Key terms & definitions

A device that detects when an interrupt card passes through a light beam, allowing time and velocity to be measured without human reaction-time delay.

A device that detects when an object interrupts a light beam, allowing its motion to be timed electronically.

A feeling of dizziness or faintness.

Industries producing consumer goods, such as clothing, rather than heavy industrial products such as steel.

The strength of a light, affecting how brightly it illuminates a subject or setting.

The amount of light reaching a given area in a given time.

The amount of light reaching a given area; greater light intensity means brighter illumination at the LDR.

The amount of light reaching a given area per unit time.

A laboratory instrument that uses visible light and lenses to produce a magnified image of a small specimen.

A microscope that uses light and lenses to produce a magnified image of a specimen.

A large electrostatic spark caused by a build-up of charge in storm clouds and a sudden transfer of charge.

A nucleus with relatively few protons and neutrons and therefore a relatively small mass.

A strong substance deposited in xylem walls that strengthens the tubes and helps prevent them from collapsing.

A material that strengthens the walls of xylem vessels and helps support the plant.

A substance in wood that binds fibres together; chemical pulping removes it to release the fibres.

Charges of the same type: either both positive or both negative.

A response scale recording degrees of agreement with a statement, usually from strongly disagree to strongly agree.

A rating scale on which participants indicate their degree of agreement with a statement.

Terms with the same surd part after simplification, such as $3\sqrt{5}$ and $8\sqrt{5}$.

Terms with the same surd part and the same variables raised to the same powers, so their coefficients can be collected.

Terms with exactly the same letters raised to the same powers, although their numerical coefficients may differ.

Terms with exactly the same variable part, including the same letters raised to the same powers.

A group of interconnected brain structures involved in emotion; its activation helps explain the emotional content of dreams.

A sedimentary rock made mainly of calcium carbonate.

A sedimentary rock made mainly of calcium carbonate, often formed from the accumulated shells and skeletons of marine organisms.

An aqueous solution of calcium hydroxide used to test for carbon dioxide.

A solution of calcium hydroxide in water, used to test for carbon dioxide gas.

A reason why evidence cannot fully answer a particular historical question.

A weakness or boundary of a model that prevents it from representing or explaining some feature of reality.

Protection that limits shareholders’ financial responsibility for company debts to their investment in its shares.