When a thermistor is connected in series with a fixed resistor, how to explain the p.d. varies as resistance temperature changes?

When two components are connected in series, where one is a fixed resistor and the resistance of the other can vary (e.g. thermistor, light dependent diode, variable resistor etc), you always make use of the fixed resistor to explain the its p.d. as resistance is constant.

Then use the concept of sum of p.d. across both components is equal to the e.m.f of the circuit to explain how the p.d. across the other component varies.

Though thermistor is not in SciPhy syllabus, it can still be tested as long as the information on thermistor is given. Refer to the videos below where 2 are from Sciphy and the other is from Pure.

SP2020P2Q9

SP2013P2Q11

PP2008P2Q11OR

2012PPp1q7(c) - Determine the p.d. between points A and C

Basic Concepts on DC Circuit – River System

The ‘D.C.’ here mean direct current. It means that the current flows in one direction in the circuit.

The direction of the direct current refers to the conventional current, and it flows out of the positive (+) terminal of the cell / battery, around the circuit and flows back into the negative (-) terminal.

[Note: the direction of the electron flow is opposite to the conventional current]

To understand DC circuit, it will be useful to relate to a river system. Refer to the 3 videos below to learn more about

01: DC circuit similar to river system,

02: Series Circuit

03: Parallel Circuit and

04: Combined Circuit.

01: How is DC circuit related to a river system

02: Series Circuit

03: Parallel Circuit

04: Combined Circuit (Series and Parallel)

Now, after you have the basic concepts and rules for the circuits, let’s look at some simple example to reinforce you understanding.

Example 01: Series Circuit

Example 02: Parallel Circuit

Example 03: Combined Circuit

Example 04: PP2012P2Q7 DC circuit : pd across 2 points on two separate branches.