Q25 of 30 Page 201

Define ‘half -life’ and ‘average-life’ of a radioactive substance. What is the relation between the two?

Half-life is a constant of character. It measures the time needed of a given amount of that substance to reduce by half by emission of radiation.


So,


It is average time taken by any radioactive element nucleus to undergo decay.


So,


More from this chapter

All 30 →
23

Obtain an expression for focal length of a combination of thin lenses in contact.

 24

Three immiscible liquids of densities d1 > d2 > d3 and refractive indices μ1 > μ2 > μ3 are put in a beaker. The height of each liquid column is . A dot is made at the bottom of the beaker. For near normal vision, find the apparent depth of the dot.

 26

Using a suitable combination from a NOR, an OR and a NOT gate, draw circuits to obtain the truth tables given below:

(i)



(ii)



 27

Define the terms ‘modulation index’ for an AM wave. What would be the modulation index for an AM wave for which the maximum amplitude is ‘a’ and the minimum amplitude is ‘b’?