Medical Physics: Heat and Temperature

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Questions and Answers

What is the primary source of energy that causes the temperature of a gas to increase?

The kinetic energy of the molecules

The motion of the solid molecules

The walls of the container

The energy transferred from a flame (correct)

What is the term for the total energy of molecular motion in a substance?

Heat (correct)

Temperature

Kinetic energy

Molecular motion

What happens to a solid when enough heat is added to it?

It becomes colder

It becomes a liquid (correct)

Its temperature remains constant

It becomes a gas

What is the term for a measure of the average energy of molecular motion in a substance?

Temperature Signup and view all the answers

What is the result of adding more heat to a liquid?

It becomes a gas Signup and view all the answers

What is the ultimate in cold?

Absolute zero (-273.15°C) Signup and view all the answers

What happens to the molecular kinetic energy when heat is added to a substance?

It increases Signup and view all the answers

What is the result of removing heat from a substance?

The temperature decreases Signup and view all the answers

What is the wavelength range of infrared radiant heating used for surface heating of the body?

800-4000 nm Signup and view all the answers

Which type of heating is considered to be more effective than conductive heating?

Infrared radiant heating Signup and view all the answers

What is the wavelength of the electromagnetic waves used in short wave diathermy?

10 m Signup and view all the answers

What is the temperature of liquid nitrogen used for medical purposes?

-196°C Signup and view all the answers

What is the main factor that affects cell survival after freezing?

Cooling rate during the freezing cycle Signup and view all the answers

What is the purpose of adding a protective agent before cooling in cryobiology?

To help the survival of some cells Signup and view all the answers

What is the conventional method of blood storage involving mixing whole blood with an anticoagulant?

Non-cryogenic method Signup and view all the answers

What is the temperature at which whole blood is stored in the conventional non-cryogenic method?

4°C Signup and view all the answers

Why do thermistors respond rapidly to temperature changes?

Because of their small mass Signup and view all the answers

What is the primary purpose of placing thermistors in a patient's nose?

To monitor the patient's breathing rate Signup and view all the answers

What is the principle of operation of a thermocouple?

The conversion of temperature into electrical voltage Signup and view all the answers

What is the range of temperatures that can be measured using a thermocouple?

From -190 to 300 °C Signup and view all the answers

What is the primary application of thermography in medical diagnosis?

To detect breast cancer Signup and view all the answers

What is the result of an increase in metabolism during heat therapy?

Vasodilation Signup and view all the answers

What is the principle of conductive heating?

Heat transfer from a warmer object to a cooler object Signup and view all the answers

What is the purpose of heat therapy in medical treatment?

To increase blood flow to a specific area Signup and view all the answers

What is the principle behind the Liquid Glass Thermometer?

The increase in temperature causes mercury to expand more than the glass. Signup and view all the answers

What is the sensitivity of a thermometer with a diameter less than 0.1mm?

It can measure temperature changes of 0.01 °C. Signup and view all the answers

What is the temperature of the human body in kelvin?

310.15 K Signup and view all the answers

What is the relationship between the Fahrenheit and Celsius scales?

°C =(5/9)*(Fo-32) Signup and view all the answers

What is the purpose of a thermometer in medical and biological purposes?

To measure the temperature of a substance. Signup and view all the answers

What is the characteristic of a Thermistor?

It changes its resistance rapidly with temperature. Signup and view all the answers

By how much does the volume of mercury in a thermometer change when going from 0 to 100 °C?

1.8% of its volume Signup and view all the answers

What is the formula to convert Kelvin to Celsius?

°C = K - 273.15 Signup and view all the answers

Study Notes

Physical Basis of Heat and Temperature

Matter is composed of molecules that are in motion, which have kinetic energy related to temperature.
Average kinetic energy of molecules is directly proportional to temperature in an ideal gas, liquids, and solids.
Heat is the total energy of molecular motion in a substance, while temperature is a measure of the average energy of molecular motion.

Temperature Scales

There are three types of temperature scales: Fahrenheit (F), Celsius (°C), and Kelvin (K).
Relationships between temperature scales are:
- Ko = 273.15 + °C
- °C = (5/9) × (Fo - 32)
- Fo = (9/5) × °C + 32

Thermometer

Liquid glass thermometer contains mercury and works by measuring the expansion of mercury with temperature.
Thermistor is a special resistor that changes its resistance rapidly with temperature, with a sensitivity of 5% per 1 °C.

Heat Therapy

Two primary therapeutic effects of heat therapy:
- Increase in metabolism resulting in vasodilation.
- Increase in blood flow as blood moves to cool the heated area.
Methods of producing heat in the body:
- Conductive heating through contact with a warmer object.
- Infrared (IR) radiant heating, which penetrates 3mm into the skin.
- Radio wave heating (diathermy) using electromagnetic waves.
- Microwave diathermy using waves in the radar range.
- Ultrasonic wave heating (ultrasonic diathermy) producing mechanical motion.

Cold in Medicine

Cryogenics is the science and technology of producing and using very low temperatures.
Cryobiology is the study of low temperature effects in biology and medicine.
Low temperature has been used for long-term preservation of blood, sperm, bone marrow, and tissues.
Cells survival after freezing is more dependent on the cooling rate during the freezing cycle than on the warming rate during the thawing cycle.

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Description

This quiz covers the physical basis of heat and temperature, including the motion of molecules in a gas, liquid, or solid, and their kinetic energy.