physics p4

Question 1

what is half life?

Answer 1

time taken for half of the radioactive nuclei in a sample to decay

Question 2

what is the activity?

Answer 2

the overall rate of decay of all of the radioactive isotopes in a sample

Question 3

what is the activity measured in?

Answer 3

becquerels (Bq)

Question 4

what is used to measure the radioactive decays per second?

Answer 4

geiger counter

Question 5

what is a geiger counter?

Answer 5

used to measure the the radioactive decays (radiation emitted) per second

Question 6

which electrons have the lowest energy in the atom

Answer 6

at the smallest distance from the nucleus

Question 7

what is in the photon model

Answer 7

electromagnetic radiation is emitted and absorbed as energy (photons)

Question 8

what is an alpha particle?

Answer 8

2 protons and 2 neutrons

(a nucleus of a helium atom)

Question 9

what is a beta particle?

Answer 9

an electron

Question 10

what is a gamma ray?

Answer 10

it is an electromagnetic wave so it doesn’t have a mass or charge

Question 11

what happens in a beta decay?

Answer 11

a neutron decays to a proton and an electron
the electron is emitted as a beta particle

Question 12

what number and symbols are used in an alpha nuclear equation?

Answer 12

4
He
2

Question 13

what number and symbols are used in an beta nuclear equation?

Answer 13

0
e
-1

Question 14

what happens in gamma decay?

Answer 14

gamma ray does not cause a change in mass or charge

Question 15

what happens in neutron emission?

Answer 15

nuclei decays and produces large amounts of neutrons which then emit

Question 16

what symbol and numbers are used in an neutron emission nuclear equation?

Answer 16

1
n
0

Question 17

what is contamination?

Answer 17

when you take radioactive material inside your body or if it is on your skin. it cannot be removed once inside body

Question 18

what is irritation?

Answer 18

when radioactive material is outside body but radiation can travel into the body

Question 19

what can ionising radiation do?

Answer 19

can damage dna inside cells which causes cancer

Question 20

what do unstable nuclei emit?

Answer 20

radiation:
alpha, beta, gamma, neutron

Question 21

how do you detect radiation?

Answer 21

geiger-müller tube / geiger counter

Question 22

how does the geiger counter detect radiation?

Answer 22

device clicks when radiation enters it. each click is a tiny current that produces when radiation ionises atoms inside tube

Question 23

what are waves?

Answer 23

an oscillation that transfers energy

Question 24

what are electromagnetic waves used for?

Answer 24

used to communicate between two phones

Question 25

what type of wave is a sound wave?

Answer 25

longitudinal

Question 26

what are transverse waves?

Answer 26

direction of the oscillations are perpendicular to the direction of the wave

Question 27

what are longitudinal waves?

Answer 27

direction of oscillations are parallel to direction of the wave

Question 28

how do you model waves?

Answer 28

using ripple on water waves to model transverse waves

Question 29

how do you measure the velocity of waves?

Answer 29

a ripple tank

Question 30

how do you use a ripple tank?

Answer 30

- motor vibrates bar, causing waves on surface of water - image of waves are on screen underneath waves as light passes through it

Question 31

how do you measure the velocity of sound?

Answer 31

- time how long it takes to hear an echo of a clap at a certain distance from the wall - use an oscilloscope

Question 32

what are the waves of the electromagnetic spectrum in order?

Answer 32

radio waves micro waves infrared visible light ultraviolet x-ray gamma ray

Question 33

what do electromagnetic waves travel through?

Answer 33

a vacuum at 3.0 x 10^8 m/s