A shallow dish contains ethanol at room temperature. A student places a liquid-in-glass thermometer in the ethanol with its bulb just below the liquid surface. A draft of air is blown across the open top of the dish, and the temperature reading begins to decrease. Explain, in terms of ethanol molecules, why the temperature of the ethanol at the surface decreases.
The student then moves the thermometer bulb near the bottom of the dish while the draft continues to blow. After some time, the reading on this thermometer also decreases. State the name of the thermal transfer method causing this cooling at the bottom and explain what is happening in the liquid.
The thermometer used in this experiment has a specific range and sensitivity.
State what is meant by:
State and explain the effect on the sensitivity of the thermometer of using a capillary tube with a wider internal diameter (bore).
528 exam-style questions on CIE IGCSE Physics 2.2 Thermal properties and temperature, covering 2.2.1 Thermal expansion of solids, liquids and gases, 2.2.2a Internal energy and temperature, 2.2.2b Specific heat capacity, 2.2.3a Melting, boiling, condensation and solidification, 2.2.3b Evaporation, and 2.2.3c Cooling by evaporation. Each one has a worked solution and a mark scheme showing where the marks go.