1. Physics 2005…in 2009

2. Auguste Coulomb
Coulomb’s Torsional Balance

3. How did mankind begin to find out about the atom?
BIG SURPRISE FOR RUTHERFORD: MOST PARTICLES WENT STRAIGHT THROUGH THE GOLD FOIL.
Explaination:
“much of the atomic volume was now assumed to contain only the very light electrons, which could not produce much deflection. Accordingly, many alpha particles would pass through the atom, deflected only slightly by the electrons and the long-range Coulomb interaction with the nucleus”

4. How did mankind measure charge?
Milliken
first let oil drops fall until they reached terminal velocity.
Measured the terminal velocity.
at terminal velocity the oil drop is not accelerating.
So the total force acting on it must be zero, gravity+drag=0 ,
This lets us calculate the mass of each oil drop
Finally, use an electric field to stop the falling –then the force of
Gravity is exactly cancelled by the electric force, which determines
The charge. x
Electric force
Oil
Gravity

5. Milliken’s actual drawing, he measured e=1
Milliken’s actual drawing, he measured e=1.5924(17) x 10^−19 coulombs which is a touch low, due to an error in the viscosity of air