Section 4 b) Key Words

Chemical energy: Stored energy in chemical form, possessed by food, fuel, batteries, etc.

Conduction: Energy transfer directly through an object where there is a difference in temperature.

Conserved: When energy is transferred from one form to another it is conserved; none is lost/destroyed.

Convection: The transfer of energy in a convection current through a fluid wherein warm material becomes less dense and rises and cool air becomes more dense and sinks.

Efficiency: How much energy is useful compared to how much is wasted.

Electrical energy: Energy wherein a current is flowing.

Insulation: An insulating material placed between cold and warm areas to limit energy transfers.

Kinetic energy: Anything that is moving has kinetic energy, also called movement energy.

Light energy: Energy emitted in the form of light, from the Sun, light bulbs, etc.

Nuclear energy: Energy released from nuclear reactions (e.g. atomic bombs)

Potential energy: Energy that is stored elastically or gravitationally. The object has been stretched or placed higher, giving it the potential to move.

Radiation: Energy transferred through infrared radiation. All objects have it and constantly emit and absorb it to match the surroundings.

Sankey diagram: A diagram used to show input and output of energy, a visual aid to see the efficiency of something.

Sound energy: Energy from vibrations emitted in sound waves.

Thermal energy: Heat energy, emitted from something hot and absorbed by something cold.

Section 3 d) Key Words

Amplitude: The distance between the crest of a wave and the neutral point 0. Larger amplitudes mean louder sounds (in sound waves)

Analogue signal: A signal that continuously varies. It is easily distorted and difficult to restore.

Angle of incidence: The angle at which a wave changes from one medium to another, compared to the normal.

Angle of refraction: The angle at which a wave is refracted from the perpendicular surface.

Bandwidth: The frequency of a wave. Digital signals have wider bandwidths, meaning they can carry more information at once.

Critical angle: The angle at which the wave is no longer refracted, but changes to becoming reflected.

Diffraction: When a wave passes an object and spreads beyond it. Its effect is affected by the wavelength in proportion to the size of the gap/blockage. If the gap is smaller in proportion to a larger wavelength, the effects of diffraction are greater.

Digital signal: A signal with only two settings, 0 and 1. It is easily restored and has a larger bandwidth than an analogue signal, so it is able to carry more information.

Frequency: How many times a wave is completed in one second.

Longitudinal waves: Waves that oscillate in the direction of travel. Sound waves are longitudinal.

Oscillation: The vibration. One wave.

Oscilloscope: A machine that measures the vibrations of a wave and creates a trace.

Pitch: How high or low a sound is. A flute makes a high-pitched noise, whereas a double bass makes a low-pitched noise.

Plane mirror: A completely flat mirror.

Reflection: When waves bounce off a surface they are reflected.

Refraction: The change in direction of waves after passing from one medium to another.

Refractive index: The refractive index of a medium tells us how much it will refract light waves. It can be found by this formula: n = sin i / sin r

Total internal reflection: When all waves are reflected inside a medium, none are refracted.

Transverse waves: Waves that oscillate perpendicular to the direction of travel. Light waves are transverse.

Virtual image: An image that is not real, it is a projection or reflection.

Section 3 c) Key Words

Electromagnetic spectrum: A spectrum of frequencies or wavelengths of electromagnetic radiation divided into 7 sections.

Electromagnetic waves: A wave produced by the acceleration of electric charge. It is transverse, so it oscillates perpendicular to the direction of energy travel.

Gamma rays: The highest frequency, and shortest wavelength on the electromagnetic spectrum.

Infrared: Waves with a lower frequency than visible light, but higher than microwaves.

Microwaves: Waves with a lower frequency than infrared, but higher than radio waves.

Radio waves: Waves with the lowest frequency, and longest wavelength found on the electromagnetic spectrum.

Ultraviolet (U.V.): Waves with a higher frequency than visible light, but lower than x-rays.

Visible light: Found in the middle of the electromagnetic spectrum, visible light is the light and colours we can see, split into 7 colours: red, orange, yellow, green, blue, indigo, violet.

