Potential Divider Circuits

Question 1

Features of a Potential Divider Circuit

Answer 1

V(In) is the P.D. of the fixed power supply
V(Out) is the P.D. across R(2) -> Fraction of the V(In)
Total Resistance is R(1) + R(2)
Current is Constant

Question 2

Potential Divider Equation

Answer 2

V(Out) R(2) / R(Total) x V(in)

Question 3

Potential Divider Ratios

Answer 3

V1/V2 = R1/R2

Question 4

Potential Divider Using Current

Answer 4

Calculate Current
Use V = IR

Question 5

Potentiometer (Rheostat)

Answer 5

Potential Divider Circuit
R(2) Varies from Max at Contact A and Zero at Contact B
Current is constant
Varies Resistance and therefore V(Out)

Question 6

Thermistors

Answer 6

Used in Temperature sensing circuits
Fridges, Ovens or Heating Controls
NTC (Negative Temperature Coefficient)
As Temperature increases, resistance deceases
Semiconductor - Number Density Increases with Temperature
In a circuit with a fixed resistor, it’s voltage share depends on the Temperature
V(In) Shared between Resistors

Question 7

Temperature Changes

Answer 7

If T increases, Thermistor Resistance Decreases, so Total Resistance Decreases. So current increases
V(Out): The P.D. Share of thermistor decreases. So V(Out) increases as V(In) is constant

Question 8

Temperature Sensing Circuits

Answer 8

Used in circuits controlled by temperature changes
Low temps: Small change in T causes a large change in R
Sensitive at Lower Temperatures -> Useful in Fridges

Question 9

Light Dependent Resistor (LDR)

Answer 9

Resistance changes with light intensity
If Light Intensity increases -> Decreases R and P.D.
Light Bulb Goes off and Vice Versa
If V increases, Light Bulb turns on, meaning Light intensity increases and Lower R and V, so light turns off