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2000 WAEC Physics Theory (a)(1) State the energy transformations which take place during the operation of a modern x-ray...

Physics
WAEC 2000

(a)(1) State the energy transformations which take place during the operation of a modern x-ray tube.
(ii) Distinguish between hard and soft x-rays.

(iii) State three uses of x-rays.

(iv) Mention one hazard of over-exposure to x-rays in a radiological laboratory, and indicate any two safety precautions.

(b) A possible fusion reaction is \(^2_1 H + ^2_1 H \to ^3_1H + ^1_1H + Q\)

where Q is the energy released as a result of the reaction. If Q = 4.03 MeV, calculate the atomic mass of \(^3_1H\) in atomic mass units. (\(^2_1 H = 2.01410 U; ^1_1H = 1.00783 U; 1U = 931 MeV\))

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Explanation

(i) Electrical \(to\) thermal \(to\) mechanical (kinetic energy) \(to\) thermal \(to\) electromagnetic

(ii) Distinction between hard and soft X-rays

Hard X-rays Soft x-rays

(i) High (target) voltage

(ii) short wavelength

(iii) High penetration

(iv) produced by high voltage

Low (target) voltage

Long wavelength

Low penetration

Produced by low voltage

(iii) Uses:

- Used to detect hidden cracks in materials

- Used to detect alteration to work of art

- To show broken bones in human body

- used in crystallography i.e. to study crystals

- used in diagnosis of ulcer

(iv) Hazards: genetic mutations

- skin burn

- leukemia

- Tissue damage

- Tissue damage

- baldness

- graying

- cataracts

(v) Safety precautions:

use of dosimeter, badges of GM counters

- wearing of lead coats

- Periodic medical counters

- wearing of lead coats

- periodic medical check up

 

(b)

\(^2_1H + ^2_1H \to ^3_1H + ^1_1H + Q\)

Let atomic mass unit of tritium \(^3_1H\) be X

2.01410 x 2 x 931 = (x + 1.00783) 931 + 4.03

\(\frac{3750.254 - 4.03}{931}\) = x + 1.00783

4.0238 - 1.0078 = x

3.106 = x

 


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