Open up your notes at page 9, note 15 ,Electromagnetic family – Names and Applications. Collect a highlighter or coloured pen.

wavelengthsdiffracting

TV

Radio waves have longer wavelengthsthan TV, so radio waves diffract better than TV

satellitesMicrowaves are one of the electromagnetic waves that can go up through the atmosphere around the earth without being reflected back to earth. They can also re-enter without any problems.

heat

muscledry

thermal

Police helicopters are fitted with thermal imaging cameras.This allows them to track people on the ground, even whenthey think they are hiding.Hospitals use thermographs to detect areas of infection or tumours. These areas are hotter thanthe rest of the body so show up as a differentcolour.

colours

longerlaser

birth tattoosvaporise

Jump to note (5) on page 10 of the notes.

sunheat burn

cancer

acne fluorescent

securityultra-violet

black

bones

photographs

slices3

cancerous

injectedgamma

bloodtracer

Go back to page 10 of the notes.

f = 2870 MHz = 2870 000 000 Hz v = 3 x 108 ms-1 l = ?

l = v f = 3 x 108 2 870 000 000 = 0.1045296167247387 m TOO MANY SIG FIGS.

SO 0.1 or 0.105 m is acceptable

t = ? v = 3 x 108 ms-1 d = 980 km = 980 x 103 m

t = d v = 980 x 103

3 x 108

= 0.0032666666666…. s HAS TOO MANY SIG. FIGS,

SO….0.0033 s or 3.3 x 10 -3 s

Problems, page 23 and 24.Then problems on pages 25 and 26.