The smallest unit of charge is − 1.6 × 10 − 19 C, which is the charge in coulombs of a single electron. Robert Millikan was able to measure the charge on small droplets of oil by suspending them between a pair of electrically charged plates. Which of the values are possible charges of those oil droplets? − 8.0 × 10 − 19 C − 3.2 × 10 − 19 C − 1.2 × 10 − 19 C − 5.6 × 10 − 19 C − 4.8 × 10 − 19 C − 9.4 × 10 − 19 C

Explanation:

Charge of an Electron

Since Robert Millikan determined the charge of a single electron is

Every possible charged particle must have a charge that is an exact multiple of that elemental charge. For example, if a particle has 5 electrons in excess, thus its charge is

Let's test the possible charges listed in the question:

. We have just found it's a possible charge of a particle

. Since 3.2 is an exact multiple of 1.6, this is also a possible charge of the oil droplets

this is not a possible charge for an oil droplet since it's smaller than the charge of the electron, the smallest unit of charge

cannot be a possible charge for an oil droplet because they are not exact multiples of 1.6

Finally, the charge is four times the charge of the electron, so it is a possible value for the charge of an oil droplet

Summarizing, the following are the possible values for the charge of an oil droplet:

magnified images possible images can be real = projected onto a screen

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it