1. At what distance would be repulsive forces between two protons have a magnitude of 0.25 nN? (10 point) 2. If a proton and an electron are released when they are 3.80 x 10-10m apart, a) find the initial force between the particles b) find the initial accelerations of each of the particles. (20 points) 3. A positive charge of 63.0 nC is placed in a uniform electric field that is directed vertically upward and that has a magnitude of 7.35 x 104 N/C. a) what force is exerted by the electric field on the charge? b) what work is done by this electric force when the charge moves 3.84 m at the angle 30 degrees downward from the horizontal? Draw a diagram of 3 vectors: electric field, force, and displacement (20 point) 4. Two large metal parallel plates carry opposite charges of equal magnitude. They are separated by 75.0 mm, and the potential difference between the plates is 265 V. What is a magnitude of the uniform electric field in the region between the plates? (5 point) 5. A point charge has a value 45 pC. At what distance from the point charge is electric potential equal to 55 V? (10 point)6. A parallel -plate air capacitor has a capacitance of 0.20 /F and a charge of magnitude 0.500 uC on each plate. What is a potential difference between the plates? (5 point) (see next page) 7. A 3.0OuF and 5.00uF capacitors are connected in parallel, and this combination is connected across 90.0 V potential difference. a) draw a diagram of this combination Find: b.) potential difference across each of capacitors c) the charge on each capacitor. (15 points)8. A parallel plate capacitor has capacitance Co = 12.0 pF when there is air between the plates. The separation between the plates is 0.10 mm. A dielectric with K=2.71 is inserted between the plates of the capacitor, completely filling the volume between the plates. The capacitor is connected with a battery. a) find the difference of potentials if the electric field between the plates is 2.50 x 103 V/m . b) find the capacitance of this capacitor with dielectric inside c) find the magnitude of charge on each plate (15 points)