Ocr As Level Physics: Energy, Power And Resistance Study Guide Rated A+

Why does increased temperature increase resistance? {Ans: Positive ions have more internal energy, frequency of collisions between ions and electrons increases, charge carriers do more work}What happens to resistivity as temperature increases in a metal? {Ans: Increases}Features of the I-V characteristic of a diode {Ans: Potential difference isn't directly proportional to the current in the resistor, non-ohmic, resistance not constant, depends on polarity}How LDRs work {Ans: Light raises the number density of free electrons}Important feature of resistance-current graph {Ans: Non-zero intercept}Issues with determining resistivity experimentally {Ans: Hard to do if high conductance wire is used as R is so low, resistance of wires and croc clips becomes significant}Negative temperature coefficient {Ans: Resistance drops as temperature rises}Unit of resistance {Ans: Ohm}Resistance is inversely proportional to... {Ans: 1/Area}Equation for resistance {Ans: Resistance = Voltage / Current}Equation for kWh {Ans: Energy transferred = Power x Time}Unit of potential difference {Ans: Volt}Difference between potential difference and electromotive force {Ans: Potential difference is energy transferred from electrical energy to other forms whereas electromotive force is energy transferred from chemical energy to electrical energy}Resistance is directly proportional to... {Ans: Length}As light intensity