Question

. For a ‘n’ particle system how many pairs of particles are required to calculate the total potential

energy of system of n particle ?
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Answer 1

For a system of n particles, nC2 pairs of particles are required to calculate the total potential energy of the system.

• For eg :
• Lets consider system of 4 particles.

Here the number of pairs of particles for energy is,

• q1q2, q1q3, q1q4 , q2q3, q2q4, q3q4 = 6
• We know 6 = 4C2 .

For any number of particles, the number of ways of choosing any 2 particles a a time without considering the order is nC2.