Chuck asked in Science & MathematicsPhysics · 3 years ago

# Errors in an experiment of ohm's law?

The aim of experiment is To investigate the relationship between voltage and current for both a light bulb filament and an exposed filament.

I have to find possible errors. I already found some:

1. The procedure involves using a light bulb, which when an electric current passes through it begins to heat up. Since, temperature is a factor affecting resistance, a drawback of the procedure is that we get an error due to this increase in temperature of the light bulb filament which is not quantifiable.

2. In the case of the bulb filament, this error is not significant in affecting the readings as water has a very high specific heat capacity and absorbs any heat evolved. This cannot be done for the bulb as due to the glass covering and it being filled with an inert gas, the filament still heats up.

3. The formula for calculation of resistance imply standard temperature and pressure i.e. 273K and 1 atmosphere of pressure. However, my experiment was carried out in a temperature in excess of 403K accounting for a deviation from the actual value.

4. The Internal resistance of the battery source was not provided and hence it is an error that is not quantifiable.

Can anyone suggest any other possibel error?

Relevance
• 3 years ago

1 is correct, except the "errors" are quantifiable, just difficult.

#2 how does water come into this?

#3, Resistance formula do NOT require (or imply) STP. The formula is valid over whatever temperature range that the resistance does not change by an appreciable amount. Kind of vague, but that's the way it works. A 1% resistor is guaranteed to be within 1% as long as you don't exceed the rated power. That rating is selected so that the temperature of the resistor at that power will not change the value by more than the spec.

#4. No, the error is easily quantifiable. And if you used voltage and current measurements to get the power, then that error would have no effect on your measurements. In any case, it can be calculated. I'd just leave out the words "not quantifiable".

I have to infer the experiment from your hints, as you don't describe it directly. some errors are:

voltmeter error

ammeter error

operator error in reading the meters

timing errors, ie, you did not allow enough time for the readings to stabilize

temperature errors in that the water temperature was still changing