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# Determine the ratio of light intensity.?

The magnitude M of a star is modeled by: M = 6 - 5/2 log I/Io

Where Io is the intensity of a just-visible star and I is the actual intensity of the star being measured. The dimmest stars are of magnitude 6, and the brightest are of magnitude 1. Determine the ratio of light intensities between a star of magnitude 1 and a star of magnitude 3.

Could you please explain the steps to the answer.

### 2 Answers

- Anonymous1 decade agoFavorite Answer
Solve for the ratio l/lo:

l/lo = 10^((6-M) * 2/5)

Now if intensity for M=1 is l1 and intensity for M=3 is I3 then the ratio:

(l1/lo) / (l3/lo) will become l1/l3 since lo on both sides of the division operator will cancel each other. This ratio (l1/l3) is what we're looking for!

Now look at the other side of the equation:

(10^((6-1) * 2/5)) / (10^((6-3) * 2/5)) = 10^2 / 10^1.2 = 10^(2-1.2) = 10^0.8 or roughly 6.3 times greater intensity for M=1 as M=3. Please check my calculations as they were scribbled down at speed.

- Anonymous4 years ago
Use an Ohm Meter to degree the changing resistance of the LDR. Then use a mild source which you would be able to regulate. some thing like a flashlight bulb and batteries. Use an adjustable resistor to selection the sunshine intensity. The Ohm meter will demonstrate the outcomes that with the sunshine intensity.