MCQ
If the decay or disintegration constant of a radioactive substance is $\lambda ,$ then its half life and mean life are respectively
  • A
    $\frac{1}{\lambda}$ and $\frac{\log _e 2}{\lambda}$
  • $\frac{\log _e 2}{\lambda}$ and $\frac{1}{\lambda}$
  • C
    $\lambda \log _e 2$ and $\frac{1}{\lambda}$
  • D
    $\frac{\lambda}{\log _e 2}$ and $\frac{1}{\lambda}$

Answer

Correct option: B.
$\frac{\log _e 2}{\lambda}$ and $\frac{1}{\lambda}$
$\frac{\log _e 2}{\lambda}$ and $\frac{1}{\lambda}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

A particle moves in a region having a uniform magnetic field and a parallel, uniform electric field. At some instant, the velocity of the particle is perpendicular to the field direction. The path of the particle will be:
The half life of the isotope $11^{\mathrm{Na}^{24}}$ is $15$ hrs. How much time does it take for $\frac{7}{8}^{th}$  of a sample of this isotope to decay
Two bulbs of $500$ watt and $200$ watt are manufactured to operate on $220$ volt line. The ratio of heat produced in $500 \ce{W}$ and $200 \ce{W},$ in two cases, when firstly they are joined in parallel and secondly in series, will be
There are two conductors X and Y carrying a current I and moving in the same direction. p and q are two electron beams also moving in the same direction. Will there be attraction or repulsion between the 2 conductors and between the two electron beams separately?
In the figure given below, the current passing through $6 \Omega$  resistor is
What happens to the force between magnetic poles when their pole strength and the distance between them are both doubled(a) Force increases to two times the previous value(b) No change(c) Force decreases to half the previous value(d) Force increases to four times the previous value
 
 
 
 
Two parallel, long wires carry currents $i_1$ and $i_2$ with $i_1 > i_2$. When the currents are in the same direction, the magnetic field at a point midway between the wires is $10 \mu\text{T}.$ If the direction of $i_2$ is reversed, the field becomes $30 \mu\text{T}.$ The ratio $\frac{\text{i}_1}{\text{i}_2}$ is :
In the circuit shown, the point $‘B\ ’$ is earthed. The potential at the point $‘A\ ’$ is
Two wires of same size whose resistivities$\rho_1$ are $\rho_2$ and are joined in series. The equivalent resistivity of the combination will be:
A cell of internal resistance r is connected to an external resistance R. The current will be maximum in R, if(a) R = r(b) R < r (c) R > r (d) R = r/2