numericals
1
calculate De-broglie wavelength of electron moving at a speed of 1℅ of light given m=9.1×10^-31kg, h=6.63×10^-34kgm^-2s^-1.
sol.
 mass of the electron = 9.1× 10^-31kg
 Planck's constant = 6.63×10^-34kgm^2s^-1
velocity of electron = 1℅ speed of light
                                  = 1/100 × 3×10^8m/s=3×10^6
applying all value in relation
     √= h/m×v
 √= (6.63×10^-34) /  (9.1×10^-31 × 3×10^6) 
√=2.43×10^-10metre   ans
2
An electron moving with K. E of 2.275×10^-10J
calculate its De-broglie wavelength. 
 sol.
 mass of the electron = 9.1× 10^-31kg
 Planck's constant = 6.63×10^-34kgm^2s^-1
K. E energy of electron= 2.275×10^-25J
we know K. E= 1/2 m×V^2
  so applying all value in relation
we get
 2.275 ×10^-25 = 1/2 m×V^2
  2.275×10^-25=1/2×9.1×10^-31×V^2
  V^2=0.5×10^6m^2/s^2
   V=.707×10^3m/s   ans
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