1.3 Photons Flashcards
What is light a part of
The spectrum of electromagnetic waves
What is the speed of light
3.00 * 10^8 ms^-1
What form of radiation do all objects emit
Infrared
In what circumstance do all electromagnetic waves at the same speed (speed of light)
In a vacuum
What is the wavelength of electromagnetic radiation given by
λ = c/f
What units are often used to express light wavelengths
Nanometres nm
Where 1nm = 10^-9m
An electromagnetic wave consists of an electric wave and a magnetic wave which travel together and vibrate…
…perpendicular to each other and to the direction in which they are travelling
In phase with each other. They reach a peak together so they are in phase
Electromagnetic waves are emitted by a charged particle when it…
…loses energy
Electromagnetic waves are emitted by a charged particle when it loses energy. This can happen when:
A fast-moving electron is stopped (for example in an X-ray tube) or slows down or changes direction
An electron in a shell of an atom moves to a different shell of lower energy
Electromagnetic waves are emitted as ______ ______ of ______ , each leaving the source in a different ______. Each ______ is a packet of electromagnetic waves and is referred to as a ______.
Short Bursts Waves Direction Burst Photon
Who developed the photon theory
Einstein in 1905
What is the photoelectric effect
The emission of electrons from a metal surface when light is directed at the surface
What did Einstein imagine photons to be like
Flying needles
Photon energy equation
E = hf
Where E is the photon energy
h is the Planck constant (6.63*10^-34 Js)
Photons in a laser beam are of the same…
…frequency