X-rays: Waves with a higher frequency than U.V., but lower than gamma rays.

Section 3 b) Key Words

Amplitude: The height or size of a wave. Measured in metres.

Crest: The highest point of the wave.

Diffraction: When a wave is bent and spread as it passes around an edge or through a gap.

Frequency: The number of waves in a certain time period.

Longitudinal: A wave that oscillates parallel to the direction of travel (e.g. sound waves)

Transverse: A wave that oscillates perpendicular to the direction of travel (e.g. waves on the electromagnetic spectrum)

Trough: The lowest point of the wave.

Wavelength: The distance between the crests of two waves, the length of one wave.

Wave period: The length of time it takes for one wave to be completed.

Section 3 a) Key Words

Angle: The space between two intersecting lines close to or at the point they meet.

Degrees: A unit of measurement for angles.

Frequency: The number of crests of a wave that travel past a point in a given unit of time.

Hertz: A measurement of frequency, the number of waves that pass in one second.

Metres: A measurement of distance

Metres/second: A measurement of speed or velocity. How many metres travelled in one second.

Velocity: How fast something is moving in a particular direction; a vector quantity.

Section 2 d) Key Words

Conductor: A material that allows current to flow through it due to free charged particles.

Earthed: When an object allows its charge to flow to earth and becomes neutral.

Earthing strap: A flexible metal strap that provides a path of least resistance for charge to travel down to earth.

Electrostatic charge: An electric charge that is not in motion; it is not flowing. Basically electricity without the current.

Insulator: A material that does not allow current to flow through it as it has no free charged particles.

Static Electricity: Unmoving electricity, electrostatic charge.

Section 2 c) Key Words

Cell: Chemical power source, provides a circuit with electrical energy (basically a battery)

Current: The rate of flow of charge in a circuit. The movement of electrons from negative to positive.

Filament bulb: A light bulb containing a thin wire - a filament - that emits light when current passes through it.

LDR: Light-Dependent Resistor. Resistance decreases as light intensity increases.

LED: Light Emitting Diode. A component that emits light when current flows through in the forward direction. Used in traffic lights, digital clocks, remote controls, etc. No filament that can burn out.

Parallel circuit: A circuit connected with "branches". Voltage is constant over the different branches, but current is split. Allows individual control over components in the circuit.

Resistor: A component that has the sole purpose of opposing and decreasing the current flowing through a circuit.

Series circuit: A circuit where all of the components are connected in one line, and controlled together. Voltage is split across components, but current stays constant.

Thermistor: A resistor dependent on temperature. More heat = Less resistance, Less heat = More resistance. These are useful for temperature detection.

Guide to the most important electrical symbols plus some extra ones:

Section 2 b) Key Words

Alternating current: Current is constantly changing direction

Circuit breaker: An electrical safety device that will trip and break a circuit if too much current is flowing through. Use electromagnets to trip the switch and can be reset.

Conductor: A material that can easily transmit electrical energy, so aqueous/molten ionic compounds and metals, due to the free charged particles allowing current to pass through.

Double insulation: Two layers of insulation of a product, e.g. a plastic coated kettle. Greatly reduces chances of electric shock in event of fault.

Earth wire: Provides a path of least resistance to earth for high voltage currents in event of a fault.

Fuse: A thin wire that will melt when too much current flows through due to heating effect. Electrical safety device, requires replacement.

Insulator: A material that does not transmit electrical energy easily.

Mains electricity: A.c., 230V : the electricity that enters each home.

Resistance: Slows the flow in a circuit down. Causes a heating effect.

Section 2 a) Key Words

Amperes: The unit of measurement for current

Charge: Whether there are more electrons or protons in a substance (negatively charged electrons vs positively charged protons) Positive and negative charges attract each other.

Coulombs: The rate of flow of current

Current: The rate of flow of electrical charge

Ohms: Unit of measurement of resistance

Potential difference: Also called voltage, it is the number of joules per coulomb, or the energy transferred per unit of current flowing per second.

