Light

Order the EM spectrum from longest λ → shortest λ.

Radio → Microwave → Infrared → Visible → Ultraviolet → X-rays → Gamma

Which has the longest wavelength? Which has the shortest?

Longest = Radio. Shortest = Gamma.

Visible light wavelength range (approx).

~400 nm (violet) to ~750 nm (red).

Match color → approx wavelength (nm).

Red 750, Orange 650, Yellow 600, Green 550, Blue 500, Indigo 450, Violet 400.

Relationship between λ, ν, and E.

λ ∝ 1/ν and E ∝ ν. So longer λ → lower ν → lower E; shorter λ → higher ν → higher E.

What is interference?

When two or more waves overlap and combine — they can add or cancel.

Constructive interference — what and when?

Waves in phase → amplitudes add → stronger signal.

Destructive interference — what and when?

Waves out of phase → amplitudes subtract or cancel → weaker or zero signal.

Two equal waves 180° out of phase — result?

Complete destructive interference (they cancel).

Which parts of the spectrum are ionizing?

High-energy UV (upper UV), X-rays, and Gamma rays — can remove electrons.

Quick uses: what are X-rays and radio commonly used for?

X-rays = medical imaging; Radio = communication, broadcasting.

Mnemonic to remember order (opinionated):

“Really Mad In Vegas, Uber Xtra Gutsy” → Radio, Microwave, Infrared, Visible, Ultraviolet, X-ray, Gamma