1) 72/4 = 18 years
2) 72/10 = 7.2 years
3) 72/13 = 5.54 years
Explanation: With the rule of 72, you simply take 72 and divide it by whatever the rate of return (or return on investment) is.
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Velocity = fλ
where f is frequency in Hz, and λ is wavelength in meters.
2.04 * 10⁸ m/s = 5.09 * 10¹⁴ Hz * λ
(2.04 * 10⁸ m/s) / (5.09 * 10¹⁴ Hz ) = λ
4.007*10⁻⁷ m = λ
The wavelength of the yellow light = 4.007*10⁻⁷ m
Answer:
The magnification is 133X
Explanation:
For a refractor telescope using convex lenses, the overall magnification os calculated as by dividing the focal length of the objective by that of the eyepiece.

So:

Care must be taken with the units, in this case they are in meters and centimeters, they should be converted into the same unit before calculating:

4) They have non-moving magnetic fields.