A platinum-resistance thermometer has a resistance of 5&O...
A platinum-resistance thermometer has a resistance of 5Ω at 0°C and 9Ω at l00°C. Assuming that resistance changes uniformly with temperature, calculate the resistance of the thermometer when the temperature is 45°C.
13.9 Ω
8.9 Ω
6.8 Ω
3.2 Ω
1.8 Ω
Correct answer is C
θ100=Rθ−R0R100−R0
45100=Rθ−59−5
45×4=100(Rθ−5)
180=100Rθ−500
180+500=100Rθ
Rθ=680100
Rθ=6.8Ω