Chapter 9 - energy, power and resistance Flashcards
should voltmeters be connected in series or parallel
parallel
what is potential difference
the work done per unit charge
what does ε represent
electromotive force
equation relating energy transferred to voltage
W = VQ
what is resistance
a measure of how difficult it is for current to flow through an appliance
what’s an ohmic conductor
a conductor which obeys Ohm’s Law
Ohm’s Law
the current through an ohmic conductor is directly proportional to the potential difference across it
what does gradient of current-potential difference graph represent
1/R
what is a diode
an appliance which allows current to only flow in one direction
what is a light-dependant resistor
a semi-conductor which is sensitive to light
how does a thermistor work
as temperature increases, resistance decreases
what is electromotive force used to measure
the work done to charge carriers
electron gun purpose
used to produce a thin beam of electrons, which travel at high speeds
how to determine resistance of a component
-variable power supply
-ammeter in series with the component being measured
-voltmeter in parallel with component
-varied power supply means a variable potential difference across the component
-record potential difference and current
-plot a graph of pd against current
-resistance is 1/gradient
what happens when light intensity on resistor is increased
resistance of LDR decreases
