(a) What is the intensity in W/m² of a laser beam used to burn away cancerous tissue that, when 90.0% absorbed, puts 500 J of energy into a circular spot 2.3 mm in diameter in 3 s? 2 W/m (b) Reflect on how this intensity compares to the average intensity of sunlight (about 1W/m²) and the implications that would have if the laser beam entered your eye. Note how your answer depends on the time duration of the exposure. The intensity of a laser is abc lasers can be very damaging 100 1,000 10E7 - 10E8 10E12 times that of the sun, so clearly

The total rate at which power is used by humans worldwideis approximately 15 TW (terawatts). The solar flux averagedover the sunlit half of Earth is 680 W>m2 (assumingno clouds). The area of Earth’s disc as seen from the Sun is1.28 * 1014 m2. The surface area of Earth is approximately197,000,000 square miles. How much of Earth’s surfacewould we need to cover with solar energy collectors to powerthe planet for use by all humans? Assume that the solar energycollectors can convert only 10% of the available sunlightinto useful power.

Assume the intensity of solar radiation incident on the cloud tops of the Earth is 1 677 W/m². (a) Taking the average Earth-Sun separation to be 1.496 x 10¹1 m, calculate the total power radiated by the Sun. 4.905E26 x Your response is within 10% of the correct value. This may be due to roundoff error, or you could have a mistake in your calculation. Carry out all intermediate results to at least four-digit accuracy to minimize roundoff error. W (b) Determine the maximum value of the electric field in the sunlight at the Earth's location. kv/m (c) Determine the maximum value of the magnetic field in the sunlight at the Earth's location. μT

Radiation Energy The total radiation energy E emittedby a heated surface per unit area varies as the fourthpower of its absolute temperature T. The temperature is6000 K at the surface of the sun and 300 K at the surfaceof the earth.(a) How many times more radiation energy per unit area isproduced by the sun than by the earth?(b) The radius of the earth is 3960 mi, and the radius of thesun is 435,000 mi. How many times more total radiationdoes the sun emit than the earth?