NEET Questions Solved

NEET - 2008

A particle of mass 1 mg has the same wavelength as an electron moving with a velocity of 3×106 ms-1. The velocity of the particle is 

(a) 2.7×10-18 ms-1

(b) 9×10-2 ms-1

(c) 3×10-31 ms-1

(d) 2.7×10-21 ms-1

(mass of electrons =9.1×10-31kg)

Q54:

Wavelength of a particle is given by 

                  λ=hp

where h is Planck's constant and wavelength of an electron is given by 

                         λe=hpe

but                 λ=λe

so,               p=pe

or                mv=mevem

or           v=mevem

putting the under given data 

me=9.1×10-31 kg , ve=3×106 m/s;m=1 mg =1 ×10-6 kg v=9.1×10-31×3×1061×10-6=2.7×10-18  ms-1

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