What are electromagnetic waves?
Waves that do not require a material medium and arise from vibrations of electric and magnetic fields.
How are the electric and magnetic fields oriented in an electromagnetic wave?
They are perpendicular to each other and to the direction of propagation.
Give two examples of electromagnetic waves.
Light waves, X-rays, gamma rays.
How do electromagnetic waves differ from mechanical waves?
EM waves travel at the speed of light and are always transverse; mechanical waves can be transverse or longitudinal.
Define wavelength.
The distance between identical points on consecutive cycles, such as crest to crest.
Define frequency.
The number of wave crests passing a point per second.
What is the relationship between wavelength and frequency?
Shorter wavelengths correspond to higher frequencies.
Write the equation relating wavelength, frequency, and speed of light.
$$ \lambda = \frac{c}{f} $$
Who predicted the existence of electromagnetic waves?
James Clerk Maxwell.
Who provided experimental evidence for EM waves?
Heinrich Hertz.
Name the seven groups in the electromagnetic spectrum.
Gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, radio waves.
List two properties shared by all electromagnetic waves.
Reflection, refraction, interference, diffraction.
What are radio waves used for?
Communication systems such as radios and televisions.
Give two uses of infrared radiation.
Industrial drying, muscle treatment, thermal imaging.
What is the primary source of visible light?
The Sun.
What are ultraviolet rays used for?
Sterilization and fluorescence.
How are X-rays produced?
By striking metal with fast-moving electrons.
What are gamma rays used for?
Cancer treatment and nuclear industry applications.
How are gamma rays detected?
Using a Geiger–Müller tube.
How are radio waves detected?
Radio sets, television sets, and aerials.
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