### Concept Items

#### 19.1 Ohm's law

- The electrons flow from the negative terminal of the battery to the positive terminal of the battery.
- The electrons flow from the positive terminal of the battery to the negative terminal of the battery.

- Current is directly proportional to the resistance.
- Current is inversely proportional to the resistance.
- Current is proportional to the square of the resistance.
- Current is inversely proportional to the square of the resistance.

- Resistance is the property of materials to resist the passage of voltage.
- Resistance is the property of materials to resist the passage of electric current.
- Resistance is the property of materials to increase the passage of voltage.
- Resistance is the property of materials to increase the passage of electric current.

- V = I^2R
- V = \frac{R}{I}
- V = \frac{I}{R}
- V = IR

#### 19.2 Series Circuits

In which circuit are all the resistors connected in series?

What is the voltage and current through the capacitor in the circuit below a long time after the switch is closed?

- 0 V, 0 A
- 0 V, 10 A
- 10 V, 0 A
- 10 V, 10 A

#### 19.3 Parallel Circuits

- No, because for a parallel combination of resistors, the resistance through the remaining circuit increases.
- Yes, because for a parallel combination of resistors, the resistance through the remaining circuit increases.

- Adding resistors in parallel gives the current a shorter path through which it can flow, hence decreasing the overall resistance.
- Adding resistors in parallel gives the current another path through which it can flow, hence decreasing the overall resistance.
- Adding resistors in parallel reduce the number of paths through which the current can flow, hence decreasing the overall resistance.
- Adding resistors in parallel gives the current a longer path through which it can flow, hence decreasing the overall resistance.

#### 19.4 Electric Power

To draw the most power from a battery, should you connect a small or a large resistance across its terminals? Explain.

- Small resistance, because smaller resistance will lead to the largest power
- Large resistance, because smaller resistance will lead to the largest power

If you double the current through a resistor, by what factor does the power dissipated by the resistor change?

- Power increases by a factor of two.
- Power increases by a factor of four.
- Power increases by a factor of eight.
- Power increases by a factor of 16.