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?

    <p>Temperature</p> Signup and view all the answers

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

    <p>It becomes a gas</p> Signup and view all the answers

    What is the ultimate in cold?

    <p>Absolute zero (-273.15°C)</p> Signup and view all the answers

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

    <p>It increases</p> Signup and view all the answers

    What is the result of removing heat from a substance?

    <p>The temperature decreases</p> Signup and view all the answers

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

    <p>800-4000 nm</p> Signup and view all the answers

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

    <p>Infrared radiant heating</p> Signup and view all the answers

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

    <p>10 m</p> Signup and view all the answers

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

    <p>-196°C</p> Signup and view all the answers

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

    <p>Cooling rate during the freezing cycle</p> Signup and view all the answers

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

    <p>To help the survival of some cells</p> Signup and view all the answers

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

    <p>Non-cryogenic method</p> Signup and view all the answers

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

    <p>4°C</p> Signup and view all the answers

    Why do thermistors respond rapidly to temperature changes?

    <p>Because of their small mass</p> Signup and view all the answers

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

    <p>To monitor the patient's breathing rate</p> Signup and view all the answers

    What is the principle of operation of a thermocouple?

    <p>The conversion of temperature into electrical voltage</p> Signup and view all the answers

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

    <p>From -190 to 300 °C</p> Signup and view all the answers

    What is the primary application of thermography in medical diagnosis?

    <p>To detect breast cancer</p> Signup and view all the answers

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

    <p>Vasodilation</p> Signup and view all the answers

    What is the principle of conductive heating?

    <p>Heat transfer from a warmer object to a cooler object</p> Signup and view all the answers

    What is the purpose of heat therapy in medical treatment?

    <p>To increase blood flow to a specific area</p> Signup and view all the answers

    What is the principle behind the Liquid Glass Thermometer?

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

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

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

    What is the temperature of the human body in kelvin?

    <p>310.15 K</p> Signup and view all the answers

    What is the relationship between the Fahrenheit and Celsius scales?

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

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

    <p>To measure the temperature of a substance.</p> Signup and view all the answers

    What is the characteristic of a Thermistor?

    <p>It changes its resistance rapidly with temperature.</p> 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?

    <p>1.8% of its volume</p> Signup and view all the answers

    What is the formula to convert Kelvin to Celsius?

    <p>°C = K - 273.15</p> 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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    Heat And Cold In Medicine PDF

    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.

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