4.2. The Nuclear Model of the Atom http://www.ck12.org
FIGURE 4.7
The deflection of a cathode ray by a
magnet. From the direction and extent
of the deflection, Thomson was able to
determine the charge-to-mass ratio of the
electron.FIGURE 4.8
Millikan’s oil drop experiment: Oil drops
that are sprayed into the main chamber
fall through a tiny hole into an electric
field, after which they can be viewed
through a microscope. This experiment
allowed Millikan to determine the charge
of the electron.When tiny drops of oil were sprayed into a chamber, the oil drops picked up a static charge and were suspended
between two charged plates. Millikan was able to observe the motion of the oil drops with a microscope and found
that the drops lined up in a specific way between the plates, based on the number of electric charges that they had
acquired. From the data gathered in this experiment, he was able to accurately determine the charge of an individual
electron. Then, using Thomson’s previous measurement of an electron’s charge-to-mass ratio, he was also able to
calculate the mass of a single electron.
Charge of one electron=− 1. 602 × 10 −^19 C
Mass of one electron= 9. 11 × 10 −^28 g