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QAIPMT-2011-Ph-1912: NEET 2011 Physics - Class 12 AIPMT-2011-Ph-1912 Solution: Electrons used in an electron microscope are accelerated by a…
Electrons used in an electron microscope are accelerated by a voltage of 25 kV. If the voltage is increased to 100 kV then the de-Broglie wavelength associated with the electrons would increase by 2 times decrease by 2 times decrease by 4 times increase by 4 times
Multiple Choice Options
- A 150 years
- B 200 years
- C 250 years
- D 100 years
Step-by-Step Verified Solution
Initial number of atoms of X is N 0
and Initial number of atoms of Y is 0
Number of atoms after time t, for X is N and for Y is N 0 - N
According to the question,
N N 0 _ N = 1 15
_ N N 0 = 1 16
As N N 0 = ( 1 2 ) n where n is the no. of half lives
_ ( 1 2 ) n = 1 16
_ n = 4
t = nT 1/2
= 4 _ 50 = 200 years
Hence, the age of rock is 200 years.