1.In 1909 Robert Millikan was the ?rst to ?nd the charge of an electron in his n
ID: 2067729 • Letter: 1
Question
1.In 1909 Robert Millikan was the ?rst to ?ndthe charge of an electron in his now-famous
oil drop experiment. In the experiment tiny
oil drops are sprayed into a uniform electric
?eld between a horizontal pair of oppositely
charged plates. The drops are observed with
a magnifying eyepiece, and the electric ?eld is
adjusted so that the upward force q E on some
negatively charged oil drops is just su?cient
to balance the downward force m g of gravity.
Millikan accurately measured the charges on
many oil drops and found the values to be
whole-number multiples of1.6 × 10^-19C —the charge of the electron. For this he won
the Nobel Prize.
If a drop of mass 1.95918 × 10^-14kg remains stationary in an electric ?eld of1 × 10^5N/C, what is the charge on this drop?
The acceleration due to gravity is 9.8 m/s^2.
Answer in units of C
2.How many extra electrons are on this particular oil drop (given the presently known chargeof the electron)?
Explanation / Answer
1) let the total charge be Q. so, QE = mg ==> Q = mg/E = 1.91 x 10^-8 C 2) total no. of extra electrons = Q/ charge of the electron = 1.19 x 10^ 11.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.