Questions:

1) What is the electric field strength between two parallel plates separated by 3.2 mm if a potential difference of 30 volts is applied across them?

2) An electron beam experiences a force of 6.5×10^-15 N when it is fired at a perpendicular magnetic field with a strength of 10T. Calculate the velocity of the electrons:

3) Two parallel plates are separated by a distance of 4 mm. The electric field strength between the plates is 100V. It is determined that the mass of an oil drop which is suspended between the plates is 2×10⁻⁶ g. How many excess electrons are on the oil drop?