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CHAPTER11_
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içi—“
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'SPONTANEOUS DISINTEGRATÏON
Introduction.—In
1896, Becquerel discovered that .…
uranirmiSalts emitted radiations, capable of blackening
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graphic plate even after passing through bodies which were opaque
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to light
It has been found, since then, that all of the heavier
'
elements from Z =‘84 to 92, at the end of the Periodic Table,
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spontaneouslÿ emit radiations which are capable not only of
eningfä‘i‘photographic plate but also of ioni2ing a gas through which
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'
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ot
…
ï
’
.?
'
_
F1G.…r11—1. 'Magnetic deection of alpha, beta
and gamma rays;
:,
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_
;
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making it_a conductor of electricity, and of
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_or’sn’tiall ashésof…light When they strike» a
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_m3tÇlrial—. Th6actionoftheradiations‘make it possible not only to
but also __to méa’Sur'ethe amount of radioaCt—iÿé
«.
..
btnthd V…th'0ughÿ'ohlÿ small quantity is seatteædz?
*
!
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11—2TheNatureof
:
,
areem1ttedby radioafetiÿe«substances
three
may
240
,
‘
"