Nuclear - energy, uses, etc

Question 1

2 types of nuclear reactions

Answer 1

fusion
fission

Question 2

Define nuclear fission

Answer 2

The splitting up of heavy nuclei to lighter nuclei which also releases energy and 2 or 3 neutrons.

Question 3

Define nuclear fusion

Answer 3

When lighter nuclei join to form a heavy nuclei and in the process, energy is released.

Question 4

what is a chain reaction

Answer 4

When emitted neutrons of the first split go and split other nuclei

Question 5

Describe the energy changes in a chain reaction

Answer 5

Huge and rapid release of energy

Question 6

Why must the chain reaction’s nuclear material be at or above a certain ‘critical’ mass

Answer 6

Otherwise too many neutrons escape

Question 7

use of uncontrolled chain reaction

Answer 7

atom bombs

Question 8

Why are high temps and pressure required for nuclear fusion.

Answer 8

Nuclei are charged and repel each other. In order to overcome the repulsion and join, they have to travel at extremely high speeds

Question 9

How does nuclear fusion occur in the sun if temp is only 15 mil not 40 mil which is needed on earth

Answer 9

Huge gravitational pull keep hydrogen and helium hot and compressed enough to maintain fusion

Question 10

Adv of fusion reactors over fission

Answer 10

Fusion reactors produce more energy per kilogram of fuel

hydrogen fuel can be easily obtained: extracted from sea water

Main waste is helium which is not radioactive

Question 11

Factors that influence the use of a radio-isotope

Answer 11

type of radiation emitted

half-life

Question 12

Name the use of radioisotopes - there r 5

Answer 12

(a) household fire (smoke) alarms

(b) irradiating food to kill bacteria

(c) sterilisation of equipment

(d) measuring and controlling thicknesses of
materials

(e) diagnosis and treatment of cancer using
gamma ray

Question 13

How is a radioactive isotope used for smoke detectors

which nuclear emission

Answer 13

alpha particles

2 metal plates with voltage across them
between plates there is a weak source of alpha particles

They ionize the air which moves between the 2 plates, so a small current always flows

when smoke enters the chamber, the ions attach to the smoke particles and hence the current reduces which triggers an alarm.

Question 14

What is irradiation of food

which nuclear emission

Answer 14

gamma

Gamma rays penetrate deep into food and kill bacteria which allows food to last longer without rotting

Question 15

How are medical instruments sterilized

Answer 15

same way as irradiation of food

Question 16

How is thickness monitored

which emission

Answer 16

beta

A beta source sends a stream of constant beta emission

a detector is on the other side of the object

by checking the count rate of the source on the detector, the objects thickness is determined along with the consistency of the thickness through the entire object

Question 17

Why is beta chosen for thickness monitoring

Answer 17

alpa - can’t penetrate anything at all

gamma - can penetrate everything

Question 18

How is cancer treated

which emission

Answer 18

Gamma radiation

Sevreal beams can be pointed from different directions to concentrate their energy at one point to destroy a tunmour.

Question 19

Explain rutherford’s gold foil experiment

Answer 19

A thin gold foil was bombarded with alpha particles which are positively charged

most passed through
some repelled extremely strongly
some deflected

Question 20

What could rutherford conclude from the experiment

Answer 20

Atom is largely empty space.

The positive charge and mass of the atom is concentrated at its nucleus in the centre.

electrons orbit the nucleus

Question 21

which model did the gold foil experiment disporve

Answer 21

plum pudding model - atom might be a sphere of positive charge with electrons (negative charge) dotted inside.

Question 22

Safety measures while handling radioactive materials

Answer 22

wear lead-lined gloves

use tongs while handling materials

if working with gamma or beta: use lead-lined body suits.

Workers wear a photographic film that blackens over time as it is exposed to radiatino. Lets them know when to take a break

Question 23

General safety goals when working with radio active materials

Answer 23

Maintain distance

Minimise exposure time

Question 24

How can radioactive materials be transported and stored

Answer 24

In containers made out of lead, concrete, or steel.

containers need to be properly sealed.