A thermometer bulb is wrapped in cotton wool soaked in ethanol (a volatile liquid) at room temperature. Air at room temperature is blown across the soaked cotton wool.
What happens to the thermometer reading and what is the reason for this change?
It remains constant because both the air and the ethanol are at room temperature.
It falls because the evaporation of ethanol absorbs thermal energy from the thermometer bulb.
It rises because the friction of the moving air warms the ethanol.
It falls because conduction transfers heat from the thermometer to the cooler air.
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.