Exam 17: Electric Potential

A parallel plate capacitor with an air dielectric is attached to a voltage source and charged.The voltage source is removed,and then the plates are separated to double their previous distance.What happens to the electric field between the plates when they are separated?

A charge q₁ is placed on the y-axis at y = 4.0 m and the resulting potential at the position (3.0 m , 4.0 m) is 3.0 V.The charge q₁ is removed and a charge q₂ is placed on the x-axis at x = 3.0 m and the resulting potential at the position (3.0 m , 4.0 m) is 4.0 V.If both charges are in place simultaneously,what is the potential at (3.0 m , 4.0 m) ?

The electric field between two charged plates is 7.2 kN/C.If the plates are separated by 3.0 mm,what is the potential difference between them?

Three 1.0 $\mu$ C charges are placed along the x-axis,one charge at x = -10 cm, another at the origin,and the last one at x = 10 cm.What is the total potential energy of this arrangement?

Which of the following statements is true:

A conducting sphere of radius 20 cm is charged so that the electric field reaches 3.0 $\times$ 10⁵ V/m at its surface.What is the potential at the surface of the sphere?

A 2.5-mC charge is on the y-axis at y = 3.0 m and a 6.3-mC charge is on the x-axis at x = 3.0 m.What is the direction of the potential at the origin?

A pair of parallel conducting plates have potentials of -17 V and 55 V,respectively.An electron is ejected from the plate at potential -17 V and travels to the plate at 55 V.What is the speed of the electron as it strikes the 55 V plate,assuming it left the -17 V plate from rest? The mass of the electron is 9.11 $\times$ 10^-31 kg.

If the plate area,plate separation,dielectric strength,and dielectric constant all are doubled for a parallel plate capacitor,what happens to the maximum voltage for this capacitor?

How much charge is on a conducting sphere of diameter 20 $\mu$ m if its surface potential is at 50 mV?

Which of the following unit equations is true?

If protons are accelerated from rest in a Van de Graff accelerator through a potential difference of 1.00 MV,what is their resulting speed?

If the potential difference across the plates of a capacitor is doubled,what happens to the energy stored?

What is the distance between a -2.00 $\mu$ C charge and a -3.00 $\mu$ C charge if their potential energy is 0.491 J?

The electric potential at a distance d from a point charge is V.At a distance d',the potential is 2V.What is the ratio of electric field at d' to that at d?

A parallel plate capacitor has a paper dielectric having dielectric strength 8.0 kV/mm and dielectric constant 3.0.The plate area is 3000 cm² and the plate separation is 0.50 mm.What is the capacitance?

Two large equipotent surfaces are flat and parallel and separated by a relatively small distance compared to their size.One surface is at 25 V and the other is at 33 V.The surfaces are 1.25 cm apart.What is the direction of the electric field midway between the surfaces?

A parallel plate air-dielectric capacitor with circular plates has a separation gap of 1.5 mm.If it is desired to store 12 mJ in this capacitor,what must the plate area be for a voltage of 1.5 kV?

A 2.00 nC charge is placed on the x-axis at x = -3.00 cm,another 2.00 nC charge is place on the x-axis at x = 3.00 cm,and a third 2.00 nC charge is placed on the y-axis at y = 3.00 cm.What is the potential at the origin?

An electron is projected horizontally with a speed of 5.0 $\times$ 10⁶ m exactly in the middle of two parallel plates at potentials of -40 V and 104 V,respectively.The plate separation distance is 3.0 cm.The plates are long enough that the proton,rather than passing completely between the plates,eventually strikes the plate sitting at 104 V potential.What is the speed of the proton when it strikes the plate? The mass of the electron is 9.11 $\times$ 10^-31 kg.