Card Set Information
Physics Health Physics
Standard Grade Physics - Health Physics
The temperature of an object is a measure of how hot or cold it is.
What is the unit for temperature?
Degrees celcius (°C)
What do we measure temperature with?
Name three different types of thermometers
Liquid in glass
Digital (thermistor) thermometer
Rotary (bimetallic strip)
Explain what is special about the
inside the clinical liquid in glass thermometer?
A clinical liquid in glass thermometer will have a "kink" to prevent the liquid falling
Give three differences between a clinical liquid in glass thermometer and an ordinary liquid in glass thermometer
The scale is smaller on a clinical liquid in glass thermometer (35 - 42 °C) than an ordinary liquid in glass thermometer
A clinical thermometer is more sensitive (as it has small divisions of 0.1 °C) than an ordinary liquid in glass thermometer
In a clinical liquid thermometer ther reading sticks at the highest value because the mercury inside breaks when measured from the patient
Sound can travel through....?
Sound cannot travel through....?
How does a stethoscope work?
Sounds picked up at the chestpiece are transmitted up the air in the tubing to the earpieces
What is a humans range of hearing?
20 Hz - 20 000 Hz (decreasing with age)
High frequency vibrations beyond the range of human hearing (abovve 20 000 Hz) are called _________?
Describe how ultrasound is used to obtain images of a baby in its mother's womb
The waves are emitted by a probe and reflected by tissues and bones of the foetus from different depths, so a 3D picture can be built up
Jelly or oil is placed between the probe and the skin. This excludes the air to prevent the ultrasound being reflected at the change from air to tissue. The waves would then not enter the woman's body
The reflected waves are detected and the patterns of reflection times are used to build up an image on a computer monitor
Light travels in straight lines called ____?
When light passes from one material into another of different density, its shape changes and so its direction changes - this is known as ________?
Convex lenses have a _______ power?
Concave lenses have a _______ power?
What is the formula for focal length?
P = 1/f
The image of an object formed on the retina is ______ _____ and ______ ______?
laterally inverted (back to front)
To correct long sight a ______ lens is placed in front of the eye?
To correct short sight a ________ lens is placed in front of the eye?
Light passes along an optic fibre by......?
total internal reflection
Fibre optics can be used to transfer _____ light into the body?
Give three uses of lasers in medicine
Laser eye surgery
Vaporising Cancer Tumors
Removing Tattoos/Birth Marks
Name one use of infra-red in medicine
Detect cancerous tissue
To help heal injured muscles
Name one use of ultraviolet in medicine
To sterilise hospital equipment
To treat Vitamin D deficiency and some skin disorders
Too much exposure to ultraviolet radiation can be harmful because......?
it can cause sunburn and even skin cancer
Name one use of x-rays in medicine
To see inside people
To kill cancer tumours (in high doses)
Describe how photographic film can be used to detect x-rays
Photgraphic film goes dark where x-rays hit. This leaves white patches on the film where the bones were in the way
Describe how computerised tomography or a CAT scan works
Using a special X-ray machine which rotates around the body, x-ray images of the body are taken in thin slices.
A computor combines all these images to provide a three - dimensional picture of the body
Radioactivity can knock electrons out of atoms. This is known as _____?
Name the three types of radioactivity
How far can alpha radiation travel and what is it stopped by?
A few cm
How far can beta radiation travel and what is it stopped by?
A few mm of aluminium
How far can gamma radiation travel and what is it stopped by?
What is the unit of
What type of radiation causes the most ionisation?
What does dose equivalent take into account?
The biological effect of radiation depends on.....?
type of tissue
absorbing the radiation
State the meaning of the term half-life
The time for a radioactive substance's activity to decrease by 50%
What is activity measured in?