# A 2.2k resistor is rated at '1/2 W'. What is the highest voltage you could apply to the resistor without damage to it from overheating?

Would appreciate any help! Thank you

Hi thank you for the answers, just to clarify, the resistor is 2.2 ohms, not 2.2 thousand ohms. The answer given is also 33V. I tried the equation you provided morningfox but I came up with v = sqrt1.1

Any more help would be greatly appreciated, I'm struggling on this one

### 8 Answers

- MorningfoxLv 71 month agoFavourite answer
watts= volts * amps

Volts = ohms * amps

So watts = volts^2 / ohms

In this problem, you have 0.5 W = V^2 / 2200.

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The original question clearly had 2.2k. "k" means kilo, as in thousand. Changing the question like you did is called "bait and switch", and is generally regarded as unfair. It's not a "clarification", it is a change to a different question. What next? Are you going to give another "clarification" ... it wasn't 1/2 W, it was 1/2 kilowatt?

- Anonymous3 weeks ago
With R = 2.2k ohms, E = 33 v

With R = 2.2 ohms, E = 1.05 v

Approximately

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- 1 month ago
watts= volts * amps

Volts = ohms * amps

So watts = volts^2 / ohms

In this problem, you have 0.5 W = V^2 / 2200. hh

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- RobertLv 41 month ago
Most half watt resistors have voltage ratings of 350V . There are a few that will take 500 to 600 volts. There is also high voltage metal film types that can operate with 2.5kV.

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- roderick_youngLv 71 month ago
Let me work backwards from the answer, assuming R is unknown.

P = E^2/R

0.5 = 33^2/R

R = 33^2/0.5 = 1089*2 = 2178, which is approximately 2.2k

If the problem says 2.2 ohms, there's probably a typo, and it's supposed to be 2.2k ohms.

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- PhilomelLv 71 month ago
p=E^2/R >>.5=E^2/2.2 >>2.2*.5=1.1=E^2

sqrt(1.1)=1.05 V I=1.05/2.2=.477A

check .477*1.05=.5W

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- Anonymous1 month ago
Use Watts = V^2/R

0.5 = V^2/2200

V^2 = 2200 x 0.5

V^2 = 1100

V = sqr Root of [1100]

V = 33.16V

V = 33V

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- Anonymous1 month ago
E=IR so you could use a shortcut and just cut the "R" in half (because of the 0.5W) and that would be 1100 volts

1100 volts would result in a current of 0.5 amps. Power would be 550 watts, not 0.5 W. The resister would blow up, or melt very fast.

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@Ray: K when used with resistances, means kilo. Kilo means thousand. 2.2kΩ means 2.2 kilohms which means 2200 ohms.