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Component 1: Resistive components in circuits

4 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do an LDR and a thermistor turn light and temperature into a changing voltage?

Input sensors as variable resistors: the light-dependent resistor (LDR) and the NTC thermistor, how their resistance varies with light and temperature, and using them in a potential divider so the output voltage responds to the physical quantity.
A focused answer to WJEC Eduqas GCSE Electronics on input sensors, covering how an LDR and an NTC thermistor change resistance with light and temperature, and how a sensor in a potential divider produces a voltage that responds to the physical quantity.
9 min answer →

How does a potential divider produce a chosen output voltage, and how do we design one?

The potential divider: how two resistors share a supply voltage, the potential divider equation, and designing and analysing a divider to produce a required output voltage.
A focused answer to WJEC Eduqas GCSE Electronics on potential dividers, covering how two resistors share a supply voltage, the potential divider equation, and designing and analysing a divider for a required output voltage.
10 min answer →

Why do switches need pull-up or pull-down resistors, and how do we protect an LED with a series resistor?

Pull-up and pull-down resistors that give a switch a defined logic level, and the current-limiting (series) resistor that protects an LED, including calculating its value.
A focused answer to WJEC Eduqas GCSE Electronics on pull-up and pull-down resistors and current-limiting resistors, covering how a switch is given a defined logic level and how to calculate the series resistor that protects an LED.
9 min answer →

How do we calculate the total resistance of combined resistors and read a resistor's value and tolerance?

Calculating the total resistance of resistors in series and in parallel, and identifying a resistor's value, tolerance and power rating from its colour code or the E24 preferred-value series.
A focused answer to WJEC Eduqas GCSE Electronics on combining resistors, covering the total resistance of series and parallel resistors and reading a resistor's value, tolerance and power rating from colour codes and the E24 series.
9 min answer →