| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.44 |
| Score | 0% | 69% |
Which of the following will increase the magnetic field produced by the electric current in a wire?
wind the wire into a coil |
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construct the wire from conductive material |
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construct the wire from insulative material |
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wrap the wire around a ceramic core |
A moving electric current produces a magnetic field proportional to the amount of current flow. This magnetic field can be made stronger by winding the wire into a coil and further enhanced if done around an iron containing (ferrous) core.
| 3 Ω | |
| 10 Ω | |
| 15 Ω | |
| 30 Ω |
Ohm's law specifies the relationship between voltage (V), current (I), and resistance (R) in an electrical circuit: V = IR.
Solved for resistance, R = \( \frac{V}{I} \) = \( \frac{30}{3} \) = 10 Ω
The farad is a unit of measurement for:
power |
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capacitance |
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inductance |
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energy |
Capacitors store electricity and are used in circuits as temporary batteries. Capacitors are charged by DC current (AC current passes through a capacitor) and that stored charge can later be dissipated into the circuit as needed. Capacitors are often used to maintain power within a system when it is disconnected from its primary power source or to smooth out or filter voltage within a circuit.
The valence shell of a semiconductor is how full of electrons?
empty |
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half full |
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more than half full |
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less than half full |
Semiconductors have valence shells that are exacly half full and can conduct electricity under some conditions but not others. This property makes them useful for the control of electrical current.
The joule is a unit of measurement for:
power |
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energy |
|
resistance |
|
capacitance |
The joule is a unit of measurement for energy.