Grade 77 grade science

How does digital thermometer measure temperature? Explain

Ranjana

8 Years agoGrade 7

4 Answers

Ayush Anand

8 Years ago

They`re based on the idea that the resistance of a piece of metal (the ease with which electricity flows through it) changes as the temperature changes. As metals get hotter, atoms vibrate more inside them, it`s harder for electricity to flow, and the resistance increases. Similarly, as metals cool down, the electrons move more freely and the resistance goes down. (At temperatures close to absolute zero, the lowest theoretically possible temperature of −273.15°C or −459.67°F, resistance disappears entirely in a phenomenon called superconductivity.)A digital thermometer works by putting a voltage across its metal probe and measuring how much current flows through it.A microchip inside the thermometer measures the resistance and converts it into a measurement of temperature.

Scholr Boy

7 Years ago

Use Scholr App for solving doubts

With electronics, if you want to measure temperature you need a sensor or transducer as we prefer to call them that changes electrical properties with temperature. There are actually many ways to do this - we have thermocouples that put out a small microvoltage voltage proportional to the temerpture, we have RTD which change resistance, we have semiconductors in which the V/I curve is a function of temperature. We can also measure the infrared signal strength off a surface for non-contact measurement. The trick then is to get the analog electrical phenomena converted to a analog voltage and then use an analog-to-digital conversion to display the value which has to be properly scaled to the units system or send to a computer.