A simple magnifying glass can focus sunlight enough to heat up paper or dry grass and start a fire. A magnifying glass with a diameter of 4.2 cm has a focal length of 5.9 cm. The mean distance of the Sun from the Earth is 1.50 1011 m. The mean radius of the Sun is 6.96 108 m.
If the intensity of the Sun falling on the magnifying glass is 0.85 kW/m2, what is the intensity of the image of the Sun?