The counting rate observed from a radioactive source at t = 0 second was 1600 counts per second and at t = 8 seconds it was 100 counts per second. The counting rate observed, as counts per second at t = 6 seconds will be
(a) 400
(b) 300
(c) 200
(d) 150
Correct option (c) 200
Explanation:
After 8 sec., the counting rate falls to
100/1600 = 11/16 = (1/2)4 th part;
Time ** = 8/4 sec. = 2 sec.
Therefore after 6 seconds, the counting rate should be
(1/2)3 in the part of 1600, i.e . 1/8 x 1600 = 200
