thermometers , temperature heat

For a thermometer to work well should its heat capacity be lower, same, or higher than the objects being measured?

Heat capacity is how much energy is needed to increase temperature?

Therefore the heat capacities would have to be the same for both the thermometer and the objects. There is an example in my text book about monoatomic gases converting all their energy into kinetic energy. However diatomic and polyatomic gasses need extra heat to convert to kinetic energy.

• Imagine a thermometer which had an infinite heat capacity, so it absorbed lots of energy but its temperature didn't change. Would that be a good thermometer? – zeldredge Jan 18 '17 at 5:18
• @zeldredge It doesn't sound like a good thermometer because its not reading the temperature after absorbing lots of energy – kal Jan 18 '17 at 22:59
• You are correct. You want a thermometer that can absorb the least amount of energy possible and still give the correct temperature. – Ben S Jan 19 '17 at 1:51