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What is "half-life"?

Half-life is a term commonly used in radioactivity. It defines the time taken for a radioactive source to halve its activity. A radioactive source will emit radiation (energy) through the emission of particl...
ET
Answered by Evan T. • Physics tutor
5170 Views

A given star has a peak emission wavelength of 60nm, lies 7.10*10^19m away and the intensity of its electromagnetic radiation reaching the Earth is 3.33*10^-8Wm^-2. Calculate the star's diameter

With a problem like this, the key is to split it down into component parts. We will treat the star as a perfect emitter and radiator, something known as a black body. There will be two physical laws we need ...
JS
Answered by James S. • Physics tutor
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Why is the sky blue?

The colour of the sky comes from sunlight scattering off of the air molecules (and to your eyes). Blue light gets scattered more than red light because it has a shorter wavelength, and so the light you see w...
AP
Answered by Alex P. • Physics tutor
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How do I find the half-life of radioactive isotope?

The half-life of a radioactive isotope is the time taken for half of the atoms in a given sample of the isotope to decay. Radioactivity is random and so, half-life is the average time taken for a large numbe...
JS
Answered by Joe S. • Physics tutor
18383 Views

How does a thermal nuclear reactor work?

The thermal nuclear reactor is one of many systems used to produce energy (electricity). Like many systems (furnaces for example) it does this by heating water to produce steam. This steam drives turbines wh...
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Answered by James A. • Physics tutor
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