Saved Static Electricity + Electric Circuits

Typically, protons cannot be gained or lost from an atom because they are

More massive than electrons and tightly bound inside the nucleus

are positively charged particles.

Only protons

Two balloons are shown below. One is neutral, and the other is negative. Balloon X
will ___balloon Y.

attract because a neutral will never repel but will instead become polarized and attract.

Two balloons, X and Y, are placed near each other and subsequently attract each other.
If balloon X is positively charged, then Y MUST NOT be _.

positive

Balloons X, Y, and Z are suspended from strings as shown below. Negatively charged
balloon X attracts balloon Y and attracts balloon Z. Balloon Y ___.

may be positive and may be neutral

A rubber balloon is rubbed on a wool sweater. In the process, electrons are transferred
from the sweater to the balloon. As a result, the sweater acquires

a lot of mass

The best explanation for how a positively charged object can become grounded is that
the object

Gains electrons from another object

A positively charged metal sphere is touched by a person standing on the ground. The
metal sphere subsequently becomes neutral. This is because

Electrons pass from the person (ground) to the sphere

Two metal conducting pop cans are touching each other. A positively charged balloon
is brought near the can on the left. The cans are separated while the balloon is nearby.
After the balloon is removed, the cans are brought back together. When touching again,
the can on the right is

Neutral

Two neutral pop cans are touching each other. A negative balloon is brought near the
can on the left. The cans are separated while the balloon is nearby. After the balloon is
removed, the balloon is

Negative

A positive balloon is brought near a neutral conducting sphere. While the balloon is
near, the sphere is touched (grounded). At this point, there is a movement of electrons

Out of the sphere into the ground

A negative balloon is brought near a neutral conducting sphere. While the balloon is
near, the sphere is touched (grounded). The ground is removed while the balloon is still
near. Afterwards, the sphere will be

Positive

A negative balloon is brought near a neutral conducting sphere. As it approaches,
electrons move

From the left side of the sphere to the right side

A positive balloon is brought near a conducting sphere. As it approaches, electrons move
a. Out of the sphere into the air

From the right side of the sphere to the left side

A charge Q creates an E-field. A test charge q is used to measure the strength of the E-
field at a distance d from Q. The force F is experienced by the test charge q. The E-field
strength at this location is given by the expression ___.

kq/d
2 and F/Q

Does a test charge matter? q vs Q

It's insignificant!

A charge Q creates an E-field. A test charge q is placed a distance d away in order to
measure the strength of the field at that location. A doubling of q would

Not alter the E-field strength

Series vs Parallel Circuits

If components are in series, the current remains the same through all elements.
If components are in parallel, the total current splits, meaning different branches may have different currents.

If the circuit in your IPOD were analogous to a water circuit at a water park, then the voltage would be comparable to ___.

The water pressure between the top and bottom of the circuit

Which of the following occurs when a rechargeable battery is recharged?

The battery, which has run out of chemical reactants, has its chemicals reformed.

The metric unit of work is the ___ and the metric unit of power is the ___.

joule, watt

A 12-Volt battery will ___.

Provide 1 C of charge with 12 J of energy

A battery does 24 J of work for every 4 C of charge that it encounters during a 3 s time period. What is the voltage of the battery?

8 V

If the resistance of a circuit is tripled, then the current through the circuit would be___.

1/3 as much

Which of the following will cause the current through a circuit to decrease?

Decrease the voltage
Increase the resistance

The resistance of a wire will decrease if it is ___.

Made shorter
Made thicker

A certain circuit contains a battery, wires, and a light bulb. Which of the following would cause the bulb to shine less brightly?

Decrease the voltage
Increase the resistance
Open the circuit

The unit that is used to express resistance is

ohms

Three identical bulbs are connected to a battery as shown below. Which of the following is NOT true?

The potential difference between X and Z is greater than that between Y and W.

A 12 V battery is connected to the 3 resistors below. The equivalent resistance is

15 ohms

The current in the battery in circuit X is ___ that in the battery in circuit Y.

½ (see picture)

Which adjustments could be made that would increase the current in the battery?

decrease the resistance of bulb X
decrease the resistance of bulb Z
increase the voltage of the batter

As more and more resistors are added in parallel in a circuit, the equivalent resistance ____ and the total current of the circuit ___.

Decreases
increases