1. Starting from Maxwell's equations, derive a wave equation for the magnetic field and show that a harmonic plane wave prorogating along x direction is a solution. Prove it is a transverse wave. 2. Consider sunlight at the top of Earth's atmosphere. The sun-earth distance is 500 light-second. The sun's total power radiation is 3.9×1026 W. (1) What is the sunlight intensity? (2) What is the electric field amplitude? (3) How does its magnetic field amplitude compare to the Earth's magnetic field?

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