CBSE Class 12 · 2013 · Modern PhysicsVery Short Answer

Define the activity of a given radioactive substance. Write its S.I. unit.

Answer: $R = λ N$ ; S.I. unit becquerel (Bq) = 1 decay/s.

Solution

Activity is the rate of disintegration of a radioactive sample, i.e. the number of nuclei decaying per unit time:

R = - \frac{d N}{d t} = λ N .

Its S.I. unit is the becquerel (Bq);

1 Bq = 1

disintegration per second.

R = λ N, unit: becquerel (Bq)

CBSE Class 12 Board · 2013 · Subjective