Physics Waves

What is a transverse wave and give three examples?

A wave where oscillations are perpendicular to the direction of energy transfer.

• Electromagnetic waves (light, radio, X-rays).

• Water waves.

• Seismic S-waves.

What is a longitudinal wave and give two examples?

A wave where oscillations are parallel to the direction of energy transfer.

• Sound waves.

• Seismic P-waves.

What happens when a wave is reflected?

It bounces off a surface.

What is the Law of Reflection?

Angle of incidence = Angle of reflection.

What is refraction, and why does it happen?

• When a wave changes direction as it enters a different medium.

• Caused by a change in wave speed.

What is diffraction?

The spreading out of waves when they pass through a gap or around an obstacle.

How do sound waves travel?

As longitudinal waves through a medium (air, water, solids).

Why can’t sound travel in a vacuum?

No particles to carry the wave.

How does sound change in different materials?

• Travels faster in solids than in liquids or gases.

• Travels slowest in gases.

What happens to sound when frequency increases and what happens when amplitude increases?

Frequency: The pitch increases.

Amplitude: The loudness increases.

What are P-waves?

• Primary waves – longitudinal.

• Faster than S-waves.

• Travel through solids and liquids.

What are S-waves?

• Secondary waves – transverse.

• Slower than P-waves.

• Travel only through solids.

How do seismic waves provide evidence for the Earth's structure?

• S-waves can’t travel through liquids, proving Earth’s outer core is liquid.

• P-waves bend (refract) at boundaries, showing layers inside Earth.

What are electromagnetic waves?

Transverse waves that transfer energy and can travel through a vacuum.

What are the three common features of all electromagnetic waves?

• They are transverse waves.

• They travel at the same speed in a vacuum (3 × 10⁸ m/s).

• They can travel through a vacuum (don’t need a medium).

List the EM spectrum in order of increasing frequency and decreasing wavelength.

• Radio waves

• Microwaves

• Infrared (IR)

• Visible light

• Ultraviolet (UV)

• X-rays

• Gamma rays

What are radio waves used for?

Communication (TV, radio).

What are microwaves used for?

• Cooking.

• Satellite communication.

What is infrared (IR) radiation used for?

• Thermal imaging.

• Remote controls.

What is visible light used for?

• Optical fibers.

• Photography.

What is ultraviolet (UV) radiation used for?

• Sterilizing medical equipment.

• Detecting forgeries.

What are X-rays used for?

Medical imaging (seeing bones).

What are gamma rays used for?

Cancer treatment (radiotherapy).

What are the dangers of X-rays and gamma rays?

Can cause mutations, which could lead to cell damage and cancer.

What is a perfect black body?

An object that absorbs and emits all radiation perfectly.

How does temperature affect radiation emission?

• Higher temperature = More radiation emitted.

• Higher temperature = Shorter wavelength radiation emitted.