Bodies P, Q, R, S are labelled as having charges Q_P = 0.5 10⁻¹⁹C , Q_Q = 0.7 10⁻¹⁹C , Q_R = 2.1 10⁻¹⁹C , Q_S = 4.8 10⁻¹⁹C respectively. Select the body having the correct charge. [Given electronic charge = e = 1.6 10⁻¹⁹C ]

Step-by-step solution

According to the principle of quantization of charge, the charge on a body must be an integral multiple of the elementary charge e = 1.6 10⁻¹⁹ C . Q = ne For body P, n = 0.5 10⁻¹⁹ 1.6 10⁻¹⁹ = 5 16 (not an integer) For body Q, n = 0.7 10⁻¹⁹ 1.6 10⁻¹⁹ = 7 16 (not an integer) For body R, n = 2.1 10⁻¹⁹ 1.6 10⁻¹⁹ = 21 16 (not an integer) For body S, n = 4.8 10⁻¹⁹ 1.6 10⁻¹⁹ = 3 (an integer) Since n is an integer only for body S, the charge Q_S = 4.8 10⁻¹⁹ C is possible. Answer: Q_S = 4.8 10⁻¹⁹C