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SingaporeElectronics

Sensors and Transducers

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

How do a light-dependent resistor and a thermistor turn light and temperature into an electrical signal a circuit can use?

Describe the LDR and the thermistor as input transducers, state how their resistance changes, and use them in a potential divider
A focused answer to the O-Level Electronics outcome on input transducers. How the LDR and thermistor change resistance with light and temperature, and how they produce a varying voltage in a divider.
8 min answer →

How does a circuit turn its electrical output back into something we can see, hear or use, such as light, sound or movement?

Describe common output transducers (lamp, LED, buzzer, motor, loudspeaker) and the energy conversion each one performs
A focused answer to the O-Level Electronics outcome on output transducers. The lamp, LED, buzzer, loudspeaker and motor, the energy each converts, and how they are driven from a circuit.
7 min answer →

How do switches and variable resistors act as inputs to a circuit, and how does a switch produce a clean logic signal?

Describe switches and variable resistors as input devices and explain how a switch with a pull-down resistor gives a logic input
A focused answer to the O-Level Electronics outcome on switch and variable-resistor inputs. Switch types, the pull-down resistor for a clean logic level, and the potentiometer as an adjustable input.
8 min answer →

How can a small electronic signal safely switch a large or mains-powered load, and why is a protective diode needed?

Explain how a relay lets a small current switch a large or isolated load and why a flyback diode is connected across the coil
A focused answer to the O-Level Electronics outcome on relays. How a relay switches a large or isolated load from a small current, and why a protective flyback diode is placed across the coil.
8 min answer →