P1 Topic 2

Página 1

Physics P1 Topic 2

2.1 - Herschel

William Herschel, Put coloured filters on telescope, some heated telescope more than others, Used prism to break up visible light, found thermometer reading went higher from violet to red, put thermometer past red, discovered Infrared radiation.

2.1 - Ritter

Johan Ritter looked at opposite end of spectrum, silver chloride turns black when exposed to light, turned black fastest past violet on spectrum, discovered ultraviolet radiation.

2.2

All electromagnetic waves are transverse, all travel at 3x10^8 m/s in a vacuum

2.3

Radiowaves, Microwaves, Infrared, Visible (ROYGBIV), Ultraviolet, x-rays, Gamma

Increased frequency, decreasing wavelength, increasing energy ----->

2.4

Electromagnetic spectrum is continuous from radiowaves to gamma rays in order of increasing frequency and decreasing wavelength

2.5

Danger increases as frequency increases

2.6 - Dangers

Microwaves: Internal heating of body cells, targets water

Infrared: Skin burns

Visible light: Can cause eye damage with over exposure, Blindness

Ultraviolet: Damage to surface cells and eyes, can lead to skin cancer and eye conditions

X Rays and Gamma Rays: Mutation or damage to cells in the body, leads to cancer

2.7 - Uses

Radiowaves: Broadcasting, communications, satellite transmissions

Microwaves: Cooking, Communications, Satellite transmissions

Infrared: Cooking, thermal imaging, television remote controls, security systems, optical fibres, short range communications

Visible light: Vision, Photography, illumination

Ultraviolet: Security marking, fluorescent lamps, disinfecting water, recognising forged bank notes

X-Rays: Observing internal structure of objects, security scanners, Medical x-rays

Gamma Rays: Sterilising food and medical equipment, detection of cancer and it's treatments

2.8

Ionising radiations are emitted all the time by radioactive sources

2.9

Ionising radiation includes Alpha and Beta particles, Gamma rays, which all transfer energy