# Chapter 1:Introduction¶

## Example 1.1, Page 12¶

In :
#initiation of variable
Mn=1.008665;Mp=1.007276                                     #Given mass of an electron and a proton in terms of u

#calculation
Md= Mn-Mp;                                                  #mass difference
Md2=Md*931.50;                                              #converting u into Mev/c^2 by multiplying by 931.5 MeV/c^2

#result
print "Mass difference in terms of U is",round(Md,4);
print"which equals in Mev/c^2. :",round(Md2,3);

Mass difference in terms of U is 0.0014
which equals in Mev/c^2. : 1.294


## Example 1.2, Page 12¶

In :
#initiation of variable
Mp=1.007276 ; Me=5.4858*10**-4; #mass of proton and electron in terms of U

#calculation
Mt=Mp+Me;                      #Total mass= sum of above masses

#result
print"The combined mass of an electron and a proton was found out to be in U.",round(Mt,3);

The combined mass of an electron and a proton was found out to be in U. 1.008


## Example 1.3, Page 13¶

In :
#initiation of variable
h=6.621*10**-34 ; c=2.9979*10**8;                  # h is in J/s and c is  in m/s
hc=h*c*((10**9)/(1.6022*10**-19));               #1e=1.602*10^-19 J and 1 m=10^9 nm

#result
print "The value of hc in  eV.nm is",round(hc,4);
print 'Hence zero at the end is significant.';

The value of hc in  eV.nm is 1238.8651
Hence zero at the end is significant.