Waves, Electromagnetic Radiation, and Photons (Lecture Flashcards)

Flashcards covering the wave nature of matter, electromagnetic spectrum, photon energy, the photoelectric effect, absorbance, and key constants.

What is the fundamental equation that relates the speed of light (c), wavelength (λ), and frequency (ν)?

c = λ × ν (the product of wavelength and frequency equals the speed of light).

What symbol is used for wavelength in these notes?

λ (lambda).

What symbol is used for frequency in these notes?

ν (nu).

What is the commonly used rounded value of the speed of light in calculations?

c ≈ 3 × 10^8 m/s.

What is the unit for frequency?

s⁻¹, or Hz (hertz).

What is the formula for the energy of a photon in terms of frequency?

E = hν (Planck's relation).

What is Planck's constant and its approximate value used in class?

h ≈ 6.626 × 10⁻³⁴ J·s.

What is the relationship that gives photon energy in terms of wavelength instead of frequency?

E = hc/λ.

What is the minimum energy required to eject an electron from a metal surface called?

The work function (φ).

In the photoelectric effect, what happens if the photon energy exceeds the work function?

An electron is ejected; the excess energy appears as the electron's kinetic energy, KE = hν − φ.

What is a photon?

The quantum particle of light that carries energy E = hν.

What is the approximate range of wavelengths that make up visible light?

About 400–800 nm.

Which region of the electromagnetic spectrum is associated with vibrational transitions of bonds in molecules?

Infrared (IR) radiation.

What did Newton demonstrate by passing white light through a prism?

White light is a mixture of colors and can be dispersed into a spectrum of colors.

What is the visible color order from red to violet commonly recalled?

Red, Orange, Yellow, Green, Blue, Indigo, Violet (ROYGBIV).

What happens to energy as wavelength becomes shorter (e.g., from infrared to visible to ultraviolet)?

Frequency increases; energy per photon increases (E = hν).

What is the relationship between frequency and wavelength in the electromagnetic spectrum as wavelength decreases?

ν = c/λ; as wavelength decreases, frequency increases.

Which type of EM radiation has the highest energy per photon?

Gamma rays.

What is the term for the discrete units of energy proposed by Planck that explain photon energy?

Quanta (quantum); E = hν = hc/λ.

What is the equation used to calculate the energy of a yellow photon (λ ≈ 589 nm)?

E = hc/λ; for λ = 589 nm, E ≈ 3.4 × 10⁻¹⁹ J per photon.

What is absorbance (A) directly related to in spectrophotometry?

Concentration of the absorbing species (Beer-Lambert law).

Which modulation technique changes the frequency of the carrier wave in radio transmission?

Frequency Modulation (FM).

Which modulation technique varies the amplitude (height) of the carrier wave to encode information?

Amplitude Modulation (AM).

Which region of electromagnetic radiation is associated with bond vibrations and heat sensing?

Infrared (IR) radiation.

Which region of EM radiation can ionize inner-shell electrons and penetrate soft matter more than UV?

X-ray radiation.

Which high-energy radiation can split atomic nuclei at very high energies?

Gamma-ray radiation.