Lecture Notes: Light, Photons, and the Electromagnetic Spectrum

A set of question-and-answer flashcards covering key concepts from the lecture notes on light, waves, photons, Planck's constant, the photoelectric effect, and the electromagnetic spectrum.

What is the speed of light and its symbol?

c ≈ 3.0 × 10^8 m/s.

Define wavelength and its symbol.

Wavelength, lambda (λ), is the distance between identical points on successive waves (e.g., peak to peak).

Define frequency and its symbol.

Frequency, nu (ν), is the number of cycles per second, measured in hertz (Hz, s^-1).

What is the relationship between wavelength, frequency, and the speed of light?

ν = c/λ; λ = c/ν; c = λν.

What are the units for wavelength?

Meters or nanometers; 1 nm = 1.0 × 10^-9 m.

What is the amplitude of a light wave?

The height of the wave; larger amplitude corresponds to brighter light.

What is the electromagnetic spectrum and order of regions from low to high frequency?

Radio, microwave, infrared, visible, ultraviolet, X-ray, gamma; frequency increases from left to right.

What does ROYGBIV stand for?

Red, Orange, Yellow, Green, Blue, Indigo, Violet.

What is wave-particle duality?

Light exhibits both wave-like and particle-like properties; photons carry energy in quanta.

What is Planck's constant and its approximate value?

h ≈ 6.626 × 10^-34 J·s (often rounded to ~7 × 10^-34 for quick calculations).

What is the energy of a photon?

E = hν = hc/λ; energy carried by a single photon.

What is the photoelectric effect?

Emission of electrons from a metal when illuminated with light of sufficient photon energy; electrons emitted only if Ephoton > φ (work function); kinetic energy is Ephoton − φ.

What is φ (phi) in the photoelectric effect?

The work function or threshold energy required to eject an electron from the surface.

How do you convert 600 nm to meters?

600 nm = 600 × 10^-9 m = 6.0 × 10^-7 m.

How do you find frequency from wavelength?

Use ν = c/λ; plug λ in meters.

How do you find wavelength from energy E?

λ = hc/E.

What is the energy of a photon in terms of wavelength?

E = hc/λ.

How is energy related to wavelength and frequency when solving problems?

Energy is proportional to frequency (E = hν) and inversely proportional to wavelength (E = hc/λ).

What is the significance of c's units?

c has units of meters per second, used to relate wavelength and frequency.

When dividing powers of ten, how do exponents combine?

Exponents add when multiplying, and subtract when dividing; 10^a / 10^b = 10^(a−b).