Table of Contents

## What are the applications of thermistor?

Common Thermistor Applications Thermistors are used as temperature sensors. They can be found in every day appliances such as fire alarms, ovens and refrigerators. They are also used in digital thermometers and in many automotive applications to measure temperature.

**What does it mean to have a non linear relationship between current and voltage?**

In circuits where resistance varies with changes in either voltage or current, the plot of current over voltage will be nonlinear (not a straight line). Negative resistance is where the current through a component actually decreases as the applied voltage across it is increased.

**How would you describe the relationship between the current and the voltage in a circuit?**

This equation, i = v/r, tells us that the current, i, flowing through a circuit is directly proportional to the voltage, v, and inversely proportional to the resistance, r. In other words, if we increase the voltage, then the current will increase. But, if we increase the resistance, then the current will decrease.

### How is resistance affected by a change in temperature of the wire and why?

Resistance increases with the temperature of the wire. When a material gets hotter the atoms in the lattice vibrate more. This makes it difficult for the electrons to move without interaction with an atom and increases resistance.

**What is the application of thermistor Insensing circuit?**

A thermistor is a specific type of resistor that uses sensors to help regulate cold and heat. They can do more then simply regulate temperature. They are also used for voltage regulation, volume control, time delays, and circuit protection.

**What are different types of thermistor and what are their applications?**

The main two types of thermistors are NTC (Negative Temperature Coefficient) and PTC (Positive temperature coefficient). Thermistors measure temperature by using resistance. With an NTC thermistor, as the temperature increases the resistance decreases, and when the temperature decreases, the resistance increases.

#### Is there a linear relationship between current and voltage?

The simplest I–V curve is that of a resistor, which according to Ohm’s law exhibits a linear relationship between the applied voltage and the resulting electric current; the current is proportional to the voltage, so the I–V curve is a straight line through the origin with positive slope.

**Are voltage and current linear?**

We will assume for now that any resistor we use is operating within a range of voltages and currents over which its voltage-current characteristic is linear and can be approximated by equation (1).

**How do you control the temperature of a wire?**

They control the heat in one of several ways:

- Switching between different wires.
- Switching between wires in single, serial or parallel.
- Pulsing the power through the wire using a triac.

## What is the principle of the thermistor?

The thermistor works on the simple principle of change in resistance due to a change in temperature. When the ambient temperature changes the thermistor starts self-heating its elements. its resistance value is changed with respect to this change in temperature.

**Which is a non linear characteristic of the thermistor?**

The thermistor exhibits a highly non-linear characteristic of resistance vs. temperature. PTC thermistors can be used as heating elements in small temperature controlled ovens. NTC thermistors can be used as inrush current limiting devices in power supply circuits.

**Is the plot of current over voltage linear or nonlinear?**

Any function that can be plotted on a graph as a straight line is called a linear function. For circuits with stable resistances, the plot of current over voltage is linear (I=E/R). In circuits where resistance varies with changes in either voltage or current, the plot of current over voltage will be nonlinear (not a straight line).

### Which is circuit component provides a nonlinear resistance curve?

There are circuit components specifically engineered to provide nonlinear resistance curves, one of them being the varistor.

**How does conductor resistance change with the temperature?**

One of the phenomena explored in a later chapter is that of conductor resistance changing with temperature.