phys II homework 18 and 19

Charge is always conserved.

true

How many charges exist in nature?

2

The electric field is a scalar quantity.

false

Like charges ___ each other.

repel

By what factor would the Coulomb force decrease if you increased the distance between two charges by a factor of 5?

25

Compare the electrostatic force between an electron and proton separated by a certain distance with the gravitational force between them.

2.27 × 10³⁹

How many coulombs of positive charge are there in 4.00 kg of plutonium, given its atomic mass is 244 and that each plutonium atom has 94 protons?

1.48 × 10⁸ C

What is the repulsive force between two pith balls that are 8.00 cm apart and have equal charges of – 30.0 nC?

1.27 × 10^-3 N

Common transparent tape becomes charged when pulled from a dispenser. If one piece is placed above another, the repulsive force can be great enough to support the top piece’s weight. Assuming equal point charges (only an approximation), calculate the magnitude of the charge if electrostatic force is great enough to support the weight of a 10.0 mg piece of tape held 1.00 cm above another.

1.04 nC

What is the direction and magnitude of an electric field that supports the weight of a free electron near the surface of Earth?

5.58 × 10^-11 N/C

What is a capacitor?

Capacitors are devices that store electrical charge.

The unit eV is used to describe what physical quantity?

Energy

Grounding a conductor removes excess charge from the conductor.

true

List three different references we've discussed in class where V=0.

all of the above

What is a polar molecule?

A molecule with a separation of charge.

How might we change the capacitance?

All of the above.

The electric potential is a vector quantity.

false

Capacitance does not depend on voltage.

true

We have a 8pF and 10pF capacitor in parallel, what is the total capacitance?

18pF

We have a 8pF and 10pF capacitor in series, what is the total capacitance?

4.44pF