A planet orbits a nearby star.
The power output of the star is 1.2 × 1026 W. The average distance of the planet from the star is 1.8 × 1011 m.
The intensity of radiation, III, at a distance d d\,d from a star of power P P\,P can be calculated using the equation:
I=P4πd2 I = \frac{P}{4 \pi d^2} I=4πd2PCalculate the intensity of the radiation from the star at the planet's orbit.
Give your answer to 2 significant figures and state the appropriate unit.
28 exam-style questions on Edexcel GCSE Physics 7.1 The Solar System and gravity, covering 7.1.1 Weight and g on different bodies in space, 7.1.2 The Solar System, 7.1.3 Changing ideas about the Solar System, 7.1.4 Orbits of moons, planets, comets and satellites, and 7.1.5 Gravity and orbital motion. Each one has a worked solution and a mark scheme showing where the marks go.