Paper 1 final notes Flashcards
How does a loudspeaker work
a.c. power supply provides the wire with a current that is always changing direction
-the magnetic field interacts with the current in the coil exerting a force
-the magnetic field is alternating causing the force to change direction back and forth
-the paper cone vibrates and a longitudinal sound wave is formed.
What is the distribution of the current and the voltage in a series circuit?
The current is the same throughout and the voltage splits across components
What is the distribution of the current and the voltage in a parallel circuit?
The current splits throughout components and the voltage stays the same.
How does an earth wire act as a safety feature?
-The earth wire is connected to the metal casing
-The earth wire provides a low resistance route to the earth
-The earth wire has a fuse connected to it that melts and breaks the circuit when the current is too high.
Define a.c.
Current that is continuously changing direction
Define d.c.
Current that only travels in one direction
What is a circuit breaker
A device that stops any current from flowing when the current is too high.
Do Filament Lamps and Diodes obey Ohms law
No they don’t as current isn’t proportional to voltage.
What is the relationship between light and resistance in a Light resistor
As light increases resistance decreases
What is the relationship between temperature and resistance in a thermistor
As temperature increases the resistance decreases
Why does resistance increase as the temperature of the filament increases?
Because the positive ions vibrate more inhibiting the flow of electrons.
What is a fuse?
A safety device that melts and breaks the circuit when the current is too high
What colour are earth, live and neutral wires
Earth wires are green and yellow
Neutral wires are blue
Live wires are brown
What is double insulation
When the wires inside a device and the outer case of the device are insulated - there is no chance of electrocution.
What are the EM waves starting from the largest wavelength
Radio
Microwaves
Infrared
Visible light
UV light
X-rays
Gamma rays
What are the uses of EM waves
Radiowaves: communication
Microwaves: Heating food
IR: Cooking
Visible light: Viewing objects and photography and communication
UV light: Fluorescent lamps and markings
X-rays: Viewing the internal structure of objects
Gamma rays: Kills cancer cells
Harm caused by EM waves:
IR: Can damage surface cells due to skin burn
UV: can cause skin cancer
Gamma: can cause cell mutations if exposed for too long.
How to prevent harm from EM waves
-Wear suncream and sunglasses for UV
-Limit exposure time to X-ray and stand behind a lead screen
-Limit exposure time to Gamma
Similarities of EM waves
-They are all transverse
-They all transfer energy
-They can all be reflected, refracted
-They all move at the same speed in free space.
How to make X-rays
X-rays are made when high-speed electrons are stopped
How to make Gamma
Gamma rays are emitted from unstable nuclei
What is a hard magnetic material?
Something that is difficult to magnetise and difficult to demagnetise
What is a magnetic field
The area between magnets where magnetism can be detected
What are magnetic field lines
Lines that present the direction of the magnetic field.
