phy mc qs.......
2. The lengths of mercury thread in the uniform tube above the bulb of a mercury thermometer are:
30mm when the bulb is melting ice; 180mm when the bulb is in the steam above boiling water; 12mm when the bulb is in a liquid, what is the temperature of the liquid?
How to know the answer?
- 1 十年前最愛解答
Length of mercury thread changes in direct proportion to the liquid temperature.
Melting Ice = 0 deg C
Steam = 100 deg C
Let y be the temperature of the liquid:
therefore y = -12 deg C or Answer is B
- 魏王將張遼Lv 71 十年前
By the fact that the expansion of mercury is linear with temperature, we have:
Length of mercury thread at 0°C = 30 mm
Length of mercury thread at 100°C = 180 mm
So the temperature θ (in °C), for a given length of thread L, are related by:
L = 30 + θ × (180 - 30)/100
So when L = 12, we have:
12 = 30 + θ × 150/100
θ = -12
Hence the temperature is -12°C.
Answer = B資料來源： My physics knowledge