Power: Rate of energy transferred.

Resistance: Anything that slows the flow in a circuit, increased by more components in series.

Voltage: Also called potential difference, it is the number of joules per coulomb, or the energy transferred per unit of current flowing per second.

Volts: Unit of measurement of voltage

Watts: Unit of measurement of power

Section 1 d) Key Words

Artificial Satellite: A man made satellite, put into space by a rocket. Can orbit the Earth, or be put in orbit over another astronomical body.

Comet: Small lumps of icy rock that orbit the Sun. They have elliptical orbits and speed up when they're closer to the Sun as the gravitational strength is stronger.

Galaxy: A collection of billions of stars.

Gravity: The force exerted by all bodies of mass. Causes small bodies to orbit larger ones.

Milky Way: The galaxy we live in.

Moon: A natural satellite. Earth has one moon, known just as "the Moon", however other planets may have many more with individual names.

Orbit: The path one astronomical body takes around another, caused by the force of gravity.

Planet: A body of mass orbiting a star, e.g. the Earth orbiting the sun. It must be of a certain size to be classed as a planet, and have an almost circular, but usually slightly elliptical orbit.

Satellite: A body of mass that orbits another body of mass.

Solar System: The system of planets and comets around our Sun.

Star: A self-luminescent celestial body that produces energy.

Sun: The star at the centre of the Solar System.

Universe: A collection of billions of galaxies. Most of it is empty space. It's huuuuugeeeeeeeeeee

Section 1 c) Key Words

Acceleration: The rate at which the velocity of an object increases. A vector quantity.

Centre of Gravity: The point at which the mass of the object is equal in all directions; the point count be put on a pinpoint and it would not move as all the forces are balanced.

Drag: A force that opposes motion, for example friction or air resistance.

Elastic Limit: The point at which an elastic object is permanently stretched. Beyond this point Hooke's law cannot be applied.

Force: A push or pull on an object due to its interaction with another object, resulting in change of shape, speed, or direction.

Friction: A force opposing motion- happens between two solids e.g. a ball rolled on a carpet.

Hooke's Law: Hooke's law says that extension is proportional to force in an elastic object. As the force applied increases, the extension will increase proportionally.

Magnitude: Size

Mass: How much of an object there is; it has the same value anywhere in the universe

Momentum: How fast an object is going multiplied by its mass- its 'quantity of motion'

Newton's Laws of Motion: 1st law- balanced forces mean no change in velocity
2nd law- a resultant force means acceleration
3rd law- every force has an equal force acting in opposition to it.

Scalar: A quantity that has magnitude (size) but no direction. e.g. mass, distance, speed

Terminal Velocity: When the vertical forces on an object are balanced resulting in a constant speed and no acceleration.

Vector: A quantity that has both magnitude (size) and direction. e.g. weight, displacement, velocity, force

Weight: The force that gravity exerts on matter calculated by multiplying mass by gravity (which is 10 on Earth)

Section 1 b) Key Words

Acceleration: Measurement of how much the speed of an object increases over a length of time
Acceleration = Change in velocity / Time taken

Distance-time graph: A graph used to depict the displacement of an object from the starting point over time. Visual representation of velocity (the gradient)

Velocity-time graph: A graph depicting the speed of an object over time, also used to calculate acceleration by the gradient.

Section 1 a) Key Words

Kilogram (kg): Measurement of mass, 1000 grams

Kilogram metre/second (kg m/s): Standard unit of measurement of momentum

Metre (m): Standard unit of measurement of distance

Metre/second (m/s): Standard unit of measurement of speed or velocity

Metre/second/second (m/s2): Standard unit of measurement of acceleration

Newton (N): Standard unit of measurement of force

Newton per kilogram (N/kg): Standard unit of measurement of gravitational field strength

Second (s): Standard unit of measurement of time

Units: A standard quantity by which other quantities may be expressed in relation to