Difference Between Electromagnetic Wave Theory and Planck's Quantum Theory l Electromagnetic Wave Theory vs Planck's Quantum Theory

The key difference between Electromagnetic Wave Theory and Planck’s Quantum Theory is that the Electromagnetic Wave Theory does not explain the black body radiation phenomena and photoelectric effect whereas Planck’s Quantum Theory does explain the black body radiation phenomena and the photoelectric effect.

If we heat a substance (which has a high melting point), it first turns red coloured, then converts into a yellow colour, which then begins to glow with white and blue light. Once the substance is heated like this, we call it a “black body” and the resulting radiation (that the substance emits) is “black body radiation”. However, we cannot explain how this happens using electromagnetic wave theory but the Planck’s quantum theory explains it well.

CONTENTS

1. Overview and Key Difference
2. What is Electromagnetic Wave Theory
3. What is Planck’s Quantum Theory
4. Side by Side Comparison – Electromagnetic Wave Theory vs Planck’s Quantum Theory in Tabular Form
5. Summary

What is Electromagnetic Wave Theory?

Electromagnetic Wave Theory is a theory in chemistry that was developed by James Clark Maxwell in 1864. According to this theory, there are several points about radiation emitted from a substance.

These points are as follows:

• Energy emits from any source continuously in the form of radiant energy.
• Radiation has two fields oscillating perpendicular to each other; electric field and magnetic field. Both these fields are perpendicular to the path of radiation.
• Radiation has wave characteristics and travels in the velocity of light. We call it electromagnetic radiation.
• These electromagnetic radiation does not require matter for propagation.

The “wave” described in this theory has several characteristics. The wavelength of the wave is the distance between two consecutive crests or troughs of the wave. A number of waves that pass through a point per one second are the frequency of the wave. The linear distance that the wave travels per one second is the velocity. Wavenumber is the number of waves present in one-centimetre length.

Figure 01: Electromagnetic Wave Length