photons and electrons

Question 1

threshold /cut off frequency

Answer 1

minimum frequency of incident radiation at which electrons will be emitted from a particular metal

Question 2

work function

Answer 2

the minimum amount of energy needed to emit an electron from the surface of a metal
is material specific

Question 3

photo electric effect

Answer 3

process that occurs when
light shines on a metal and electrons are ejected

establishes the
quantum theory and it illustrates the particle nature of light

Question 4

photo electrons

Answer 4

electrons ejected from a metal by incident ligh

Question 5

light

Answer 5

Electromagnetic wave set up by changing interacting electric and magnetic fields ( that propagate through space)
interacts w/ atoms in metallic surfaces (where there is a sea of delocalised electrons)
different to other waves- does not diminish as it does not require a medium
carries photons

Question 6

generating action of light

Answer 6

charged particle accelerates + produces changing electric + magnetic field (mutual induction)

Question 7

wavelength

Answer 7

distance it travels to complete 1 form/cycle

Question 8

frequency

Answer 8

number of cycles/wave forms per second

Question 9

infrared + below

Answer 9

on the left
radio,microwave
long wavelength
low frequency therefore low energy
non ionisinh
electromagnetic

Question 10

ultraviolet + above

Answer 10

right
x-ray, gmaa ray
damaging
short wavelength
high frequency therefore high energy
ionising - radioactivity (“ripping” off electrins)

Question 11

ultraviolet + above

Answer 11

right
x-ray, gmaa ray
damaging
short wavelength
high frequency therefore high energy
ionising - radioactivity (“ripping” off electrins)

Question 12

photon’s liberating electrons

Answer 12

1 photon w/ sufficient energy can liberate 1 electron

Question 13

if energy of photon less than work function

Answer 13

frequency less than threshold frequency therefore no photoelectric effect

Question 14

if Eph = Wo

Answer 14

frequency = fo
therefore photo electric effect occurs, e- released

Question 15

Eph greater than Wo

Answer 15

f greater than fo
photo electric effect occurs , e- released
extra enetgy - Ek (kinetic)

Question 16

source of atomic emission spectra

Answer 16

Gas discharge tubes energise atoms of an element allowing electrons within each atom to move to higher energy levels. Electrons at high energy levels will fall back down to lower energy levels releasing energy in the form of photons of light. Small atoms with a few electrons and energy levels produce relatively simple emission spectra. Larger atoms with many electrons and energy levels produce very busy emission picture