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(i) By comparing with the luminosity of the Sun, calculate the absolute magnitude of a 60W light bulb.

[The absolute magnitude of the Sun is +4:75; you may ignore colour differences

between the bulb and the Sun.]

(ii) The Hubble Space Telescope (HST) can detect objects as faint as 30th magnitude.

Calculate the maximum distance in kilometres at which the light bulb could be

detected by HST.

(i). can anyone give me any hints for this. i know the formula for two absolute magnitude and the formula for the luminsoity, but not sure how to use them, as we aren't told the luminosity of the bulb.

(ii). we know the absolute magnitude (1/30), and so this is measured at 10 pcs. so do they just want use to calculate 10 pc in metres?

thanks for any help.

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# How to calc absolute magnitudes by comparing to the sun's luminosity

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