Stumped On A Revision Question...

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sprocketflup

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Im currently studying part time for the 2330 lvl 3, as its a part time course (2 hours a week) you are expected todo most of your teaching yourself at home. I havent got a problem with that, in fact, I work quite well that way.

Ive really had time to immerse myself the last few days, and have got a lot done. Just for for the sake of it, I did a little mock exam that I was sent by as fellow TEF member a while back. When it came to marking, I did ok on the bits Ive studied so far, and not so good on the bits i havent, as expected really.

However one (relatively simple or so I thought) question has got me a bit stumped, and I cant work it out. See what you think

28 - An electric heater dissipates a power of 3.0 kW when connected to a 230 V a.c. supply. The resistance of the heater is :
a   13.0 Ω.
b   15.65 Ω.
c   17.6 Ω.
d   35.2 Ω.

 

Now i did  a quick calculation and answered a) 13.04ohms. Yet when it came to marking time the answer sheet is insisting that the answer is c) 17.6ohms. This is repeated in two different versions of the exam that I have found.

So what have I overlooked? i thought maybe about True power and Apparent power but cant see how you would define the losses in order to work it out

 
Im currently studying part time for the 2330 lvl 3, as its a part time course (2 hours a week) you are expected todo most of your teaching yourself at home. I havent got a problem with that, in fact, I work quite well that way.

Ive really had time to immerse myself the last few days, and have got a lot done. Just for for the sake of it, I did a little mock exam that I was sent by as fellow TEF member a while back. When it came to marking, I did ok on the bits Ive studied so far, and not so good on the bits i havent, as expected really.

However one (relatively simple or so I thought) question has got me a bit stumped, and I cant work it out. See what you think

28 - An electric heater dissipates a power of 3.0 kW when connected to a 230 V a.c. supply. The resistance of the heater is :

a   13.0 Ω.

b   15.65 Ω.

c   17.6 Ω.

d   35.2 Ω.

Now i did  a quick calculation and answered a) 13.04ohms. Yet when it came to marking time the answer sheet is insisting that the answer is c) 17.6ohms. This is repeated in two different versions of the exam that I have found.

So what have I overlooked? i thought maybe about True power and Apparent power but cant see how you would define the losses in order to work it out
wrong formula - you have calculated amps

try R= V² / P

 

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