bab 8 radioactivity

Question 1

History of Radioactivity

Answer 1

1) 1895, Wilhelm Roentgen discovered x-ray.
2) 1896, Henri Becquerel discovered radioactivity.
3) 1897, Marie & Pierre Currie detected radioactivity through its ionising effects.
4) Marie Currie died at the age of 67 from a disease caused by prolonged gamma ray exposure

Question 2

Radioactive elements

Answer 2

Radioactive elements
Uranium-238
Thorium-234
Cobalt-60

Product of decay
Thorium-234 + Helium nucleus (a)
Protactinium-234 + Electron (3)
Cobalt-60+ gamma ray (y)

Question 3

Units of Radioactivity

Answer 3

curie (Ci)
- 1 Ci3.7 x 1010 decays/s
becquerel (Bq)
- 1 Bq = 1 decay/s

Question 4

Positive lon (Cation)

Answer 4

• an atom that loses electrons

Question 5

Negative lon (Anion)

Answer 5

• an atom that gains electrons

Question 6

Jonising Radiation

Answer 6

• radiation that produces +ve and -ve ions while passing through air

Question 7

Non-ionising Radiation

Answer 7

• radiation that doesn’t produces ions while passing through the air
  dution

Question 8

Types of lonising Radiation

Answer 8

check notes for dis

Question 9

Sources of ionising radiation in the environment

Answer 9

Natural
- Cosmic rays
- Background radiation

Man-made
- Nuclear accidents
- Nuclear tests

Question 10

Structure of the sun

Answer 10

check notes

Question 11

Phenomena that Occur on the Surface of the Sun

Answer 11

• Granules, Sunspot and Solar Cycle
• Prominence
• Solar Flares
• Coronal Mass Ejections
• Solar wind

Question 12

Granules, Sunspot and Solar Cycle

Answer 12

• photosphere are made of granules (grainy structure)
• sunspot are the dark regions seen on the sun
  
  • dark because temperature are lower than the surroundings
  • can last for more than a week
  • always exist in pairs or groups
• sun cycle is the activity of the sunspots seems to appear and disappear according to a cycle that last 11 years

Question 13

Prominence

Answer 13

• huge loop of glowing gases over the sunspot
• can reach heights of hundreds of thousands of kms
• can last for several days or months
• can throw out matter from the Sun, speed=600-1000km s¹

Question 14

Solar Flares

Answer 14

• column of large amounts of charged gases erupting from the Sun
• attain max. brightness within a few seconds or minutes and become dim after a few minutes or hours
• light from solar flares takes 8 min to reach the Earth
• charged gas particles take 10 min to reach the Earth
• collide with atoms & molecules on atmosphere & create aurora

Question 15

Coronal Mass Ejections

Answer 15

• huge cloud of plasma that erupts from Sun together w/ solar flares
• ejection of magnetic gas particles and appears like expanding cloud
  take 3 days to reach the Earth
• collide with atoms & molecules on atmosphere & create aurora

Question 16

Solar Wind

Answer 16

particles (electron, proton, beta) that erupt from the Sun to outer space

Question 17

Definition of Earth’s Magnetosphere

Answer 17

• region in outer space surrounding the Earth where the Earth’s magnetic field combine with outer magnetic field

Question 18

Formation of Earth’s Magnetosphere

Answer 18

• formed by interaction between the magnetic field brought by the solar wind and Earth’s magnetic field

Question 19

Importance of Earth’s Magnetosphere

Answer 19

• function as a biological shield to protect the Earth from solar wind

Question 20

Space Weather
phenomena that occur on the surface of the Sun

Answer 20

• solar flares
• prominence
• sunspot
• coronal mass ejection

Question 21

Space Weather
phenomena that occur in the space

Answer 21

• solar wind
• solar radiation storm
• geomagnetic storm