Unit 2 Tutorial

CC2404 Applied Physics and Instrumentation in Health Care Problems Unit 2 2.1

What does it mean to say that two bodies are in thermal equilibrium?

2.2

Give an example of a physical property that varies with temperature and describe how it is used to measure temperature.

2.3

When a cold mercury thermometer is placed in a hot liquid, the column of mercury goes down slightly before going up. Explain why.

2.4

For every 100 J of electrical energy which enters a television set 10 J of useful light energy is produced and 5 J of useful sound energy. (a) Calculate the efficiency of the television set (b) Suggest what form the remaining energy might have changed into.

2.5

Explain why a metal window frame feels cold when you touch it but a plastic window frame does not feel so cold.

2.6

Explain why two sheets of glass separated by a thin layer of air (double glazing) will provide better insulation for your house than a single piece of glass which has twice the thickness.

2.7

What is the Fahrenheit temperature of a person with a 39.0 °C fever?

2.8

To conserve energy, room temperatures are kept at 68.0 °F in the winter and 78.0 °F in the summer. What are these temperatures on the Celsius scale?

2.9

Name three methods by which thermal energy can move. Which of these methods is the only one which will carry thermal energy through a vacuum?

2.10 A bimetallic strip is made from aluminium and copper. When heated it bends in the direction shown in the figure below. Which metal expands more for the same rise in temperature? Draw a diagram to show how the bimetallic strip would appear if it were cooled to below room temperature. 2.11 Explain greenhouse effect. 2.12 When water in the vapor phase condenses, is the surrounding air warmed or cooled? 2.13 Which of the following methods is not used for core temperature measurement? (a) thermistor (b) mercury thermometer (c) liquid crystal thermometer (d) thermocouple