Author : Khairi

RADIOACTIVITY

Radioactivity is the spontaneous decay of an unstable nucleus to be a stable nucleus by emitting radioactive rays or energetic particles

Author : Khairi

Radioactive rays consist of :

Alpha (α)

Beta (β)

Gamma (γ)

SYMBOL OF ELEMENT

4He

2

0e

-1

CHARGE

negative

Mass

positive

Nocharge

big

small

Nomass

RADIOACTIVITY

None

Author : Khairi

PENETRATING POWER

Thin paperAluminium(a few mm) Lead

(a few cm)

α

βγ

RADIOACTIVITY

Author : Khairi

EFFECT OF ELECTRIC FIELD

-ve +ve

γ

β

α

β-particle is deflected with larger deflection because it has a smaller masscompared to a-particle

γ-particle is unaffectedbecause it has no charge

β-particle is deflected to positive plate because it is negatively charged

α-particle is deflected to negative plate because it is positively charged

RADIOACTIVITY

Author : Khairi

RADIOACTIVITY

X X X X X XX

X X X X X XX

X X X X X XX

X X X X XX

X X X X X XX

X

EFFECT OF MAGNETIC FIELD

X = magnetic field into the paper

γ

β

α

γ-particle is unaffectedbecause it has no charge

β-particle is deflected with larger deflection

because it has a smaller mass compared to

α-particle

α-particle is deflected with small deflection because it has a large mass

Author : Khairi

RADIOACTIVE DECAY

RADIOACTIVITY

A process where an unstable nucleus

reducing its mass to be a stable nucleus by

emitting radioactive rays or energetic particles

Author : Khairi

NUCLEAR EQUATION

238

92U

234

90Th + X

Nuclear equation above shows that uranium-238 decayed toThorium-234 and emits X-ray.

What is the X-ray ?

Nucleon number

238 = 234 + y

y = 4

y

Proton number

92 = 90 + z

z = 2

z

RADIOACTIVITY

Author : Khairi

NUCLEAR EQUATION

238

92U

234

90Th + X

Nuclear equation above shows that uranium-238 decayed toThorium-234 and emits X-ray.

What is the X-ray ?

Nucleon number

238 = 234 + y

y = 4

4

Proton number

92 = 90 + z

z = 2

2

RADIOACTIVITY

Particle X is

4

2He= α

ALPHA DECAY

Author : Khairi

EXERCISE

24

11Na

24

12Mg + X

Nuclear equation above shows Natrium-24 decays tomagnesium-24 and emits an X-ray

What is the X-ray ?

Nucleon number

24 = 24 + y

y = 0

0

= β

RADIOACTIVITY

Author : Khairi

EXERCISE

24

11Na

24

12Mg + X

Nuclear equation above shows Natrium-24 decays tomagnesium-24 and emits an X-ray

What is the X-ray ?

Nucleon number

24 = 24 + y

y = 0

0

Proton number

11 = 12 + z

z = -1

-1

Particle X is

0

-1e = β

RADIOACTIVITY

BETA DECAY

Author : Khairi

60

27Co

60

27Co + X

Nuclear equation above shows cobalt-60 decays and emit an X-ray ?

What is the X-ray ?

Nucleon number

60 = 60 + y

y = 0

0

= γ

RADIOACTIVITY

EXERCISE

Author : Khairi

60

27Co

60

27Co + X

Nuclear equation above shows cobalt-60 decays and emit an X-ray ?

What is the X-ray ?

Nucleon number

60 = 60 + y

y = 0

0

Proton number

27 = 27 + z

z = 0

0

Particle X is

0

0= γ

RADIOACTIVITY

GAMMA DECAY

EXERCISE

Author : Khairi

226

88Ra Rn + α

Nuclear equation above shows Radium-226 decays toRadon and emits α-ray

What is nucleon number and proton number of Radon ?

α4

2He

y = 222 z = 86

RADIOACTIVITY

EXERCISE

Author : Khairi

226

88Ra Rn +

Nucleon number

226 = y + 4

y = 222 z = 86

4

2He

RADIOACTIVITY

What is nucleon number and proton number of Radon ?

Nuclear equation above shows Radium-226 decays toRadon and emits α-ray

EXERCISE

Author : Khairi

226

88Ra Rn +

Nucleon number

226 = y + 4

y = 222

Proton number

88 = z + 2

z = 86

4

2He

RADIOACTIVITY

What is nucleon number and proton number of Radon ?

