Q. Using a nuclear counter the count rate of emitted particles from a radioactive source is measured. At t = 0 it was 1600 counts per second and t = 8 seconds it was 100 counts per second. The count rate observed, as counts per second, at t = 6 seconds is close to :

Solution:

at t = 0, $A_0 = \frac{dN}{dt} = 1600 C/s$
at t = 8s, A = 100 C/s
$\frac{A}{A_0} = \frac{1}{16} $ in 8 sec
Therefor half life is $t_{1/2} = 2 \; \sec$
$\therefore$ Activity at t = 6 will be $1600 ( \frac{1}{2} )^3$
= 200 C/s
$\therefore$ correct answer is (3)

You must select option to get answer and solution

Questions from JEE Main 2019

Physics Most Viewed Questions

1. The potential to which a conductor is raised, depends on ........

KCET 2005 Electrostatic Potential And Capacitance

3. In a permanent magnet at room temperature

KCET 2019 Moving Charges And Magnetism

5. In the following circuit, what are P and Q?

KCET 2019 Semiconductor Electronics: Materials Devices And Simple Circuits

8. For a transistor amplifier, the voltage gain

KCET 2019 Semiconductor Electronics: Materials Devices And Simple Circuits

9. “Parsec” is the unit of

BHU 2007 Physical World, Units and Measurements

10. “Parsec” is the unit of

BHU 2007 Physical World, Units and Measurements