Circuits Waves and Particles Y9 S2 T4

Current (A)

Flow of electrical charge.

Voltage (V)

Energy supplied by the battery.

Ammeter

Measures current (connected in series).

Voltmeter

Measures voltage (connected in parallel).

Energy and Current Rule

Energy is transferred, not used up. Current is not used up.

Series Circuit Pathways & Current

One pathway with the same current throughout.

Series Circuit Voltage & Failures

Voltage is shared between components; if one bulb breaks, all go out.

Parallel Circuit Pathways & Voltage

Multiple pathways where each branch gets full voltage.

Parallel Circuit Failures & Brightness

If one bulb breaks, others stay on; bulbs are brighter than in series.

Wave

Transfers energy without transferring matter overall.

Amplitude

Height of wave → determines loudness.

Frequency (Hz)

Waves per second → determines pitch.

Wavelength (λ)

Distance between two crests.

Reflection

Bounces off a surface.

Refraction

Changes direction in a new medium.

Diffraction

Bends around obstacles or openings.

Absorption

Energy taken in by a material.

Electromagnetic Spectrum Order

Radio → Microwave → Infrared → Visible Light → UV → X-ray → Gamma

Electromagnetic Waves Properties

Transfer energy and can travel through a vacuum.

Radio Waves Use

Used for communication.

Sound Waves Properties

Transfer kinetic/potential energy through a medium (air, water, solids) without transferring matter; reflect, refract, and diffract.

Conduction (Heat)

Heat transferred by direct contact (best in metals).

Convection (Heat)

Heat transferred in liquids and gases (warm particles rise, cool particles sink).

Radiation (Heat)

Heat transferred by electromagnetic waves with no particles needed (e.g., Sun warming Earth).

Particle Model Basics

All matter is made of tiny particles that are always moving, have spaces between them, and move faster when heated.

Solids (Particle Model)

Particles tightly packed, vibrate in fixed positions, fixed shape and volume.

Liquids (Particle Model)

Particles close together, move past each other, fixed volume, no fixed shape.

Gases (Particle Model)

Particles far apart, move freely and quickly, no fixed shape or volume.

Heating Matter

Particles gain kinetic energy, move faster, and temperature increases.

Cooling Matter

Particles lose kinetic energy, move slower, and temperature decreases.

Independent Variable

The variable changed by the scientist.

Dependent Variable

The variable measured or observed.

Controlled Variable

Variables kept the same for a fair test.

Graph/Table Trend Words

Increase, decrease, remain constant, rise rapidly, level off.