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# AS Physics - Sensor experiments, thermocouple - help? watch

1. I've been given an experiment to do for our coursework on OCR. I have to calculate the resolution and sensitivity of a thermocouple

Now I have no idea how to go ahead with this, they are going to give me a tray with the equipment on it, and I have to go from there, so I don't know what equipment I'm going to have

I'm going to presume water fro changing the temperature, and a multimeter to measure the resistance

Any help would be really great, since I only have til tomorrow
2. First you need to know what a thermocouple is.
You will not be measuring its resistance in this experiment.
http://en.wikipedia.org/wiki/Thermocouple
Secondly, you need to be clear what you mean by "resolution" and "sensitivity".
3. Right excellent. This is absolutely ridiculous, everyone else has things like "Measure the conductivity of a wire" or "Measure the resistance of an LDR for varying light intensities"

I have no idea what I'm after tbh. Sensitivity is meant to be the change in output over the change in input, but sensitivity varies at different temperatures, so how I'm meant to get a value for that confuses me.

And resolution is the smallest detectable change in output per change in input
Which again varies, so I'm pretty confused
4. The variation of emf with temperature will depend on the metals used.
An iron-constantan thermocouple has a large range of values over which the emf varies linearly with temperature difference.
For experiments with water up to 100 C there is a good linear relationship.
You could expect an emf of about 0 to 5mV over the range 0 to 100C and a good straight line.
You keep one junction in iced water and the other one in your warm water with a thermometer.

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