Exam 18: Direct-Current Circuits Sources of EMF: Part A

A parallel-plate capacitor has a capacitance of 20 µF.What potential difference across the plates is required to store 22 × 10−⁵ C on this capacitor?

When charges q_a,q_b,and q_c are placed respectively at the corners a,b,and c of a right triangle,the potential at the midpoint of the hypotenuse is 20 V.When the charge q_a is removed,the potential at the midpoint becomes 15 V.When,instead,the charge q_b is removed (q_a and q_c both in place),the potential at the midpoint becomes 13 V.What is the potential at the midpoint if only the charge q_c is removed from the array of charges?

Suppose two equipotential surfaces are the planes x = 3 m and x = 5 m.If the potential at the x = 3 m surface is 10 V and the potential at the x = 5 m surface is 50 V,what is the magnitude of the electric field between the two surfaces?

A capacitor is made by taking two sheets of aluminum foil,each 0.022 mm thick and placing between them 2 sheets of paper which comes from a ream of 500 sheets,the ream being 5.5 cm thick,with sheets measuring 216 mm by 279 mm (the usual 8 By 11).What is the capacitance of the capacitor made this way if the dielectric constant of the paper is 3.7? (ε₀ = 8.85 × 10 ^-12 C²/N × m²)

A pair of parallel plates,forming a capacitor,are charged.The plates are pulled apart to triple the original separation,the charges on the plates remaining the same.What is the ratio of the final energy stored to the original energy stored?

Electrons in an x-ray machine are accelerated from rest through a potential difference of 80,000 V.What is the kinetic energy of each of these electrons in eV?

The dielectric strength of rutile is 6.0 × 10⁶ V/m,which corresponds to the maximum electric field that the dielectric can sustain before breakdown.What is the maximum charge that a 10−¹⁰-F capacitor with a 0.50-mm thickness of Rutile can hold?

Two charges,each of charge q,are separated by a distance d.The distance between the charges is doubled.If the original potential energy of the arrangement was 40 mJ,by how much does the potential energy change when the charges are moved to the increased distance?

At what distance from a point charge of 14 μC would the electrical potential be 4.2 × 10⁴ V? (k_e = 8.99 × 10⁹ N⋅m²/C²)

A parallel-plate capacitor is attached to a fixed voltage supply.If the plates are then separated to double the initial value,what happens to the energy stored by the capacitor?

If three 3.0-µF capacitors are connected in parallel,what is the combined capacitance?

Two protons,each of charge 1.60 × 10−¹⁹ C,are 3.00 × 10−⁵ m apart.What is the change in potential energy if they are brought 1.00 × 10−⁵ m closer together? (k_e = 8.99 × 10⁹ N·m²/C²)

Suppose two charges,one positive and one negative,are separated by a distance d.Where can two equipotential surfaces at different potentials intersect in the region near the charges?

A 9.0-V battery moves 200 mC of charge through a circuit running from its positive terminal to its negative terminal.How much energy was delivered to the circuit?

An electron in a cathode ray tube is accelerated through a potential difference of 10 kV.What kinetic energy does the electron gain in the process? (e = 1.6 × 10−¹⁹ C)

Two capacitors with capacitances of 1.5 μF and 0.25 μF,respectively,are connected in parallel.The system is connected to a 100-V battery.What electrical potential energy is stored in the 1.5-μF capacitor?

Equipotential surfaces around a point charge are

A 6.0-μF capacitor is attached to a 20-V power supply.How much energy is stored in the capacitor?

If the electric field is halved in a region of space,what happens to the electric field energy in a 10 cm³ volume of this space.

Find the electrical potential at 0.055 m from a point charge of 6.0 μC.(k_e = 8.99 × 10⁹ N⋅m²/C²)