In 1909, Robert Millikan was the first to find the charge of an ele...
In 1909, Robert Millikan was the first to find the charge of an electron in his now-famous oil-drop experiment. In that experiment, tiny oil drops were sprayed into a uniform electric field between a horizontal pair of oppositely charged plates. The drops were observed with a magnifying eyepiece, and the electric field was adjusted so that the upward force on some negatively charged oil drops was just sufficient to balance the downward force of gravity. That is, when suspended, upward force \( q E \) just equaled \( m g \). Millikan accurately measured the charges on many oil drops and found the values to be whole number multiples of \( 1.6 \times 10^{-19} \mathrm{C} \) - the charge of the electron. For this, he won the Nobel prize. If a drop of mass \( 1.08 \times 10^{-14} \mathrm{~kg} \) remains stationary in an electric field of \( 1.68 \times 10^{5} \mathrm{NC}^{-1} \), then the charge of this drop is (1) \( 6.40 \times 10^{-19} \mathrm{C} \) (2) \( 3.2 \times 10^{-19} \mathrm{C} \) (3) \( 1.6 \times 10^{-19} \mathrm{C} \) (4) \( 4.8 \times 10^{-12} \mathrm{C} \) 📲PW App Link - https://bit.ly/YTAI_PWAP 🌐PW Website - https://www.pw.live
