• Part A A parallel-plate capacitor is constructed from two 15 cm x 15 cm electrodes spaced 1.5 mm apart. The capacitor plates are charged to + 20 nC, then disconnected from the battery. How much energy is stored in the capacitor? Express your answer using two significant figures. U = Value Units Submit Reguest Answer • Part B Insulating handles are used to pull the capacitor plates apart until the spacing is 2.8 mm. Now how much energy is stored in the capacitor? Express your answer using two significant figures. ? Uz = Value Units Submit Request Answer • Part C Energy must be conserved. How do you account for the difference between A and B? O Work was done to pull the plates apart. O The electric field supplied addtional energy. O Kinetic energy of the charges was transformed into potential energy. O The battery supplied additional energy Submit Resuest Answer

Auniform electric field of magnitude 3.8×10 N/C points in the positive z direction. Find the change in electric potential energy of a 7.5-uC charge as it moves from the origin to the point (0, 6.0m) Express your answer using one significant figure. Templates Symbols undo rego teset keyboard shortcuts Help AU = Submit: Requeet Answer • Part B Find the change in electric potential energy of a 7.5-uC charge as it moves from the origin to the point (6.0 m, 0). Express your answer using two significant figures TEmplates ymbols undo redo teset keyboard shortcuts Help AU = Submit Requeet Answer • Part C Find the change in electric potential energy of a 7.5-uC charge as it moves from the origin to the point (6.0 m, 6.0 m). Express your answer using two significant figures. Tempratesymbor undo rego Teset keyboard shortcuts help AU = J Submit RequeetAnswer

• Part A Electrostatic cleaners remove small dust particles and pollen grains from air by first lonizing them, then towing the air between the plates of a paralel plate capacitor, paralel to the plates, where electric forces deposit charged particies on one of the electrodes. A typical polien grain has a mass of 5.0 x 10". the lonizer charges it with 650 extra electrons, and a fan moves the air at 4.5 m/s Ignore air resistance and gravity. How long does it take a pollen grain to pass behween 12 cm x 12 cm electrodes? Express your answer with the appropriate units. At Value Units Submit Previous Anawers Request Answer Part B What menmum electric feid strength is needed to deflect the grain by 3.0 mm before t leaves the eiectrodes? Express your answer with the appropriate units. E. Value Units

a € Za 2a (b) (Q) (+Q) FQ Calculate the electric force on a charge, q near two charges, +Q and -Q, as shown in (a) and (b). Also note any place(s) that you could place q and the force would be zero. Leave your answer in terms of q, Q, a, and k or 47€0. •q

ACTIVITY #3 (Potential) • An object with a charge of -0.5 coulombs is pushed 0.2 meters toward a negatively charged plate with a force of 10 newtons. a. What is the energy required to do this? b. What is the potential difference between the object and the plate after it is pushed?

An electric field of strength E = 9500 N/C is directed along the +x-axis as shown. • C E • A • B What is the magnitude of the potential difference between point B and point A if the distance between these two points is 8 cm? V Submit Answer Tries 0/2 An electron is initially at rest at point B. How much kinetic energy (in electron-Volts, or eV) will the electron gain by moving to the higher potential at point A? eV Submit Answer Tries 0/2 What is the kinetic energy of the electron at point A measured in Joules?

• A • B Choose true or false for each statement below about the uniform electric field shown above. Point C is at a higher potential than point A 8The kinetic energy of a negative charge moved from point A to point C will decrease. 0The electrostatic force on a charge is greater at point B than at point A 0The potential energy of a positive charge moved from point B to point A will increase. The plate on the right is positively charged

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A 3.5-cm-diameter parallel-plate capacitor has a 1.5 mm spacing. The electric field strength inside the capacitor is 1.1x10° V/m. You may want to review (Pages 699 - 702) Part A What is the potential difference across the capacitor? Express your answer to two significant figures and include the appropriate units. AVc = Value Units Submit Request Answer • Part B How much charge is on each plate? Express your answer to two significant figures and include the appropriate units. HA Q = Value Units Submit Request Answer