1. Module 6

1.6. Page 4

Lesson 1

Module 6—Wave-Particle Duality and Quantum Physics

 

Lesson Summary

 

In this lesson you focused on the following questions:

  • How is blackbody radiation illustrated graphically?

  • What is the relationship between colour and temperature?

  • What are a quantum and a photon?

In this lesson you learned that a blackbody refers to a hypothetical object that absorbs all of the electromagnetic radiation that falls on it. The absorbed energy causes the blackbody to heat up and become a perfect radiator, emitting energy back to the environment in the form of electromagnetic radiation. The intensity and wavelength (or frequency) of the emitted radiation can be used to construct a blackbody radiation curve. Such curves illustrate the emitted energy distribution in terms of wavelength (or frequency) versus intensity for a blackbody at various temperatures. The curves showed that as the temperature increased, the frequency and intensity of the emitted EMR also increased. Attempts to explain this using classical physics gave nonsensical solutions.

 

You also learned that the radiation curve can be explained by assuming that energy is emitted from hot objects in discrete bundles, or photons, each capable of transferring a minimum quanta of energy associated with its wavelength and frequency according to Planck’s formula, E = hf. Applying the formula to the electromagnetic spectrum reveals the energy of the photons in all the general classifications of the spectrum.

 

You also learned that for physics in general, the idea of the quantum marked the end of classical physics and the beginning of quantum physics by showing that light could be considered a photon, a particle.

 

Lesson Glossary

 

blackbody: any object that absorbs all EMR that falls on it and is capable of being a perfect emitter, releasing energy in the form of EMR

 

blackbody radiation curve: a graph of the intensity of EMR versus wavelength for an object at a given temperature

 

incandescent: glowing with heat

 

quantum (pl. quanta): the smallest bundle or packet of energy that a given wavelength or frequency of EMR can possess

 

photon: one quantum of light

 

Planck’s formula: EMR energy is the product of the number of quanta, Planck’s constant, and the frequency of the radiation