Interesting temperature measurements using an infrared thermometer

Earlier this year I purchased one of those infrared thermometers that you just point at things and pull a trigger to measure its temperature. Initially I had plans to use it to make the perfect cup of coffee. Well, that didn’t work out very well as the thermometer had difficulties measuring the temperature of the liquid and the shiny container. Even if it had worked the coffee probably would have still been far from perfect. I soon discovered that it is more fun using the thermometer to measure the temperature of random objects. These thermometers measure heat using infrared light. They don’t have to come into contact with an object as they measure the infrared energy that naturally radiates from it.

My thermometer - $20 from ebay

The sky

Pointing directly up into the winter sky in the afternoon gave a reading -47°C (-52°F). I found this interesting as it is not measuring an object. I assume it is just reading the amount of infrared light it can detect in the atmosphere above.

Thermometer pointing into the sky

Frost covered car

The back of the car on a cold frosty morning is -9°C (16°F). No wonder it feels cold when I get into it in the morning. That louver on the rear window makes it look cooler – A bit like the Delorian don’t you think 🙂

Thermometer pointing to the rear of a car

Frost covered flower

Probably the coldest morning of the year. The official temperature nearby was -9°C. We usually experience a bit colder temperatures here. This flower is -12°C (10°F). It’s no surprise that so many plants from other parts of Australia do not grow here.

Thermometer pointing at a frost covered pansy

Wood heater

Temperatures at the top got up to 457°C (854°F). Not a place you would want to place your hand. This is a significant difference with our reverse cycle air conditioner. When it is heating it blows warm air whereas this heater is hot.

Thermometer pointing at the top of a wood heater

Cat laying in front of the heater

Our cat loves heat and has very fine black fur. Here the fur is showing 60°C (140°F). I think the fur makes a good insulator so the cat is nowhere near as hot as this reading indicates.

Thermometer pointing at a cat laying in front of the wood heater

Cat laying in the sun

Here it is lying in the sun. I find it interesting that its fur is hotter that when it was in front of the wood heater 66°C (151°F).

Thermometer pointing at cat laying in sunshine

Regular Toast

Toast is pretty hot when it pops up. Picking it up immediately after it popped up shows it to be 123°C (253°F). Why don’t we get burned? Maybe it’s because the toast is a good insulator. Perhaps it is because the toast has a porous texture that it has a large surface area that accelerates its cooling. It certainly cools quite quickly. I don’t know really.

Thermometer pointing at a slice of taost that has just popped out of a toaster

Raisin Toast

The raisin toast is even hotter 167°C (333°F). Perhaps a raisin is influencing the reading here.

Thermometer pointing at a slice of raisin toast that has just popped out of a toaster

Other things to try

Some other fun and interesting things to try if you get a chance to use one of these are:

  • Heaters
  • Light bulbs
  • Windows, doors and walls outside at night. Leaking heat will be obvious by higher temperature readings
  • The sky at different times of the day and night
  • Food in different areas of a fridge and freezer

Posted on August 26, 2012, in House and Garden, Science and tagged , , , , , , , . Bookmark the permalink. 1 Comment.

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