Electricity 2 Flashcards
List the factors that affect the heat produced in a current-carrying conductor.
- Resistance
- Current squared
- Time
Define resistivity.
The resistance of the conductor of length 1m and cross-sectional area 1m2. The unit is ohm metre.
Name the device in the circuit that is used to vary the potential difference across the conductor.
A potential divide
Explain how the student used the potential divider to vary the potential difference.
Move the sliding contact to very the potential difference across the metallic conductor.
In an experiment to verify Joule’s law, explain why a fixed mass of water was used.
This experiment examines the relationship between current squared and temperature. All other variables such as mass of water must be held constant.
How would an observer know that a Wheatstone bridge is balanced?
The galvanometer would read zero. No current flows through the galvanometer.
What is a semiconductor?
A material with a conductivity or resistivity between that of a conductor and an insulator.
Distinguish between intrinsic and extrinsic conduction in a semiconductor.
I: The semiconductor is pure and the number of holes and electrons are equal.
E: The semiconductor is doped and the number of electrons and holes arae not equal.
Explain how a pure semiconductor can be converted into a p-type semiconductor.
Doping with a group III element.
Explain how a pure semiconductor can be converted into an n-type semiconductor.
Doping with a group V element.
What is the function of a rectifier?
Converts a.c. to d.c
What property of a diode makes it useful in a rectifier circuit?
Allows current to flow in only one direction.
Explain how a diode might be protected from having too large a current flowing through it when it is connected across a battery.
Connecting a resistor in series with the diode will protect it.
What would be the effect on the current flowing in this diode if the terminals of the battery were reversed. Explain your answer.
If the terminals of the battery are reversed either no current or a very small current flows, as the diode is now reversed biased.
What is meant by rms?
Root-mean-square
