Physics - End of Year 9 Exam

Static electricity

Static electricity

Build-up of electric charge on a surface

When static electricity occurs

Substance has been rubbed against another substance

Static electricity is caused by

Electrons rubbing off from one substance to another, making one substance positively charged whilst the other becomes negatively chargedd

Spark formation

When electrons are released in one go, converted to heat, light, sound and kinetic energy

Current electricity

Made up of electrons moving along a wire in an electric current

Electric circuit

Electrons travel along a path called an electric circuit

Energy source

Provides the electrons with the energy needed to move them around the circuit

Energy user

Converts energy provided by the electrons to another form

Current

Flow of charged particles (e.g. electrons)

Current is made up of

Electrons

Types of current

Alternating and direct current (AC/DC)

Alternating current

Electrons shuffle back and forth along the wire (supplied by powerpoints)

Direct current

Electrons all flow in the same direction (supplied by batteries)

Measurement for current

Measured by an ammeter in the units ampere or amps (A or I)

Ammeter function

Measures amount of charge that flows through it each second

Voltage

The amount of energy

Voltage use

Used by charges as they pass through an energy user component, leading to a voltage drop

Voltage measurement

Measured using a voltmeter in the unit volts (V)

High voltage

Electrons are supplied with a lot of energy or are losing lots of energy

Low voltage

Electrons lack energy or lose very little energy

V =

I x R

I =

V / R

R =

V / I

Temperature

Result of the movement of particles, measure of kinetic energy

Influencer of temperature

Depends on the speed of the movement of particles

Heat

Transfer of kinetic energy, total energy of particles within a substance

Heat transfer

Heat flows from areas of higher temperature to those of lower temperature

Influencer of heat transfer

The greater the temperature, the faster the heat flows

Conduction

Rapid vibration of particles in one substance transferring the vibration to a second substance

Conductors

Substances that transfer heat easily (metals)

Insulators

Substances that transfer heat poorly (plastics)

Convection

The rising and sinking of particles of different heat (liquids and gasses)

Density of heated particles

Less dense so they rise

Density of cooled particles

More dense so they sink

Convection current

As the cooled particles reach the point of heating, they begin to rise, whilst the heated particles rise, they become further away from the heat source, leading them to cool down and sink again

Radiation

Transmission of heat as invisible waves that travel at the speed of light

Reaction to radiation

Absorption, reflection, transmission

Influencers of absorption, reflection and transmission

Temperature, colour and material

Transversal waves

Up/down movement - surface tension

Longitudinal waves

Left/right movement - chain reaction

Sound waves

Vibration of particles propagating outwards from the source

Amplitude

Strength of the wave

Impact of amplitude

Changes the volume

Wavelength

Distance between recurring points

Frequency

Number of waves per second

High frequency

Sound is high pitch

Low frequency

Sound is low pitch

Foundation of light

Made up of capsules of energy (photons)

Formation of photons

As electrons lose energy, their orbit becomes smaller and a photon is released

Electromagnetic waves

Amount of energy that photons have changes how they interact with other substances

Types of light waves

Radio, microwave, infrared, visible, ultraviolet (UV), x-ray, gamma ray