1. Flow of Charge: The Current 2. Electric Resistance and Ohm's Law 3. Voltage Law and Current Law 4. Chapter Quiz

In order for a charge to flow, it needs a push (a force) and it is supplied by voltage, or potential difference. The charge flows from high potential energy to low potential energy.

V_{A} - V_{B} = 12 - 2 = 10 V.

If there is a potential difference between two regions and if we join them together, the charge will flow. The charge will always move until the force acting on it is reduced to a minimum or until the voltage becomes the same.

1 C/s = 1 A

A German scientist Georg Simon Ohm experimented with circuits and found out the relationships between current, voltage, and resistance. It became known as Ohm's law and can be written in an equation V=IR, where V is voltage, I is current, and R is resistance.

Answer: You first have to modify the equation V = IR to I = V / R. Then you just have to input the numbers into this equation. I = 3 / 0.5 = 6 A [ampere].

a). What is the voltage if current is 0.5 A [ampere] and resistance is 0.8 ohm?

(e.g. "0.1") V V=I*R

b). What is the resistance if voltage is 3.0 V and current is 1.5 A?

(e.g. "1") A R=V/I

R = k * (L / A)

where:

A potentiometer uses this characteristic. It can change its resistance by controlling its length. This apparature is used in T.V. volume, light controller, and everything else dealing with changing its electricity gradually.

Symbol for potentiometer is

and its inside looks like this .

The gray bar inside is connected to the black wire of its around, and it rotates (see above). Let's say an electrical line is connected to the left and the middle. If the gray bar is at the left, then the circuit will have small resistance because the length of the black wire outside is shorter. When the gray bar trun to the right, then it will have larger resistance.

For example, imagine a circuit with a battery and a bulb. If the battery generates 3 V, then the bulb must consume 3 V, because the sum of decrease in voltage (-3 V consumed by the bulb) must be equal to the sum of increase in voltage (+3 V generated by the battery).

A junction is any point where wires are splits into two or more.

In the left diagram, incoming current (2 A) is being split into half at a junction point (1 A), and then is combined back to the original current (2 A).

In other words, current coming in is equal to the current going out.

What is the current on X, Y, and Z? (resistance on X, Y, and Z are same)

(e.g. "10") A

Try Chapter 13 Quiz and see how much you learned.

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