Waves and Their Applications in Technologies for Information Transfer
What you must know
A wave carries energy without carrying matter along with it. Know the anatomy of a wave: wavelength, frequency, amplitude, and speed, and the relationship speed = frequency × wavelength. Frequency is measured in hertz (waves per second). Higher frequency means shorter wavelength when speed is constant.
Distinguish mechanical waves (need a medium, such as sound) from electromagnetic waves (travel through space, such as light and radio). Sound travels faster in solids than in gases; light travels far faster than sound, which explains seeing lightning before hearing thunder. Understand reflection, refraction (bending as speed changes between media), and absorption. In the electromagnetic spectrum, radio, microwave, infrared, visible, ultraviolet, X-ray, and gamma rays differ by frequency and energy.
Connect waves to technology: digital signals encode information as discrete values, are less affected by noise, and can be transmitted and stored reliably; analog signals vary continuously. Fiber optics use light reflection; radios and phones use electromagnetic waves.
Traps to watch
- Waves transfer energy, not matter, through the medium.
- Changing amplitude changes loudness or brightness, not pitch or color.
- Refraction is bending due to speed change, not reflection.
- Sound cannot travel through a vacuum; light can.
Rule of thumb
Use v = f × λ. If v is fixed and f rises, λ must fall. For signal questions, ask whether the value is continuous (analog) or discrete (digital).
Worked example
A wave with frequency 50 Hz and wavelength 4 m has speed 50 × 4 = 200 m/s. If the same medium carries a 100 Hz wave, its wavelength is 2 m.