Physics

Physics

Problem

Which one of the following quantities, when multiplied by Planck’s constant, gives the energy of a single photon? a) Threshold frequency of the metal, ν0\text{Threshold frequency of the metal, }\nu_0 b) Frequency of light, ν\text{Frequency of light, }\nu c) Angular frequency of light, ω\text{Angular frequency of light, }\omega d) Beat frequency between two light beams, Δν\text{Beat frequency between two light beams, }\Delta\nu
Intuitive explanation

The key insight is recognizing that Planck's equation E=hνE = h\nu connects energy to a fundamental property of light's oscillation. You need to identify which quantity—frequency, wavelength, or period—is the one that, when multiplied by hh, directly yields a photon's energy. Think about what hh is dimensionally designed to pair with: it has units of energy × time, so it "wants" to multiply something with units of inverse time.

Intuitive explanation

The key insight is recognizing that Planck's equation E=hνE = h\nu connects energy to a fundamental property of light's oscillation. You need to identify which quantity—frequency, wavelength, or period—is the one that, when multiplied by hh, directly yields a photon's energy. Think about what hh is dimensionally designed to pair with: it has units of energy × time, so it "wants" to multiply something with units of inverse time.

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