Understanding Wave Properties
Every wave has key features you need to know. Amplitude is how big the wave is - think of it as the height of a water wave or how loud a sound is. Wavelength measures the distance between two identical points on neighbouring waves, whilst frequency tells you how many waves pass by each second.
Waves come in two main types. Transverse waves wiggle up and down whilst moving forward - like waves on water or light waves. Longitudinal waves push and pull in the same direction they're travelling - sound waves work this way, creating squeezed areas called compressions and stretched areas called rarefactions.
When waves hit objects, three things can happen: they absorb (energy gets soaked up), transmit (pass straight through), or reflect (bounce back). Refraction occurs when waves change direction as they enter different materials - like how a straw looks bent in water.
Quick Tip: Remember that frequency and period are opposites - high frequency means short time between waves!
Measuring Sound Speed and Wave Calculations
You can actually measure how fast sound travels using a simple experiment. Stand a known distance from a large building, fire a starting pistol, and time how long the echo takes to return. Since the sound travels to the building and back, you'll need to halve your time measurement before calculating speed.
The most important equation you'll use is: wave speed = frequency × wavelength . This works for all types of waves and connects the three key measurements you'll encounter in exams.
Exam Success: Always check your units - wave speed in m/s, frequency in Hz, and wavelength in metres.
The Electromagnetic Spectrum
The electromagnetic spectrum includes all types of light and radiation, from radio waves to gamma rays. They're all transverse waves travelling at an incredible 300,000,000 m/s through space. As you move across the spectrum, wavelengths get shorter and frequencies increase.
Some electromagnetic waves are dangerous because they're ionising - they carry enough energy to damage your DNA and potentially cause cancer. The higher the frequency, the more dangerous they become. Radio waves and microwaves are generally safe, but ultraviolet, X-rays, and gamma rays require careful handling.
Different waves have specific uses: radio waves for broadcasting, microwaves for cooking and satellites, infrared for heating, visible light for fibre optics, ultraviolet for sterilisation, X-rays for medical imaging, and gamma rays for cancer treatment.
Real World: Your mobile phone uses multiple parts of the electromagnetic spectrum - radio waves for calls, microwaves for WiFi, and visible light for the screen!