Potential Divider
What is a potential divider
When 2 or more resistors are connected in series with a source of fixed PD
Define EMF
The transfer of chemical energy to electrical energy causing work done per unit coulomb
How to supply a fixed PD using a PD divider ?
Attach a PD supply to 2 or more resistors in series. V = V0R1 / RT Combine resistors in a way to supply desired PD
State Kirchhoff's first law
At any junction, total current entering the junction = total current exiting the junction.
What are some uses for a variable pd divider ?
Adjustable volume
Adjustable brightness
Adjustable throttle
State Kirchhoff's second law
For any complete loop in a circuit, sum of emfs = sum of potential drops
How to supply a variable pd ?
Use a fixed length of uniform resistance wire with a contact slider. Length is proportional to R, and R is proportional to V, so increasing length increased Voltage
State the equation for cell current
Cell current = Cell emf / total circuit resistance
How to sensor circuits work ?
Thermistor or LDR. Increase in T or Light Intensity (l) results in decrease in V ( as T/l are inversely proportional to R )