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(b)
particles. Two positively charged or negatively charged particles will repel each other and will put as much distance between them as possible. On the contrary, a negatively charged particle and a positively charged particle will be irresistibly attracted to each other and will move nearer to it if they can. A subatomic particle can have zero charge (neutral) or 1 unit, either positive or negative, or in certain instances 2 units of charge, but nothing in between. No particle can have 1.25,1.5 or 1.7 units of charge. In other words, electric charge is also quantized like energy, and all the charge quanta are of the same size. A particle with mass and charge emerges as a particle personality. Spin : The third characteristic of “a subatomic particle is its "spin". A particle spins about a theoretical axis at exactly the same rate, neither slower nor faster. The spin of a particle is related to, but not identical to, our everyday concept of a spin of a top because it does not have any well-defined axis. Like every phenomenon in quantum mechanics, spin is also discontinuous i.e., quantized like energy and charge." Satish K. Gupta, op.cit., p.4 "Quantization of charge In earlier times, it was thought that the charge on a body can be increased in continuous manner. However, experiments show that charge on a body is always some integral multiple of a smallest unit of charge, which in magnitude is equal to the charge on an electron or a proton. The electron has a negative charge equal to 1.6 x 16-19 coulomb and charge on a proton is found to be exactly equal and opposite to that on electron i.e. equal to + 1.6 × 10-19 coulomb. If we regard 1.6 x 10-19 coulomb as e, then an electron has charge -e and a proton has charge + e. Any charged body will possess a total charge -e, -2 e, -3 e ....., if negatively charged and + e + 2e, + 3e, ......, if positively charged. In other words, a charged body (or a particle) cannot possess charge, which is a fraction of 1 e. This experimental fact is called the quantization of charge or discrete nature of charge. The fact that the charge on a body or a particle is always some integral multiple of a smallest unit of charge (+ 1.6 x 10-19 coulomb i.e. charge on a proton or an electron) is known as quantization of charge.
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