These electrical components decrease their resistance when the light intensity increases.This example asks you to read data from a graph to answer the question.Thermistors (thermal resistors) change their resistance with temperature, the hotter it gets the lower the resistance.In this example you need to read the graph to find the data needed for the equation.The reason you should know about these components is because they can be used in sensing circuits, to change what happens if it gets too hot, cold, dark or light.The following organisations have recently recommended these resources to support students who are learning from home during the Covid-19 crisis.If you enjoy physics then find hundreds more videos at A Level Physics Online.com All resistors vary with temperature, but thermistors are constructed of a semiconductor material which behave differently to normal metallic conductors. A thermistor is a thermally sensitive ceramic semiconductor which exhibits a change in resistance as the temperature changes. In this GCSE Physics video we look at thermistors.
Notice how the resistance drops from 100 kW, to a very small value in a range around room temperature. This is due to the properties of the semiconductor material that the thermistor is made from. Thermistor: Example. We explain the difference between Positive Temperature Coefficient (PTC) & Negative Temperature Coefficient (NTC) thermistors. We then explore how resistors can be used in electrical circuits. For some, this may be counterintuitive, but it is correct. Thermistors (thermal resistors) change their resistance with temperature, the hotter it gets the lower the resistance. How does a Thermistor Work? Post was not sent - check your email addresses! The Thermistor . increases, the current flow also increases to start with (as we’d expect). GCSE Physics Paper 1 Thermistors. In light dependent resistors, this energy is light and in thermistors it is heat.Thermistors are temperature sensitive resistors. Ohmic conductors In an ohmic conductor, free electrons carry the current when a potential difference is applied across it. This in turn leads to a greater resistance slowing the flow of electrons so a smaller current flows.In semiconductors as the energy given increases, more free electrons are let free and so a current increases and the resistance goes down. Not only is the resistance change in the opposite direction from what you expect, but the magnitude of the percentage resistance change is substantial.Positive temperature coefficient thermistors do exist but are typically made from just normal conductors, like a metal wire. 5. New here? Here is a graph of resistance as a function of temperature for a typical thermistor. Thermistors: this article defines & describes thermistors, thermal-sensitive resistors that respond to temperature changes, permitting very precise temperature measurement and the use of temperature to control devices such as room thermostats or process controllers.