What is the unit for current? (DON’T NEED)
Amps
What is the unit for resistance?(DON’T NEED)
Ohms
What is the equation for charge?(DON’T NEED)
Q = I x T
Q = Charge flow - Coulombs I = Current - Amps T = Time - seconds
What is the equation for potential difference?(DON’T NEED)
V = I x R
V = Voltage - Volts I = Current - Amps R = Resistance - Ohms
What is the practical for investigating resistance?(DON’T NEED)
- Connect battery, ammeter and stripped wire in series.
- Attach the voltmeter in parallel with the crocodile clips
- Attach a crocodile clip at 0 cm.
- 2nd crocodile clip at 10 cm.
- Record the current and the voltage.
- Move 2nd crocodile clip another to 20 cm
- Record current and voltage
- Repeat for different lengths
- Then use the V = I x R to figure out the resistance
What are the rules in series circuits?(DON’T NEED)
- Current is the same at any point
- Voltage is shared between components (components with bigger resistance have bigger share of pd)
- Total resistance is the sum of the individual resistors
What are the rules in parallel circuits?(DON’T NEED)
- Current shared between branches (branch with less resistance has bigger share of current)
- Voltage is the same everywhere
- Total resistance is smaller than the smallest resistor
What is current?(DON’T NEED)
The rate of flow of charge
What is potential difference?(DON’T NEED)
The energy transferred per coulomb of charge between two points
What is a resistor?(DON’T NEED)
Resistance makes it harder for the current to flow
What is a thermistor?(DON’T NEED)
A resistor that decreases resistance as thermal energy increases
What is an LDR?(DON’T NEED)
A resistor that decreases resistance as the light intensity increases
What equation links current, voltage and power?(DON’T NEED)
P = I x V
P = Power I = Current V = Voltage
What is the shape of a graph with amps on the y axis and volts on the x axis for a filament lamp?(DON’T NEED)
An ‘S’ shape through the origin
What is the shape of a graph with amps on the y axis and volts on the x axis for a diode?(DON’T NEED)
The graph will be drawn in the upper right quadrant as diodes only allow current to flow in one way. Going up
What is the shape of a graph with amps on the y axis and volts on the x axis for a resistor?(DON’T NEED)
Linear line going through the origin with a positive correlation. Directly proportional
Carry out a practical for I - V characteristics(DON’T NEED)
1) Set up a circuit with a battery connected to a variable resistor with a component (lamp, diode or resistor) with an ammeter all in series. The voltmeter should be in parallel with the component.
2) Vary the resistance so that the voltage and the current changes
3) Take readings from the voltmeter and the ammeter and record the results in a table
4) Swap over the wires connected to the battery, so the direction of the current is reversed.
5) Plot a graph
