nuclear radiation

Question 1

describe the nature of alpha

Answer 1

a helium nucleus
most ionising
most dangerous form of radiation

Question 2

describe the nature of beta

Answer 2

negatively charged
a very high speed electron that is ejected from the nucleus when a neutron changes into a proton
mildly ionising

Question 3

describe the nature of gamma

Answer 3

a very high energy light wave
very short wavelength
very high frequency
weakly ionising
member of the EM spectrum

Question 4

define activity

Answer 4

the number of nuclear disintegrations per second

Question 5

define half-life

Answer 5

the time it takes for the activity in a radioactive source to fall to half its original value.

Question 6

what units are used to measure activity

Answer 6

Bq - becquerels

Question 7

what units are used to measure half life

Answer 7

time eg: - seconds, years, days etc

Question 8

how would you measure half life in an experiment

Answer 8

First measure the background radiation (no source present) using the Geiger-Müller tube and counter

Place a radioactive source a set distance from the GM tube and measure the count rate at set time intervals for a suitable time period

Deduct the background count rate from the source count rate, to get the corrected count rate

Plot a graph of corrected count rate vs. time and read the half-life from the graph.

Question 9

what are the dangers of ionising radiation to living things

Answer 9

Cells can be altered by ionising radiation and change their function.
Cells can be destroyed by ionising radiations.
This can lead to the creation of cancer cells.

Question 10

formula to calculate activity

Answer 10

A = N/t (activity = number of nuclear disintegrations/time in SECONDS

Question 11

define absorbed dose

Answer 11

the energy absorbed per unit mass of the absorbing material

Question 12

formula to calculate Absorbed dose (D)

Answer 12

D=E/m (absorbed dose = energy in joules/mass in KG

Question 13

units for absorbed dose?

Answer 13

Gy ( grays ) or J/kg, J kg-1 ( joules per kilogram )

Question 14

ionising ability of gamma?

Answer 14

low

Question 15

ionising ability of beta?

Answer 15

moderate

Question 16

ionising ability of alpha?

Answer 16

high

Question 17

penetration of alpha?

Answer 17

low
stopped by paper

Question 18

penetration of beta?

Answer 18

moderate
stopped by aluminium

Question 19

penetration of gamma?

Answer 19

high
stopped by lead/few metres of concrete

Question 20

define equivalent dose?

Answer 20

a more accurate estimation of damage done by radiation than absorbed dose

Question 21

units for Equivalent dose

Answer 21

sv (sieverts)

Question 22

relationship for equivalent dose

Answer 22

H=DWr (equivalent dose=absorbed doseweighting factor)

Question 23

define equivalent dose rate

Answer 23

how rapidly the equivalent dose was absorbed.

Question 24

formula for equivalent dose rate

Answer 24

H(with a dot on top)=H/t (eq dose rate=eq dose/time)

Question 25

what is the radiation weighting factor

Answer 25

because diff radioisotopes do diff amounts of damage, we use a table to factor that into the equivalent dose.

Question 26

describe nuclear fusion process

Answer 26

when two light nuclei join/fuse together to form one single, larger nucleus. This process creates LOTS of energy

Question 27

describe nuclear fission process

Answer 27

the splitting of large, unstable nuclei into smaller nuclei, by hitting the large nucleus with a slow neutron causing it to split into ‘daughter nuclei’, and also releasing 2 or 3 more neutrons, which can be used to continue the process in a chain reaction.

Question 28

challenges of nuclear FUSION?

Answer 28

-can’t be done on earth, needs high VERY temps and pressures