Question

Consider a bright star in our night sky. assume its distance from earth is 88.7 light-years (ly) and its power output is 4.00 x 1020 w, about 100 times that of the light-year is the distance traveled by light through a vacuum in one year. (a) find the intensity of the starlight at the earth. (b) find the power of the starlight the earth intercepts. (the radius of earth is 6.38 ✕ 106 m.)

Answer 1

The intensity of starlight at the Earth and the power of starlight intercepted by the Earth can be calculated using the inverse square law of light and the formula for power and area.

Step-by-step explanation:

(a) To find the intensity of the starlight at the earth, we can use the inverse square law of light. The intensity of light is inversely proportional to the square of the distance. Since the star is 88.7 light-years away, the intensity of the starlight at the earth would be 1/((88.7)^2) times the intensity at the source.

(b) To find the power of the starlight the earth intercepts, we can use the formula:

Power = Intensity x Area

Since the radius of the earth is given as 6.38 × 10^6 m, the area of the earth can be calculated using the formula for the area of a sphere: 4π(r^2). By substituting the values and multiplying, we can find the power of the starlight intercepted by the earth.