Tag Archive for: radiation

Thermal Selfies

Today Think Physics was visiting The Hermitage Academy STEM fair.  It was lovely to chat with the people of Chester-le-Street and beyond.

We took with us our thermal camera and plasma ball, both of which we use as part of the ‘Explore your Universe’ workshops (which are available for booking!).  Our theme was ‘seeing things differently’ and we were offering ‘Thermal Selfies’.  Now, technically, they were infrared photographs – but we decided to go with the catchy title.

We looked at the different types of information that we could get by using different wavelengths of light: visible, infrared and UV.  With the IR camera we could measure the temperature of body parts and see who had cold noses.  We could also look at how effective coats and jackets were at keeping people warm, by looking at how much IR was radiated by them.

The IR camera allows us to demonstrate why astronomers use telescopes to observe different wavelengths of light by using a black bin bag to simulate interstellar dust.  In visible light, we couldn’t see through it, but in IR we could see the children hiding very easily.  A handy gadget for our next game of hide and seek!


Hiding behind a black plastic bag? Not in infrared!

We also looked at how the sun appears in different wavelengths, comparing the slightly boring visible light pictures with the more interesting UV pictures.

Visible light images of the sun. NASA

Visible light images of the sun. NASA

UV images of the sun. NASA

UV images of the sun. NASA

Thank you very much to Ms Rose at the Hermitage Academy for inviting us along to the STEM fair.  We had a great time taking thermal selfies and talking physics.  As promised, we have put together a gallery of the pictures.  If there’s one of you, can you spot it?


Tag Archive for: radiation

Inverse Square Law

A-Level Physics Required Practicals:
Inverse Square Law

Supporting notes for this film will follow shortly.


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Student Worksheet

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Comments & Feedback

As ever, no single film can encompass everything one might wish to say about a practical. Please, leave comments with your thoughts about the approach we’ve taken, and your suggestions for alternatives or improvements.

Tag Archive for: radiation


Employer: Kromek Ltd

Who Are They?

Kromek design and make radiation detectors using a crystal called cadmium zinc telluride (CZT).  The detectors can measure the amount and type of radiation in an area or being emitted by an object.  This information can then be processed and analysed by computer.

In medicine, the radiation detectors are used with gamma and X-ray machines to develop an image of internal organs and see what is happening in the body.  They can also be used to measure bone density which is important in diagnosing osteoporosis in older people.

For security, the detectors are small enough that they can be worn by security officers as they go about their normal duties.  Using a smart phone app, the detectors allow a ‘map’ of radiation to be drawn in real-time.  If the levels of radiation go above background radiation, then the detectors let the officer know what the radiation is, and whether it is a threat.

Kromek detectors are also being used to scan and identify potentially explosive liquids at airports.  The detector compares the results of each scan with a database of known compounds (e.g. duty free alcohol, baby food, explosives) to identify liquids which you would not want someone to take on a plane!


Kromek need a range of different roles to design, build, test and sell their detectors. Some staff have PhDs in physics and materials science, but that isn’t necessary to work in a technology company.

Some typical roles are:

  • Gamma Scientist
  • Radiation Detector Physicist
  • Product design engineer
  • Digital marketing
  • Software engineer
  • Process engineer
  • Electronics engineer
  • Buyer
  • Management accountant
  • Test engineer

Science and Maths links

Topics that link to Kromek and what the company does:

  • Nuclear radiation and structure of the atom
  • Electromagnetic spectrum
  • Conductors, semi-conductors and insulators
  • Probability and random numbers

Tag Archive for: radiation

11th May – Peake Radiation

Hey St Mary’s! If everything has gone to plan, as you read this, I will be right in front of you IRL, as you kids say.

Here’s the link to the radioactive dating game.

Here’s the data from the ISS: –

And here’s an interactive video of the Falcon 9 vertically landing on a drone ship. Because it’s awesome.