Nuclear equation above shows Radium-226 decays toRadon and emits α-ray

EXERCISE

Author : Khairi

Nuclear equation above shows Uranium decays toThorium and emits α-ray

What is the nucleon number and proton number of uranium ?

Nucleon number

A = 234 + 4

= 238 = 92

U234

90Th + α

RADIOACTIVITY

EXERCISE

Author : Khairi

Nuclear equation above shows Uranium decays toThorium and emits α-ray

What is the nucleon number and proton number of uranium ?

Nucleon number

A = 234 + 4

= 238

Proton number

Z = 90 + 2

= 92

U234

90Th + α

RADIOACTIVITY

EXERCISE

Author : Khairi

DECAY SERIES

238

92U

234

90Th

234

91Pa

234

92U

α β β

RADIOACTIVITY

Author : Khairi

DECAY SERIES GRAPH

238

92U

234

90Th

234

91Pa

234

92Uα β β

Nucleon number,A

Proton number,Z

238

234

90 91 92

U

Th Pa U

α

β β

RADIOACTIVITY

Author : Khairi

The contents in the bag at airport can be examined by

A. X-ray

B. Gamma ray

C. Ultraviolet ray

D. Infrared ray

Gamma ray has high penetration power

PAST YEARS QUESTIONPAST YEARS QUESTION

Author : Khairi

Which of the following shows the type of ray S and T ?

Ray S

A. α

B. α

C. β

D. γ

Ray T

β

γ

γβ

α β γ

PAST YEARS QUESTIONPAST YEARS QUESTION

Author : Khairi

Which of the following statements is a characteristic of gamma radiation ?

A. It has a positive charge

B. It is an electromagnetic wave

C. It has a higher ionizing power than alpha

D. It has a lower penetrating power than beta radiation

Gamma ray is neutral and a type of electromagnetic wave

PAST YEARS QUESTIONPAST YEARS QUESTION

Author : Khairi

What is the number of the alpha particles and beta particles emitted during this process ?

α particles

A. 2

B. 3

C. 4

D. 1

β particles

3

2

1

1

αβ βαα

PAST YEARS QUESTIONPAST YEARS QUESTION

Author : Khairi

Which of the following has a similar characteristic to β-particle ?

A. proton

B. Electron

C. Helium nucleus

D. Electromagnetic wave

PAST YEARS QUESTIONPAST YEARS QUESTION

Author : Khairi

What is the value of X and Y ?

A. 0

B. 1

C. 1

D. 2

X

1

1

2

2

YNucleon number

238 = 230 + 0 + 4YY = 2

Proton number

92 = 90 – X + 2Y92 = 90 – X + 4

X = 2

PAST YEARS QUESTIONPAST YEARS QUESTION

Author : Khairi

What is X ?

A. β particle

B. α particle

C. Energy

D. γ particle

Nucleon number

235 + 1 = 141 + 92 + 3 + XX = 0

Proton number

92 = 56 + 36 + XX = 0

PAST YEARS QUESTIONPAST YEARS QUESTION

Author : Khairi

a. Name both rays emitted by the radioisotope.Beta and gamma

b. Explain why the rays follow the path.

Beta is negatively charged and gamma is neutral

PAST YEARS QUESTIONPAST YEARS QUESTION

Author : Khairi

PAST YEARS QUESTIONPAST YEARS QUESTION

What is meant by radioactivity ?

The spontaneous decay of unstable nuclei by emitting radioactive ray

Author : Khairi

PAST YEARS QUESTIONPAST YEARS QUESTION

State the charges of radioactive emission.

Positive

Author : Khairi

PAST YEARS QUESTIONPAST YEARS QUESTION

Compare the voltage of EHT and deflection of the radioactive emission.

EHT in diagram 10.2 is higher than in diagram 10.1.

Deflection of emission in diagram 10.2 is bigger than in diagram 10.1.

Author : Khairi

PAST YEARS QUESTIONPAST YEARS QUESTION

State the relationship between the EHT and the strength of electric field between two plates.

EHT is directly proportional to the strength of electric field between two plates

Author : Khairi

PAST YEARS QUESTIONPAST YEARS QUESTION

State the relationship between the strength of electric field between two plates and the deflection of emission.

The deflection is directly proportional to the strength of electric field between two plates