Physics Test 10...

A nucleus disintegrates into two nuclear parts which have their velocities in the ratio 2 : 1. The ratio of their nuclear sizes will be :

A certain radioactive substance has a half life of 5 years. Thus, for a nucleus in a sample of the element, the probability of decay in 10 years.

The activity of a radioactive element decreased to one third of the original activity I₀ in a period of nine years. After a further lapse of nine years its activity will be :-

There are three lumps of a given radioactive substance. Their activity is in the ratio 1 : 2 : 3 now. What will be the ratio of their activities at any further date?

The radioactivity of a certain material drops to 1/16 th of the initial value in 2 hr. The half life of this radio-nuclide is :

The momentum of photon of energy 3MeV in kg m/s, will be -

Monochromatic light of frequency 6 × 10¹⁴ Hz is produced by a laser. The power emitted is 42.6 mW. The number of photons emitted, on the average, by the source per second is -

In photoemission, if intensity of radiation falling over surface is very low, then

Initial number of nuclei of a radioactive substance is 8 × 10¹⁵ and half life is 20 days. Then number of nuclei decayed in 60 days will be -

If half life of a radioactive isotope X is 30 years. It decays to another element Y which is stable. The two elements X and Y were found to be in the ratio of 1 : 3 in a sample of a given rock. The age of the rock was estimated to be -