1.3 - photons

EM wave spectrum

ron de spectrum ?

which em wave has the shortest wavelength ?

gamma

which em wave has the longest wavelength ?

radio

which em wave has the highest frequency ?

gamma

which em wave has the lowest frequency ?

radio

which em wave has the highest energy ?

gamma

which em wave has the lowest energy ?

radio

what is the wavelength range of radio?

> 0.1m

what is the wavelength range of microwave ?

0.1m - 1mm

what is the wavelength range of infrared ?

1mm - 700nm

what is the wavelength range of visible light ?

700nm - 400nm

what is the wavelength range of UV ?

400nm - 1nm

what is the wavelength range of x-ray ?

10nm - 0.001nm

what is the wavelength range of gamma ?

< 1nm

what speed do EM waves travel in a vacuum?

the speed of light, 3 × 10^8 ms^-1

which EM waves travel at the speed of light when in a vacuum?

they ALL do … fuck man.. you’re so stupid ..

fuck you

turn over 4 surprise :3

wave speed equation

c = fλ

c - wave speed

f - frequency

λ - wavelength

EM waves

• an electric and magnetic wave which travel together and vibrate

• electric and magnetic waves π out of phase with each other, one reaching their peak the same time another reaches their trough, so in step

• electric and magnetic waves move perpendicular to each other and to the direction they’re travelling

what does a EM wave consist of?

an electric and magnet wave moving together and vibrating

what is the phase difference between the electric and magnet wave in an EM wave ?

in step, so they have a phase difference of π

what does it mean to be in ‘step’ ?

for a wave to reach their peak the same time another reaches their trough

what direction do the electric and magnetic waves in an EM wave travel?

perpendicular to each other and perpendicular to the direction of travel

do EM waves vibrate ?

yep

what is a photon?

a ‘packet’ (short bursts) of EM energy

what kind of energy is a photon?

EM

how are EM waves emitted?

in short bursts, known as photons. emitted by a charged particle when it loses energy

what is a photon emitted by?

a charged particle when it loses energy

under what circumstances does a charged particle lose energy?

• when a fast moving electron is stopped, slows down, or changed direction

• when an electron in the shell of an atom moves to a different shell of lower energy

why does a charged particle lose energy when a fast moving electron is stopped, slows down, or changes direction?

LOOK UP

why does a charged particle lose energy when an electron in it’s shell moves to a different shell of lower energy?

when there’s a vacancy in an inner shell, an electron de-excites by releasing energy via gamma photon, since the inner shell is of lower energy

what is the equation for photon energy?

E = hf

E - photon energy

h - planck’s constant, 6.63 × 10^-34 J

f - frequency (of photon)

what is planck’s constant?

6.63 × 10^-34 J