1.3 - Photons

Question 1

give the wave speed equation

Answer 1

C = λ f

(m/s) = (m) x (Hz)

Question 2

what is the EM spectrum

Answer 2

continuous spectrum of all the EM waves

Question 3

name the main parts of the electromagnetic spectrum in order of decreasing wavelength

Answer 3

Radio = >0.1m -

Microwave = - 1mm -

IR = - 700nm -

Visible = - 400nm -

UV = - 1nm -

X - rays = <1nm

Y- rays = <1nm

Question 4

what is unclear across the electromagnetic spectrum

Answer 4

the borders between the different types

• wavelengths tend to overlap another making no fine different between neighboring types of EM waves

Question 5

Diagram of an electromagnetic wave

• describe this kind of wave (labeling parts)

Answer 5

made up of an electro-field and a magnetic-field

• theses are perpendicular to another in the direction they travel together
• they are in phase; peak and troth at the same points

Question 6

when are electromagnetic waves emitted

• how does this occur (2)

Answer 6

when a charged particle losses energy

• fast moving e- is stopped / slowed / directional change
• e- moves from a higher to lower energy level shell

-

Question 7

how are electromagnetic waves emitted

Answer 7

in short bursts from the source

• go out in all directions (bursts that go out in same direction = packets)

Question 8

what is a photon

Answer 8

a wave packet of an EM wave

Question 9

give the equation of photon energy

• give the name and value of planks constant

Answer 9

E = h f

(J) = (Js) x (Hz)

h = planks constant (6.63x10^-34 Js)

Question 10

what does a light beam consist of

Answer 10

photons of the same frequency

Question 11

equation used to calc the power of a beam

Answer 11

P = nhf

(W) = (no of photons) x ( 6.63x10^-34Js) x (Hz)