Wave Mastery
A wave has a frequency of 25 Hz. How many complete waves pass a point in 4 seconds?
Answer: 100 waves
Which has a shorter wavelength: X-rays or ultraviolet?
X-rays
What happens to the amplitude of a wave if it transfers more energy?
The amplitude increases — waves with greater amplitude carry more energy.
Which EM wave is used in TV remote controls?
Infrared
Two waves travel through the same medium at the same speed. Wave A has a higher frequency than Wave B. Which has the shorter wavelength?
Wave A
Why can radio signals from a spacecraft travel through the vacuum of space?
Radio waves are electromagnetic waves and do not require a medium.
A student shakes one end of a rope faster but does not change the medium. What happens to the frequency, speed and wavelength?
Frequency increases, speed remains approximately constant, and wavelength decreases.
Doctors want radiation that can penetrate soft tissue but is absorbed more strongly by bone. Which EM wave should they use and why?
X-rays, because they penetrate soft tissue more effectively while being absorbed more strongly by dense bone.
Explain how a sound wave can transfer energy across a classroom even though the air particles themselves do not travel from the speaker to the listener.
Air particles vibrate back and forth around their resting positions, transferring energy to neighbouring particles. Energy moves through the medium without a net transfer of particles.
Put these in order from lowest energy to highest energy:
Ultraviolet – Radio – Gamma – Infrared – X-ray
Answer: Radio → Infrared → Ultraviolet → X-ray → Gamma