Track quiz
Every rule from this chapter is below, word for word. Use it to check your answers.
| Idea | Rule |
|---|---|
| Charge on the move | Current is charge passing one point each second. The charge that leaves a cell comes back. A lamp spends energy, not charge. In a one-loop circuit, a break stops the current everywhere. |
| Measuring a circuit | An ammeter sits in the path and reads the flow. A voltmeter reaches across a part and reads the push. Each meter tells the truth only in its own place. |
| Ohm's law | This is Ohm's law. At a fixed temperature, current is proportional to the push. R stays the same, so V and I climb together. |
| Resistance depends on | A longer wire has more resistance. A thicker wire has less resistance. The material and temperature decide the rest. |
| Series and parallel | Series has one path, so resistances add. The current is the same at every point. Parallel gives each resistor its own path, so the total resistance falls. A break in series stops everything. In parallel, only that branch goes dark. |
| Heating effect | A current heats a wire as it flows. Heat equals current squared times resistance times time. Keep resistance and time the same. Double the current and the heat is four times as much. |
| Power | Power is voltage times current, in watts. It also equals current squared times resistance. And it equals voltage squared divided by resistance. A longer running time changes the energy, not the power. |
| The meter | The meter counts energy: power times time. One unit is the energy a thousand watts deliver in one hour. The bill grows with the watts and with the hours. |
A cell drives 2 A through a lamp for 5 s. How much charge passes?
An ammeter is joined across a lamp instead of in the path. What happens?
A wire carries 0.5 A at 2.5 V. The push is tripled to 7.5 V. What is the current now?
Wire P is twice as long as wire Q. Both share the same material and area. Compare their resistance.
A 2 Ω and a 3 Ω resistor are in series. The cell is 10 V. Find the current.
A 3 Ω and a 6 Ω resistor are in parallel. What is the total resistance?
A 4 Ω resistor carries 2 A for 5 s. How much heat does it make?
A bulb is marked 6 V, 12 W. Treat its resistance as fixed. It runs on 3 V. What power does it use?
A 1500 W heater runs for 4 hours. How many units does it use?
Chapter 11, Electricity, is done. Your next track is Magnetic Effects of Electric Current.