Tutorial 2

RADIATION SCIENCE Tutorial 2 1.

The uranium nuclide 4.7 x 103 years. Find

23896

A ) Decay constant ( λ )

u

has an activity 30 μCi with half life

T12

=

T12

=

0.693λ

4.7 x 103 = 0.693λ λ

0.693λ

= 4.7 x 103

= 1.474 x 10-4 years-1

B ) Activity at 3.0 x 103 years, 7.0 x 103 years, 1.2 x 104 and 1.5 x 104 years ( i ) N = No e-λt 3.0 x 103 years

1.9278 x 10-5 Ci

( ii ) 7.0 x 103 years

1.059 x 10-5 Ci

( iii ) 12.0 x 103 years

0.5116 x 10-5 Ci

( iv ) 15.0 x 103 years

0.3288 x 10-5 Ci

C ) Complete the following table Time 3.0 x 103 years 7.0 x 103 years 12.0 x 103 years 15.0 x 103 years

Activity 1.9278 x 10-5 Ci 1.059 x 10-5 Ci 0.5116 x 10-5 Ci 0.3288 x 10-5 Ci

Percentag e 41 % 23 % 11 % 7%

D ) Draw the graph the log graph and normal graph

2. Explain how the x-ray are produce from the x-ray tube When an electron passed near or bombared a charged nucleus target as an electron

passes closer to a positive ( +ve ) charge nucleus contained in the targed material, it is deflected from its path because of it electrical attraction to the nucleus and hence experience an acceleration of electromagnetic radiation. This radiation must appear in the form of photon carries energy, the electron must lose kinetic energy because of its encounter with the targed nucleus.

Scatted electron Incident photon Target

θ

Scatted Photons

Figure above shows that when high speed electron is accelerated trough a thousand volt of potential difference bombared on a metal targed such as tungsten, so x-ray are produced.

3. Calculate the x-ray wave length and frequency if the potential difference is 120 kV e∆v = hfmax ( 1.602 x 10-19) ( 120000 ) = hfmax fmax = ( 1.602 x 10-19 ) ( 120000 ) h = 2.9 x 1019 λ

=

ef

=

e2.9 x 1019

= 1.034 x 10-4 4.

Calculate the energy of x-ray are produce from tungsten material at Ekα line an Ekβ line Tungsten

18474

W

( i ) E ( kα) = ( z - 1 ) x 13.6 eV = ( 74 - 1 ) x 13.6 eV = 992.8 eV ( ii ) E ( kβ) = ( 74 - 9 ) x 13.6 eV = 884.0 eV