# P3 Revision Sheet ```P3 REVISION – CHAPTER 1 – MEDICAL APPLICATIONS OF PHYSICS
X-rays:
Explain what an x-ray is:
Describe some of the safety issues
with X-rays:
Ultrasound:
Describe how an ultrasound works: Explain how an ultrasound can be
used to measure distance:
Describe what a CT scanner is:
Lenses:
Describe how a convergent lens works:
Explain some of the therapeutic
uses of ultra sound:
Endoscope:
Describe how an endoscope works: Describe how we use endoscopes in
medicine:
Describe how a divergent lens works:
Describe how the lens works in the eye:
Refraction index:
sin 𝑖
The refractive index of the substance, 𝑛 =
sin 𝑟
Where 𝑖 is the angle of incidence and 𝑟 is the angle of refraction.
KEY WORDS:
Refraction index
Endoscope
Charge-couple
Converging lens
device
Diverging lens
CT scanner
Principal focus
Transducer
Magnifying
A-scan
Focal length
Refraction
Image
Snell’s law
ASSESSMENT:
P3 REVISION – CHAPTER 2 – USING PHYSICS TO MAKE THINGS WORK
Moments:
Describe what a moment it:
Complete the equation:
Moment = ____ X perpendicular distance
from the line of the force
to the pivot
______ newtons
________
______
Nm
m
Centre of mass:
Describe what the centre of mass of an
object is:
Draw the centre of mass on these shapes:
Moments in balance:
When a see-saw is balanced:
• the anticlockwise moment due to W1
• the clockwise moment due to W2 about
the pivot = W2d2
Calculate W1, if W2 = 7.0N, d1 = 0.40m and
d2 = 0.25m
Circular motion:
Explain centripetal force and the factors
that affect it:
Stability:
Explain the following:
Tractor safety:
The pendulum:
Describe the motion of a pendulum:
Bus tests:
The frequency of the oscillations is the
number of complete cycles of oscillation per
second.
High chairs:
the time period =
(in seconds, s)
Hydraulics:
Describe how machines use hydraulics:
KEY WORDS:
The formula for pressure is:
Pressure (Pa or N/m2) =
𝑓𝑜𝑟𝑐𝑒 (𝑁)
𝑎𝑟𝑒𝑎 (𝑚2 )
Effort
Pivot
Line of action
Centre of mass
Equilibrium
Moments
Resultant
Pressure
Pascal (Pa)
Hydraulic
Centripetal
Oscillation
Amplitude
Frequncy
1
𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦 𝑜𝑓 𝑡ℎ𝑒 𝑜𝑠𝑐𝑖𝑙𝑙𝑎𝑡𝑖𝑜𝑛𝑠 (𝑖𝑛 ℎ𝑒𝑟𝑡𝑧,𝐻𝑧)
ASSESSMENT:
P3 REVISION – CHAPTER 3 – USING MAGNETIC FIELDS TO KEEP THINGS MOVING
Explain how an electromagnet works:
Explain Fleming’s left hand rule:
Explain electromagnetic induction:
The transformer equation is:
𝑝𝑑 𝑎𝑐𝑟𝑜𝑠𝑠 𝑝𝑟𝑖𝑚𝑎𝑟𝑦,𝑉𝑃
𝑝𝑑 𝑎𝑟𝑜𝑠𝑠 𝑠𝑒𝑐𝑜𝑛𝑑𝑎𝑟𝑦,𝑉𝑆
=
𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑢𝑟𝑛𝑠 𝑜𝑛 𝑝𝑟𝑖𝑚𝑎𝑟𝑦,𝑛𝑝
𝑛𝑢𝑚𝑏𝑒𝑟𝑠 𝑜𝑓 𝑡𝑢𝑟𝑛𝑠 𝑜𝑛 𝑠𝑒𝑐𝑜𝑛𝑑𝑎𝑟𝑦,𝑛𝑠
If the transformer is 100% efficient:
𝑝𝑜𝑤𝑒𝑟 𝑠𝑢𝑝𝑝𝑙𝑖𝑒𝑑 𝑡𝑜 𝑡ℎ𝑒 𝑡𝑟𝑎𝑛𝑠𝑓𝑜𝑟𝑚𝑒𝑟 = 𝑝𝑜𝑤𝑒𝑟 𝑑𝑒𝑙𝑖𝑣𝑒𝑟𝑒𝑑 𝑏𝑦 𝑡ℎ𝑒 𝑡𝑟𝑎𝑛𝑠𝑓𝑜𝑟𝑚𝑒𝑟
𝑝𝑟𝑖𝑚𝑎𝑟𝑦 𝑝𝑑 &times; 𝑝𝑟𝑖𝑚𝑎𝑟𝑦 𝑐𝑢𝑟𝑟𝑒𝑛𝑡 = 𝑠𝑒𝑐𝑜𝑛𝑑𝑎𝑟𝑦 𝑝𝑑 &times; 𝑠𝑒𝑐𝑜𝑛𝑑𝑎𝑟𝑦 𝑐𝑢𝑟𝑟𝑒𝑛𝑡
𝑉𝑃 &times; 𝐼𝑃 = 𝑉𝑆 &times; 𝐼𝑆
Explain how an electric motor works:
Explain how a transformer works:
KEY WORDS:
South pole
North pole
Magnetic pole
Magnetic field
lines
Motor effect
‘Split-ring’
commutator
Induction
Transformer
National grid
Step-up
transformer
Step-down
transformer
ASSESSMENT:
```