Refraction of a Wave of Light

A light wave in a vacuum travels at 300,000 kilometres (km) per second! Or to be exact, 299,792 km/sec.

300,000 kilometres per second.

Yes! As light crosses the boundary from a faster medium to a slower medium it bends towards the normal.

The wavelength of an electromagnetic wave is a measurement of the length of a single oscillation of the wave.

Red and orange are two of the colours in the visible spectrum with the longest wavelengths.

The angle of refraction measures the angle to which light bends as it passes across the boundary between different media.

• The angle of refraction is measured between a ray of light and an imaginary line called the normal.
• In optics, the normal is a line drawn on a ray diagram perpendicular to, so at a right angle to (90⁰), the boundary between two media.
• See this diagram for an explanation: Refraction of a ray of light
• If the boundary between the media is curved, the normal is drawn perpendicular to the boundary.

In physics and optics, a medium refers to any material through which light or other electromagnetic waves can travel. It’s essentially a substance that acts as a carrier for these waves.

• Light is a form of electromagnetic radiation, which travels in the form of waves. These waves consist of oscillating electric and magnetic fields.
• The properties of the medium, such as its density and composition, influence how light propagates through it.
• Different mediums can affect the speed, direction, and behaviour of light waves. For instance, light travels slower in water compared to a vacuum.
• Examples of Mediums:
  • Transparent: Materials like air, glass, and water allow most light to pass through, with minimal absorption or scattering. These are good examples of mediums for light propagation.
  • Translucent: Some materials, like frosted glass or thin paper, partially transmit light. They allow some light to pass through while diffusing or scattering the rest.
  • Opaque: Materials like wood or metal block light completely. They don’t allow any light to travel through them.

The frequency of electromagnetic radiation (light) refers to the number of wave-cycles of an electromagnetic wave that pass a given point in a given amount of time.

• Frequency is measured in Hertz (Hz) and signifies the number of wave-cycles per second. Sub-units of Hertz enable measurements involving a higher count of wave-cycles within a single second.
• The frequency of electromagnetic radiation spans a broad range, from radio waves with low frequencies to gamma rays with high frequencies.
• The wavelength and frequency of light are closely linked. Specifically, as the wavelength becomes shorter, the frequency increases correspondingly.
• It is important not to confuse the frequency of a wave with the speed at which the wave travels or the distance it covers.
• The energy carried by a light wave intensifies as its oscillations increase in number and its wavelength shortens.

Incident light refers to light that is travelling towards an object or medium.

• Incident light refers to light that is travelling towards an object or medium.
• Incident light may come from the Sun, an artificial source or may have already been reflected off another surface, such as a mirror.
• When incident light strikes a surface or object, it may be absorbed, reflected, refracted, transmitted or undergo any combination of these optical effects.
• Incident light is typically represented on a ray diagram as a straight line with an arrow to indicate its direction of propagation.

Wavelength measures a complete wave cycle, which is the distance from any point on a wave to the corresponding point on the next wave.

• While wavelength can be measured from any point on a wave, it is often simplest to measure from the peak of one wave to the peak of the next or from the bottom of one trough to the bottom of the next, ensuring the measurement covers the whole of the cycle.
• The wavelength of an electromagnetic wave is usually given in metres.
• The wavelength of visible light is typically measured in nanometres, with 1,000,000,000 nanometres making up a metre.
• Radio waves, visible light, and gamma waves for example, each have different ranges of wavelengths within the electromagnetic spectrum.

The angle of incidence measures the angle at which incoming light strikes a surface.

• The angle of incidence is measured between a ray of incoming light and an imaginary line called the normal.
• See this diagram for an explanation: Reflection of a ray of light
• In optics, the normal is a line drawn on a ray diagram perpendicular to, so at a right angle to (90⁰), the boundary between two media.
• If the boundary between the media is curved, then the normal is drawn at a tangent to the boundary.

A wave diagram is a graphic representation, using specific drawing rules and labels, that depicts variations in the characteristics of light waves. These characteristics include changes in wavelength, frequency, amplitude, speed of light and propagation direction.

• A wave diagram provides a visual representation of how a wave behaves when interacting with various media or objects.
• The purpose of a wave diagram is to illustrate optical phenomena, including reflection, refraction, dispersion, and diffraction.
• Wave diagrams can be useful in both theoretical and practical applications, such as understanding the basics of the physics of light or when designing complex optical systems.