A count rate meter shows a count of 240 per minute from a given radioactive source. One hour later the meter shows a count rate of 30 per minute. The half-life of the source is
|
(a) 120 min |
(b) 80 min |
(c) 30 min |
(d) 20 min |
(d) 20 min
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Two charges +3.2 
and -3.2
kept 2.4 Å apart forms a dipole. If it is kept in uniform electric field of intensity 4 
then what will be its electrical energy in equilibrium
|
(a) + 3 |
(b) -3 |
(c) -6 |
(d) -2 |
A convex lens is made of a material having refractive index 1.2. Both the surfaces of the lens are convex. If it is dipped into water $(\mu=1.33),$ it will behave like:
The current i in an induction coil varies with time t according to the graph shown
in figure. Which of the following graphs shows the induced emf (e) in the coil with time
|
(a)
|
(b)
|
(c) |
(d)
|
