A star radiates isotropically with luminosity 2.80 × 10^27 W. An observer is 4.00 × 10^17 m away. Calculate the received flux and state the flux at twice this distance.

1.39 × 10^-9 W m⁻²; at twice the distance 3.48 × 10^-10 W m⁻² The luminosity spreads over a sphere of area 4πd². F = L/(4πd²) = 1.39 × 10^-9 W m⁻². Doubling d multiplies area by four, so flux becomes F/4 = 3.48 × 10^-10 W m⁻².

IB Physics · E.5 · extended response

Stellar luminosity and flux 4

Nuclear and quantum physics · Fusion and stars · Original GioPhysics question with a detailed, mark-by-mark answer guide.

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Marks: 6
Topics: 2
Answer: Complete

Question6 marks

A star radiates isotropically with luminosity 2.80 × 10²⁷ W. An observer is 4.00 × 10¹⁷ m away. Calculate the received flux and state the flux at twice this distance.

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Response type: extended response
Allocation: 6 marks
Demand: demanding

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