my tutor says i'm wrong......???

[Unregistered]

My tutor asked me a question.............."If on a certain circuit,if we were to double the resistance and half the voltage.......what would be the outcome?(VOLTAGE)
MY ANSWER......1/4 OF THE ORIGINAL VOLTAGE.......Am i right or wrong???

[dznewz]

A: Half the original voltage

[mdshunk]

The voltage would not change. The question stated that the voltage was cut by 1/2.

The effect would be that the power (in watts), would be reduced by exactly 8 times.

Do this simple example:

Consider a 120 volts applied to a 10 ohm load. 120 x 120 / 10 = 1440 watts

Now consider 60 volts applied to a 20 ohm load. 60 x 60 /20 =180 watts

Plug in whatever numbers you want. Just half the voltage and double the resistance, like the question asks, and you will have a power reduction of 8 times.

The other obvious outcome is that the circuit would generate about 8 times less heat.

[Unregistered]

Sorry !!! my mistake..........the answer he wanted was in watts ..not volts...SO I AM RIGHT.....IT WOULD BE REDUCED TO 1/4......REDUCED BY X8

[mdshunk]

Nope, you're still wrong. A 1/4 reduction would be only reducing it by 4 times.

The 8 times reduction could also be expressed by as a 1/8 reduction.

[donb]

I don't know guys...the question said that the voltage was halved. It looked to me like he was asking what the new voltage was. So...for what it is worth...I agree with dznews...the voltage is half of the original voltage :)

[donb]

Sorry...I didn't notice the follow-up reply indicating the answer was to be in watts!

[Roger]

Well, I agree with Mdshunk if we are strictly looking at this as typical Ac circuit or ohms law you would have a 75% reduction in current and power would reduce 8 times. You also are not showing us how you are deriving your answer of 1/4 the voltage or half the voltage, then you say watts????

[joed]

P=ExE/R if the volts is 1/2 and the resistance is 2
then
1/2 x 1/2 / 2
= 1/8