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Difference between Intensity and Irradiance

Hi y'all

In my sheets I am revising with in the run up to my Higher exam (Scotland). the words Irradiance and Intensity of light are being used interchangeably. I have a few questions...
1) Can I use both words? Or is there a 'favoured' word by the exam board?
2) What unit is it measured in? Watts per metre to the minus 1 or watts per metre to the minus 2?
3) What symbol is it in the exam sheets/data book?

As you can see, i've had very little info on it, just a few garbled equations and some stuff from memory. Any help is appreciated.

Thanks in advance

Reply 1

soup

Irradiance is a specific example of intensity for electromagnetic waves. So "irradiance" and "intensity of light" are the same, you will not get marked down. And it is the power per unit area so watts per square metre.

They'll have the formula booklet on their site so check for yourself what it is.

Reply 2

cchavez

is the irradiance (or intensity of light) the same when emitted in a continuous flux or a pulsed stream...like 100 Hz for example? Does the irradiance remains the same?