Practice Problems for Exam 1
Coulomb force.
Calculate the electric force between an alpha particle (charge of 3.2x10-19 C) and an
aluminum nucleus (charge =20.8x10-19 C) located at a distance of 1.2x10-10m.
Electric field.
Determine the electric field at the origin due to the two charges A and B. Consider the
positions given in meters and charge of A=1.1C and B=-1.5C.
Electric potential.
A 35C charge is placed 0.65m from an identical 35C charge. Calculate the electric
potential at the point midway between them.
Capacitance, dielectrics:
Calculate the capacitance of the two plates shown in the figure when they are completely
submerged in a liquid whose dielectric constant, K is 3.4. Area of the plates=0.24 m 2,
distance between the plates = 0.36 mm.
[Dielectric permittivity of vacuum,  o  8.85 x10 12 F / m ]
Capacitance, Dielectrics and Storage of Electric Energy.
A cardiac defibrillator is used to shock a heart that is beating erratically. A capacitor in
this device is charged to 2.5 kV and stores 950 J of energy. What is the capacitance?