p1: radiation

Question 1

what do we do to make elements emit light

Answer 1

electrons absorbing energy from photons
free electrons

Question 2

how does an electron become excited

Answer 2

photon comes in and an electron absorbs its energy causing it to jump up a energy level

Question 3

how does an electron become ionised

Answer 3

photon comes in and gives too much energy to the electron causing it to jump ut of the atom

Question 4

what happens after an electron has been excited

Answer 4

After a while, they come back down and release energy(photons)

Question 5

what happens if the photon doesn’t have enough energy

Answer 5

pass through atom

Question 6

what are the absorption spectra

Answer 6

black lines that show wavelengths(/frequency) absorbed

Question 7

what are the emission spectra

Answer 7

whole spectrum will be b lack except parts that frequency has been emitted

Question 8

whats the differences between the emission spectra and absorption spectra and why

Answer 8

Expect more line son emission spectra
- because all electrons when they absorb they start at the ground state and end up at a specific energy level

however in emission spectras electrons can take any route they want

Question 9

what happens when we heat a metal and what is it called

Answer 9

electrons can escape from the surface
thermionic emission

Question 10

explain how fluorescent tubes work

Answer 10

filament lamp is heated causing thermionic emissionn
it then collides with the mercury gas inside
this causes the mercury electrons to excite and deexcite
this releases a UV photon
This UV photon collides with the phosphors that is coating the lamp
it then excites then dexcites relating photons
which we see as white light

Question 11

what does the photoelectric effect prove

Answer 11

light actss as a particle

Question 12

whyats the equation for energy of photons

Answer 12

planks constant(h6.63.10^-34) x frequency(hz)

Question 13

what is the photoelectric effect

Answer 13

When you shine light at a metal
photons collide with electrons giving them some of its energy
the electrons use this energy to get to the surface of the metal
they then use the remaining energy to overcome the work function and leaves the metal surface

Question 14

what does voltage =

Answer 14

energy / charge

Question 15

what is stopping potential

Answer 15

current normally flows as photoelectrons pass through the gap
stopping potential reduces current to 0

Question 16

what does the wave theory suggest

Answer 16

suggests that the amplitude of waves should determine the light energy

Question 17

why is thee wave theory wrong

Answer 17

low-frequency light will not release photoelectrons regardless of its intensity

Question 18

what does the particle theory suggest

Answer 18

frequency of light determines its energy(a few photons of a high frequency of light can cause photelectric effect)

Question 19

how do we do electron diffraction

Answer 19

heat metal filament in order to emit electrons
electrons then hit a fluorescent screen
they then for a diffraction patern

Question 20

what is de brogles wavelength

Answer 20

wavelength = planks constant/mass x velocity
or
wavelength = plank constant/momentum

Question 21

how do we work out the kenetic energy of waves

Answer 21

momentum^2/2xmass