The Visible Spectrum (T3)

Question 1

What is the visible spectrum and how can you see it?

Answer 1

• using a prism you can split up white light to form a spectrum
• the light waves are refracted as they enter and leave the prism
• the shorter the wave length of the light, the more it is refracted
• as a result, red light is refracted the least and violet light is refracted the most, causing the coloured light to spread out and form a spectrum

Question 2

List three uses of visible light..

Answer 2

• visible light from lasers can read CDs and barcodes
• photography, as visible light can be detected by the sensors in digital cameras
• illumination

Question 3

What are the seven colours in the visible spectrum?

Answer 3

• red
• orange
• yellow
• green
• blue
• indigo
• violet

Question 4

Red light has the …….. wavelength and ……… frequency

Answer 4

Red light has the longest wavelength and lowest frequency

Question 5

Who discovered that white light can be split up into different colours?

Answer 5

Sir Isaac Newton (1642 - 1727)

Question 6

What is dispersion and how does it work?

Answer 6

• when white light passes through a prism it emerges as a band of colours called a spectrum
• each colour travels through the prism at a slightly different speed and the prism has a different refractive index for each colour, so each colour is refracted at a slightly different angle
• this process is known as dispersion