Itis now believed that protons and neutrons (which constitute nuclei ofordinary matter) are themselves built out of more elementary unitscalled quarks. A proton and a neutron consist of three quarks each.Two types of quarks, the so called ‘up’ quark (denoted byu) of charge (+2/3) e,and the ‘down’ quark (denoted by d) of charge (−1/3)e,together with electrons build up ordinary matter. (Quarks of othertypes have also been found which give rise to different unusualvarieties of matter.) Suggest a possible quark composition of aproton and neutron.
Itis now believed that protons and neutrons (which constitute nuclei ofordinary matter) are themselves built out of more elementary unitscalled quarks. A proton and a neutron consist of three quarks each.Two types of quarks, the so called ‘up’ quark (denoted byu) of charge (+2/3) e,and the ‘down’ quark (denoted by d) of charge (−1/3)e,together with electrons build up ordinary matter. (Quarks of othertypes have also been found which give rise to different unusualvarieties of matter.) Suggest a possible quark composition of aproton and neutron.
A proton has threequarks. Let there be n up quarks in a proton, each having acharge of 
.
Charge due to n upquarks
Number of down quarksin a proton = 3 − n
Each down quark has acharge of 
.
Charge due to (3 −n) down quarks 
Total charge on aproton = + e
Number of up quarks ina proton, n = 2
Number of down quarksin a proton = 3 − n = 3 − 2 = 1
Therefore, a proton canbe represented as ‘uud’.
A neutron also hasthree quarks. Let there be n up quarks in a neutron, eachhaving a charge of 
.
Charge on a neutron dueto n up quarks 
Number of down quarksis 3 − n,each having a charge of 
.
Charge on a neutron dueto 
downquarks = 
Total charge on aneutron = 0
Number of up quarks ina neutron, n = 1
Number of down quarksin a neutron = 3 − n = 2
Therefore, a neutroncan be represented as ‘udd’.
A proton has threequarks. Let there be n up quarks in a proton, each having acharge of .
Charge due to n upquarks
Number of down quarksin a proton = 3 − n
Each down quark has acharge of .
Charge due to (3 −n) down quarks
Total charge on aproton = + e
Number of up quarks ina proton, n = 2
Number of down quarksin a proton = 3 − n = 3 − 2 = 1
Therefore, a proton canbe represented as ‘uud’.
A neutron also hasthree quarks. Let there be n up quarks in a neutron, eachhaving a charge of .
Charge on a neutron dueto n up quarks
Number of down quarksis 3 − n,each having a charge of .
Charge on a neutron dueto downquarks =
Total charge on aneutron = 0
Number of up quarks ina neutron, n = 1
Number of down quarksin a neutron = 3 − n = 2
Therefore, a neutroncan be represented as ‘udd’.
