Edexcel GCSE Physics key terms

A small compass used to find the direction of a magnetic field at a particular position.

Thomson’s model of an atom as a sphere of positive charge with negative electrons embedded throughout it.

An idealised charged object whose size is negligible compared with the distances being considered.

Which of two terminals is at the higher potential; reversing the polarity reverses the sign of the measured voltage.

An overall charge caused by an object having fewer electrons than protons.

A positively charged particle; in a metal, positive ions occupy fixed positions in a lattice but can vibrate.

A positively charged ion, formed when an atom or group of atoms loses one or more electrons.

The antiparticle of an electron: it has the same mass as an electron but a positive charge.

A medical imaging technique that detects radiation resulting from positron-emitting radiotracers inside the body.

The possibility that electromagnetic radiation could cause harm; the actual risk also depends on the exposure.

The energy transferred per unit charge between two points, measured in volts.

The energy transferred per unit charge between two points, measured in volts (V).

Energy stored because of the positions of particles relative to one another and the forces between them.

The rate at which energy is transferred or work is done.

A factor written as $10$ raised to a power, used to describe the scale of a quantity.

The rate at which an appliance transfers energy when it is operating normally, usually stated in watts or kilowatts.

The closeness with which a value is stated, often indicated by its number of significant figures or decimal places.

A symbol placed before a unit to show that the unit has been multiplied by a particular power of ten.

Force acting normally per unit area, measured in pascals (Pa).

The change in pressure between two positions, measured in pascals (Pa).

A relationship for a fixed mass of gas at constant temperature in which pressure multiplied by volume remains constant: $P_1V_1=P_2V_2$.

The coil connected to the input supply of a transformer.

The straight reference line passing through the optical centre and the principal foci of a lens.

The point where rays initially parallel to the principal axis meet, or appear to come from, after passing through a lens.

The rule that, when rotational forces are in equilibrium, the total clockwise moment about a pivot equals the total anticlockwise moment about that pivot.

A positively charged subatomic particle found in an atom's nucleus.

A forming star produced when gravity draws material together, causing it to become denser and hotter.