a) EM waves

a) electromagnetic spectrum; properties of electromagnetic waves

b) orders of magnitude of wavelengths of the principal radiations from radio waves to gamma rays

EM wave = an electric and magnetic field oscillating perpendicular to each other

EM waves

• are transverse

• can be reflected

• can be refracted

• can be diffused

• can be plane polarised

• can travel through vacuums → at a speed of 3 × 10⁸ms^-1

EM spectrum, wavelengths, and frequencies

• radio waves → 10³, 10^4

• microwaves → 10^-2, 10^8

• infrared → 10^-5, 10^12

• visible → 10^-6, 10^15

• ultraviolet → 10^-8, 10^16

• x-rays → 10^-10, 10^18

• gamma rays → 10^-12, 10²0