| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.86 |
| Score | 0% | 57% |
Which of the following is not a characteristic of direct current?
an example power source is a generator |
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cannot easily travel distances without power loss |
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used to power your cell phone |
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electrons flow in only one consistent direction |
Direct current flows in only one direction in a circuit, from the negative terminal of the voltage source to the positive. A common source of DC is a battery. In contrast to the constant one-way flow of direct current, alternating current changes direction many times each second. Electricity is delivered from power stations to customers as AC because it provides a more efficient way to transport electricity over long distances.
Which of the following statements about a capacitor is false?
you should always discharge any capacitors before working on an electronic circuit |
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a capacitor remains charged even after the input voltage is removed |
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to discharge a capacitor safely, use a high-wattage resistor comparable to the capacitance of the capacitor |
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it is safe to touch a capacitor with your hands as long as it is small |
The purpose of a capacitor is to retain electric charge and it will do so even after its input voltage is removed. After the input voltage is removed, the capacitor will slowly discharge but, depending on the size and characteristics of the capacitor, discharging could take from a few minutes to a few years. So, it's never safe to touch a capacitor with your hands and you should make sure to discharge any capacitors in a circuit before working on it using an appropriately high-wattage resistor or a capacitor discharge tool.
| 90V 25A | |
| 90V 250A | |
| 45V 125A | |
| 9V 250A |
Connecting the 10 batteries in series multiplies their voltage while keeping their current the same yielding a 90V 25A configuration. Connecting the 10 batteries in parallel multiplies their current while keeping their voltage the same yielding a 9V 250A configuration. Using a series-parallel connection, 5 batteries can be connected in series and 5 can be connected in parallel resulting in a 45V 125A configuration.
General current flow in a transistor is from __________ to __________.
base, collector |
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collector, base |
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collector, emitter |
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base, emitter |
The transistor is the foundation of modern electronic devices. It is made entirely from semiconductor material (making it a solid state device) and can serve many different functions in a circuit including acting as a switch, amplifier, or current regulator. A transistor works by allowing a small amount of current applied at the base to control general current flow from collector to emitter through the transistor.
| series-parallel | |
| series | |
| orthogonal | |
| parallel |
Connecting the 10 batteries in series multiplies their voltage while keeping their current the same yielding a 120V 20A configuration. Connecting the 10 batteries in parallel multiplies their current while keeping their voltage the same yieleding a 12V 200A configuration. Using a series-parallel connection, 5 batteries can be connected in series and 5 can be connected in parallel resulting in a 60V 100A configuration.