Ultraviolet (T3)

Question 1

Describe ultraviolet…

Answer 1

• found naturally in sunlight
• we cannot see or feel UV radiation but our skin responds by turning darker
• this happens as our bodies attempt to reduce the amount of UV reaching deeper skin tissues
• darker skin absorbs more UV light, so less UV radiation reaches deeper tissues
• whilst a little is good for you (about 20 mins exposure in a sunny day) too much carries the risk of causing skin cancer
• overexposure at high altitudes (like when skiing or climbing in the Alps) or any exposure to the light from arc welding will cause a painful condition known as snow blindness, or arc eye

Question 2

How was ultraviolet discovered?

Answer 2

• following Herschel’s work, John Ritter (1776 - 1810) tried to find invisible rays at the violet end of the spectrum
• he used silver chloride which turns black when exposed to light
• the happened fastest when exposed to the visible rays at the violet end of the spectrum

Question 3

What are the three main types of ultraviolet radiation and their effects

Answer 3

• UV C
• high frequency
• causes severe damage to cells
• UV B
• high frequency
• causes severe sunburn and damage to cells
• UV A
• low frequency
• weaker effects than UV B

Question 4

List four uses of ultraviolet…

Answer 4

• security marking
• fluorescent lamps
• detecting forged bank notes
• disinfecting water