Physics Quick recap Flashcards
What color is neutral wire
blue
What color is earth wire
Green/Yellow
What color is live wire
Brown
What does earthing and fuse do
Prevent fires and shocks
fuses
Surge in current melt the fuse which cuts off live suppy
Circuit breakers
It break circuit by opening a switch when detect a surge in current
Transverse waves meaning
Vibrations are perpendicular to direction energy is transferred by waves
Longtidunal
Vibrations are parallel to direction energy transferred by waves
What does waves transfer
Waves transfer energy and information without matter
Uses of EM
Radiowaves
Microwaves
Infrared
Visible light
Ultraviolet
X-rays
Gamma
Radiowaves Communication
Microwaves - satellite communication and heating food
Infrared - Heating and monitor temp
Light signals can travel thru optical fibres
Visible light - for photography
Ultraviolet - Fluorescent lamp
X-rays - see inside things
Gamma - Sterilise food and medical equipment
How optical fibres fur helps bear heat up its body
- Light signals always totally internally reflected
- due to optical fibres being narrow
- therefore incidence angle greater than critical angle
what happens if angle of incidence is greater than critical angle
Total internal reflection
What is convection
more energetic particles move from hotter region to cooler region and transfer energy as they do.
Immersion heater
- water heats
- hot water = less dense
- less dense water rises
- fast moving particles collide with slow moving particles and transfer energy
- water cools and become denser
- denser water sinks again
Reduce rate of energy transfer
Conduction
convection
radiation
insulation
Conduction =
- use materials with low conductivity
- insulation
Convection=
- Insulation
- stop fluid moving
insulation =
- clothes, blankets, foam activity wall
- they traps air
- material in between also have low thermal conductivity
Radiation =
poor emitter - shiny and white
Particle theory
- gas particles collide
- exert force
- momentum and direction change
- creating outward pressure
k in units
times 1000
M in units
times 1 000 000
m in units
divide by 1000
n in units
divide by 10 to the power of 9
4 factors speed up DC electric motor
1) more current
2) more tunes on the coil
3) Stronger magnetic field
4) Soft iron core in the coil
How does loudspeaker work
- A.C current produce magnetic field
- constantly changing magnetic field
- interacts with permanent magnet
- using Fleming LHR
- force exerted towards coil and pull back in
- coil oscillate making cone oscillate
cone oscillate makes air oscillates which create sound waves
How to get bigger voltage in generator
- strength of magnet
- number of turns in coil
- speed of movement
How does generator works
Wire move through magnetic field and induce voltage
