Resistor Online IGCSE Phyics Class
Resistor is a device that limits the flow of the current. The most commonly used film resistors can be divided into types according to the materials used: carbon-film, metal-alloy and metal-oxide.
Discuss the use of
- LDR / Photoresistor
- Varistor stands for “variable resistor” and is an electronic component.
- It is used to protect sensitive electronic devices and circuits from voltage spikes and transient overvoltage conditions.
- Their resistance decreases as the voltage across them increases
- When a voltage spike occurs, varistors rapidly change their resistance, becoming highly conductive and diverting excess current away from the protected circuit.
- A photoresistor, also known as a light-dependent resistor (LDR) or photocell, is an electronic component that changes its resistance based on the intensity of light falling on it.
- When exposed to light, the photoresistor’s resistance decreases, allowing more current to flow through it.
- In darkness or low light conditions, the resistance of the photoresistor increases, restricting the flow of current.
- They are commonly used in light-sensitive applications, such as automatic lighting systems, photographic light meters, and ambient light sensors in electronic devices
- A thermistor is an electronic component that changes its resistance with a change in temperature.
- It is made from a material that exhibits a significant change in resistance over a specific temperature range.
- NTC Thermistor – When the thermistor detects high temperature, the resistance decreases
- PTC Thermistor – When the thermistor detects high temperature, resistance increases