P3.2 Flashcards
What do you need to make a current flow
You need a potential difference (V)
Formula for energy transferred
Energy transferred (J) = potential difference (V) x charge (C)
What is the current in a series circuit
The current is the same everywhere in a series circuit.
How do you find the voltage across components
You connect voltmeters in parallel with the components to find the voltage across them.
What does voltage sum to in series
Voltage across components in series sums the voltage across the power supply/battery
What is voltage in parallel
The voltage across components in parallel is the same.
What does current do in parallel
The current splits at junctions and sums the total current
What is the formula for resistance in series and parallel
Rt = R1 + R2 - Series
1/RT = 1/R1 + 1/R2 - Parallel
What is resistance measured in
Ohms
Formula for voltage
V = IR
How is resistance produced
Resistance is produced when the delocalised electrons collide with the ions in the lattice.
What is the graph of current against P.D for a wire
the graph of current against P.D for a wire is a straight line through the origin
What is the graph of current against P.D for a lamp
A lamp is a non linear element as it’s resistance isn’t constant. This is because the electrons in a wire collide with the ions in the wire. The ions vibrate more as the wire gets hotter. There are more collisions as a result causing the current to increase as the P.D increases but at a slower rate.
What is the graph of current against P.D for a diode
A diode only allows current to flow in one direction and it only allows current to flow after 0.7V.
What does a thermistors’ resistance do
A thermistor is a resistor that depends on the temperature. The resistance of the thermistor decreases as the temperature increases.
