# The aim of my Hot Water Tap Thermometer is to create an electronic thermometer that will accurately measure the Hot Water Tap's water temperature.

Hot Water Tap Thermometer

Context

It can be dangerous when placing your hand under a hot water tap, as you can never tell if the water is going to be too hot or not. The water can cause some scalding to the skin. I have researched and found that the average hot water temp is 50 oc. And that the skin can be scaled above 60 oc.

Aim

The aim of my Hot Water Tap Thermometer is to create an electronic thermometer that will accurately measure the Hot Water Tap’s water temperature. I am going to use an electronic circuit to measure the temperature and use the voltage to calculate the temperature.

Theory of Semi-Conductors

At ordinary temperatures, they only have a few free electrons. As the temperature increases more electrons are liberated

In insulators the energy gap between the two bands is large, so they have few electrons in the conductor band (this means no conduction can happen.) in semi-conductors energy bands close to the conduction bands are created. When heated enough energy is given to electrons to move the conduction band and the current increases. (Resistance drops)

## N and P type Semi Conductors

N type = Charge Carriers are electrons (negative)

Silicon (Si) is doped with phosphorus to give “excess” electrons, which are used in conduction.

P type = Charge carriers are “holes” (positive)

### Thermistors

A Thermistors is a small electrical component that measures temperature. It is a semi-conductor so when the Temperature increases the resistance drops. Thermistors can be used in a potential divider circuit to create different voltage outputs.

#### Ohm’s Law

Ohm’s Law is a law that connects V (voltage), I (current) and R (resistance). This means that if you have any two of these you can calculate the 3rd.

Prediction

I think that there will be an inversely proportional connection between the Temperature and the Voltage. So as the water temperature increases the voltage recorded will ...