The sun emits electromagnetic waves with a power of 4.0 * 10²⁶ W. Determine the intensity of electromagnetic waves from the sun just outside the atmospheres of (a) Venus, (b) Mars, and (c) Saturn. Refer to the table of astronomical data inside the back cover.

I_v = 2,700 W / m^2

I_m = 610 W / m^2

I_s = 16 W / m^2

Explanation:

Given:

- The Power of EM waves emitted by Sun P_s = 4.0*10^26 W

- Radius of Venus r_v = 1.08 * 10^11 m

- Radius of Mars r_m = 2.28 * 10^11 m

- Radius of Saturn r_s = 1.43 * 10^12 m

Find:

Determine the intensity of electromagnetic waves from the sun just outside the atmospheres of (a) Venus, (b) Mars, and (c) Saturn.

Solution:

- We know that Power is related to intensity and surface area of an object follows:

I = P / 4*pi*r^2

Where, A is the surface area of a sphere models the atmosphere around the planets.

a)

- The intensity at the surface of Venus is calculated as:

I_v = P_s / 4*pi*r^2_v

I_v = 4.0*10^26 / 4*pi * (1.08*10^11) ^2

I_v = 2,700 W / m^2

b)

- The intensity at the surface of Mars is calculated as:

I_m = P_s / 4*pi*r^2_m

I_m = 4.0*10^26 / 4*pi * (2.28*10^11) ^2

I_m = 610 W / m^2

c)

- The intensity at the surface of Saturn is calculated as:

I_s = P_s / 4*pi*r^2_s

I_s = 4.0*10^26 / 4*pi * (1.43*10^12) ^2

I_s = 16 W / m^2