How practical is solar power for various devices? Assume that on a sunny day, sunlight has an intensity of at the surface of Earth and that a solar-cell panel can convert 20% of that sunlight into electric power. Calculate the area A of solar panel needed to power
(a) A calculator that consumes 50mW,
(b) A hair dryer that consumes 1500W,
(c) A car that would require 40 hp.
(d) In each case, would the area A be small enough to be mounted on the device itself, or in the case of (b) on the roof of a house?