Light: Wave, Particle, or Both?
The strange nature of light
Wave behavior
Light shows wave-like behavior in interference and diffraction. When light passes through two slits, it can create a pattern of bright and dark bands, which is characteristic of waves.
Particle behavior
Light also behaves like a stream of particles called photons. In the photoelectric effect, energy arrives in separate packets rather than spreading continuously.
Wave-particle duality
Quantum physics does not say light is sometimes a wave and sometimes a particle in a simple classical sense. Instead, light is described by a quantum object that can show wave-like and particle-like properties depending on how it is measured.
Helpful analogy
Think of quantum theory as expanding the meaning of 'wave' and 'particle' rather than choosing one ordinary picture forever.
Photons
A photon is a quantum of light. Its energy depends on frequency according to , and its momentum is related to wavelength. Higher-frequency light carries more energy per photon.
What experiment is famous for demonstrating interference of light?
The double-slit experiment produces a pattern that shows wave interference.
Correct answer: The double-slit experiment
What do we call a particle of light?
A photon is the quantum particle associated with light.
Correct answer: Photon
How to think about light in quantum physics
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Step 1: Observe that light can interfere like a wave.
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Step 2: Notice that energy arrives in discrete packets.
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Step 3: Use the photon concept to describe light quanta.
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Step 4: Accept that measurement reveals different aspects of the same quantum object.