3.8 Millikan's Oil Drop Experiment

Select all that apply. What was the main purpose of Millikan's oil drop experiment?

• to determine the magnitude of the acceleration due to gravity

• to determine the ideal voltage that batteries should contain

• to determine the charge of an electron

• to determine the mass of a proton

Millikan determined that

• the acceleration due to gravity is 9.8 m/s²

• the charge of an electron is -1.60 * 10^-19 C

• the universal gravitational constant is 6.67 * 10^-11 m³/kgs²

• everything is relative

In Millikan's experiment, he examined these forces acting on oil drops:

• gravity and normal

• normal and friction

• electric and normal

• gravity and electric

In order to equate the two forces, the oil drop had to be

• stationary

• moving upward

• moving downward

• moving diagonally

The oil drop's movement was altered by

• jedi mind powers

• holding/poking the oil drop with a toothpick

• changing gravity

• changing the voltage across the charged plates

If the charge on an oil drop was -2.72 * 10^-18 C, how many electrons were absorbed by the oil drop?

• 2

• 5

• 13

• 17

If an oil drop absorbed 4 electrons, what would its total charge be?

• 6.4 * 10^-19 C

• -6.4 * 10^-19 C

• 8.9 * 10^-18 C

• -8.9 * 10^-18 C

When comparing the charges of electrons and protons, we can say that

• their charges are equal in magnitude and sign

• their charge magnitudes and signs are different

• their charges are equal in magnitude but opposite in sign

• their charge magnitudes are different but their signs are the same

In a Millikan-type experiment, two horizontal plates are 3.6 cm apart. A small spherical mass of 2.7 * 10^-15 kg remains stationary when the potential difference between the plates is 850 V. If the upper plate is positive, calculate the charge on the sphere.

• 1.1 * 10^-18 C

• 2.5 * 10^-18 C

• 1.0 * 10¹⁷ C

• 3.0 * 10^-18 C