms

The current of 2.5 gets divided into 1.5A and 1.0A, so the resistance is:

R=V/I

R=300V/1A

R=300ohms

R and the 200 ohm resistors are in parallel so the voltage across both of them would be the same

Voltage across 200 ohm resistor = 200*1.5 = 300V

current through R resistor = 2.5 - 1.5 = 1 Ampere

Voltage through R resistor = 300 = R*1

therefore R = 300 ohms