# basic electric theory (parallel power circuits)

#### xbox112005

Joined Oct 30, 2011
9
Need help with this question. Two resistors are connected in series.One resistor has a resistance of 1000 ohms,and the other resistor value is not known.The circuit is connected to a 50 v power supply,and there is a current of 25ma flowing in the circuit. If a 1500 ohm resistor is connected in parallel with the unknown resistor,how much current will flow in this circuit?

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#### praondevou

Joined Jul 9, 2011
2,942
50V and 25mA gives you the total resistance. Then calculate the unknown resistor.
You will have 1000 Ohms in series with the value just obtained and 1500 Ohms in parallel. Calculate the new total resistance and then the current.

#### Nathan Hale

Joined Oct 28, 2011
159
I am getting the answer as 31.25mA. What am i doing wrong?

#### praondevou

Joined Jul 9, 2011
2,942
I am getting the answer as 31.25mA. What am i doing wrong?
Nothing. Why do you think the answer is not 31.5mA?

#### xbox112005

Joined Oct 30, 2011
9
50V and 25mA gives you the total resistance. Then calculate the unknown resistor.
You will have 1000 Ohms in series with the value just obtained and 1500 Ohms in parallel. Calculate the new total resistance and then the current.
thanks but how did you get 42

#### Georacer

Joined Nov 25, 2009
5,182

#### praondevou

Joined Jul 9, 2011
2,942
LOL, that was really funny.............. 