A human observer is a person who engages in observation by watching things.
- In the presence of visible light, an observer perceives colour because the retina at the back of the human eye is sensitive to wavelengths of light that fall within the visible part of the electromagnetic spectrum.
- The visual experience of colour is associated with words such as red, blue, yellow, etc.
- The retina’s response to visible light can be described in terms of wavelength, frequency and brightness.
- Other properties of the world around us must be inferred from light patterns.
- An observation can take many forms such as:
- Watching an ocean sunset or the sky at night.
- Studying a baby’s face.
- Exploring something that can’t be seen by collecting data from an instrument or machine.
- Experimenting in a laboratory setting.