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Resistance
Question | Answer |
---|---|
Define resistance. | Ratio of voltage to current flowing through it |
What is the unit of resistance? | The Ohm |
What is an ohmic conductor? | A conductor whose resistance changes with voltage |
What is a practical resistor? | A resistor of a specific value |
What is another name for a variable resistor? | A rheostat |
What is the total resistance of a set of resistors in series? | The sum |
Name four factors that affect resistance. | Temperature. Length. Cross sectional area. Material of the conductor. |
What is the effect of increasing the temperature of a metallic conductor? | Resistance increases (linearly) |
What is the effect of increasing the temperature of a semi-conductor? | Resistance decreases |
What is a thermistor? | A semi-conductor whose resistance decreases rapidly with an increase in temperature |
What is resistivity? | The ratio of resistance by cross sectional area to length |
What is a wheatstone bridge? | A setup used to determine the resistance of a conductor using three resistors of known resistance |
Two uses of a wheatstone bridge. | Temperature control, fail safes |