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.
How to increase the magnetic field strength of an electromagnet
-Increase the current
-Turn the wire into a coil
How to increase the magnetic field strength of a coil
Increase the number of turns on the coil
Increase the current
What is a motor
A wire that spins
How is the motor effect created
Two permanent magnets have a current carrying wire inbetween them.
-The two magnetic fields interact exerting a force on the wire causing it to spin
Fingers for Flemming’s Left hand rule?
Thumb = force
First Finger = Field
Second Finger = Current
What is the definition of specific heat capacity
The amount of energy needed to heat 1kg of an object by 1 degree.
How does a motor spin?
The current carrying wire experiences a temporary magnetic field
This magnetic field interacts with the magnetic field of the permanent magnets
-A force is exerted on the wire causing it to spin.
What is the role of brushes
-Conducts current between stationary wires and rotating wire of motor.
Roles of commutators
-Reverses the current every half turn to ensure the motor continues turning.
What is a galaxy
A galaxy is a collection of billions of stars
What is a universe
A universe is made up of billions of galaxies
What does gravitational pull maintain in space
-It keeps planets orbiting stars
-It keeps comets orbiting stars
-Keeps the moon orbiting planets
-Keeps satellites orbiting planets
What is a satellite
An object that orbits a planet
What does the strength of gravitational pull on a planet depend on
The mass of the planet
The distance between the planet and the sun
At what point of a comet’s orbit does it move fastest
-Closest to the sun as the gravitational pull is greatest here
Life cycle of a star similar to the sun
Nebula
Main sequence
Red Giant
White dwarf
Black dwarf
How does nebula become main sequence
Gravitational pull allows hydrogen nuclei to get closer for fusion to occur
How does main sequence become a red giant/red supergiant
The main sequence runs out of hydrogen fuel and burns helium instead causing it to expand
How does Red giant become white dwarf
The star shrinks
How does white dwarf become black dwarf
The star cools
Life cycle of a very high mass star
Nebula
Main sequence
Red supergiant
Supernova
Neutron star/black hole.
How does a red supergiant become a supernova
A huge explosion
What colour are very hot stars
Blue
What colour are cooler stars
Red
What is absolute magnitude
How the brightness of a star appears from a fixed distance
