2514296
Descripción
Mapa Mental por miles.a.moran, actualizado hace más de 1 año
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Creado por miles.a.moran
hace más de 9 años
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Physics P3
- Medical Applications
- X-Rays
- Process
- High energy photons are projected onto
the body part which is being x-rayed
- The photons cause a chemical reaction in
the exposed areas of film to reveal the bone
- The photons cause a chemical reaction in
the exposed areas of film to reveal the bone
- High energy photons are projected onto
the body part which is being x-rayed
- An ionising type of radiation
- This can cause cancer or death
- This can cause cancer or death
- Safety precautions
- Warning lights to show
x-ray production
- Shielding the x-ray
source with lead
- Wearing lead aprons
- X-ray film badge to show
high levels of radiation
- Warning lights to show
x-ray production
- Process
- Ultrasound
- Human hearing range 20Hz - 20,000Hz
- The reflection
- When ultrasound is transmitted from one medium to another. Some of
the sound is reflected and some is absorbed. Gel is used to avoid the air
medium as the Ultrasound will travel at a different speed through the air
- When ultrasound is transmitted from one medium to another. Some of
the sound is reflected and some is absorbed. Gel is used to avoid the air
medium as the Ultrasound will travel at a different speed through the air
- Distance (S) = Speed of Sound (V) x Time taken (T)
- Uses
- Foetus imaging
- Shattering kidney stones
- Sonar
- Foetus imaging
- Human hearing range 20Hz - 20,000Hz
- CT Scans (Computerised Tomography)
- X-Ray machine spins around
- The body is moved through the machine
- Advantages
- Produces a 3D image
- Distinguishes between different tissues
- Produces a 3D image
- Disadvantages
- High exposure to X-ray radiation
- Equipment is expensive
- High exposure to X-ray radiation
- X-Ray machine spins around
- X-Rays
- Lenses
- Refraction
- Refractive Index = Sin i / Sin r
- When light changes direction whilst
passing from one medium to another
- Critical Angle - The angle of incidence where the
refracted ray makes 90° with the normal line
- Refractive Index = Sin i / Sin r
- Convex Lens
- Convex Ray Diagram
- Real image
- Inverted
- Bigger
- Real image
- Convex Ray Diagram
- Concave Lens
- Concave Ray Diagram (Magnifying Glass)
- Virtual image
- Upright
- Smaller
- Virtual image
- Concave Ray Diagram (Magnifying Glass)
- The Eye
- Range of Vision
- The ciliary muscles change the
shape of the less to allow the eye to
focus on object at various distances
- Close Objects - The muscles contract and the lens becomes rounder
- Distant Objects - The muscles relax and the lens becomes thinner
- The ciliary muscles change the
shape of the less to allow the eye to
focus on object at various distances
- Correcting Eyesight Problems
- Convex lens is used to correct long sight
- Concave lens is used to correct short sight
- Convex lens is used to correct long sight
- Range of Vision
- Lens Power (Dioptres) = 1 / Focal Length (Metres)
- Refraction
- Mass
- Centre of Mass - The point at which the
whole mass of an object is concentrated
- Pendulum
- Period (Seconds) = 1 / Frequency (Hertz)
- The period is increased by
the length of string only
- A cycle is from one
position and returning to it
- Period (Seconds) = 1 / Frequency (Hertz)
- Turning Effect and Moments
- Moment = Force (Newtons) x Distance to pivot (Metres)
- Levers - Force multipliers
- Moment = Force (Newtons) x Distance to pivot (Metres)
- Stability
- An object is stable as long as the line of action of its weight passes through the base
- An object is stable as long as the line of action of its weight passes through the base
- Hydraulics
- Pressure (Pa) = Force (N) / Area (M^2)
- Pressure in a liquid acts equally in all directions
- Liquids are incompressible
- Pressure (Pa) = Force (N) / Area (M^2)
- Circular Motion
- When moving in a circle an object is constantly
changing direction thus it is accelerating
- The acceleration acts towards
the centre of the circle
- The force which cause the
acceleration is Centripetal Force
- When moving in a circle an object is constantly
changing direction thus it is accelerating
- Centre of Mass - The point at which the
whole mass of an object is concentrated
- Electromagnetic Fields
- Electromagnets
- The wire is usually wound
around a bar made of soft iron
- To increase the force
- Increase the current
- Increase the number of turns in the wire
- Increase the current
- The wire is usually wound
around a bar made of soft iron
- The Motor Effect
- To Increase the force
- Increase the current
- Increase the strength
of the magnetic field
- Increase the current
- There is no force if the current
is parallel to the field direction
- The Motor
- The split ring commutator swaps the battery
connections every half turn to enable the coil
to keep rotating in the same direction
- The split ring commutator swaps the battery
connections every half turn to enable the coil
to keep rotating in the same direction
- To Increase the force
- Electromagnetic Induction
- 1. A conductor cuts through a magnetic field
- 2. If the wire is part of a complete circuit, a
potential difference is induced in the wire
- 2. If the wire is part of a complete circuit, a
potential difference is induced in the wire
- 1. Magnet enters coil - Potential difference induced
- 2. Magnet stops - No potential difference
- 3. Magnet removed - Potential difference
induced in the opposite direction
- 3. Magnet removed - Potential difference
induced in the opposite direction
- 2. Magnet stops - No potential difference
- 1. A conductor cuts through a magnetic field
- Transformers
- Primary Voltage/Secondary Voltage = Primary Turns/Secondary Turns
- Made of lamintaed(layered) iron core
- Used to increase or decrease voltage
- Switch-Mode Transformers
- Used to convert AC - DC
- Almost 100% efficient
- Used to convert AC - DC
- Primary Voltage/Secondary Voltage = Primary Turns/Secondary Turns
- Electromagnets
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