A freshly prepared radioactive source of half-life 2h emits radiation of intensity which is 64 times the permissible safe level.

Al displaces Fe from FeSO4 and forms Al2(SO4)3 which is colourless. The lower end of the test tube becomes warm.

(a) point source EXPLANATION:  Only for a point source the intensity can be written as I = E/4πr², where E is the strength of the source. Hence  E ∝ 1/r².

Overall luminous efficiency =Total luminous flux / Power input =35x685/100 = 239.75 lumen/W

The correct answer is (c) 1/r

The correct answer is (4) Use I = I0 e-μx

The correct answer is (a) (c)  (a) the maximum intensity of radiation will be near the frequency 2v0 (c) the total energy emitted will increase by a factor of 16.

(a) the number of photons emitted by the source in unit time increases (b) the total energy of the photons emitted per unit time increases

(c) Cobalt-60 is useful as a gamma ray source because it can be produced in predictable quantity and high activity by bombarding cobalt with neutrons. This is commonly used in...

(c) As it is given that half life of given substance is 4 months. The amount of substance left after 4 months = 1/2  The amount of substance left after 8 months...

Because FeSO4 gets hydrolysed if its solution is stored for long.