Final answer:
The average intensity of the laser beam is calculated using the provided power and the cross-sectional area of the beam. With a power of 0.10 mW and a diameter of 0.90 mm, the calculated intensity is approximately 157 W/m².
Step-by-step explanation:
To find the average intensity of a laser beam, we use the formula:
I = P / A
where I is the intensity, P is the power of the laser, and A is the area of the beam's cross section.
The power (P) provided is 0.10-mW (or 0.10 x 10-3 W). The diameter of the beam is 0.90 mm, so the radius (r) is half of that, 0.45 mm or 0.45 x 10-3 m. The area of the beam's cross section can be found using the area formula for a circle:
A = πr2
Substituting the values we have:
A = π * (0.45 x 10-3 m)2 = π * (0.452 x 10-6 m2) = 6.36 x 10-7 m2 (approximately)
Now, we calculate the intensity:
I = (0.10 x 10-3 W) / (6.36 x 10-7 m2) = 1.57 x 102 W/m2 (approximately)
Hence, the average intensity of the laser beam is approximately 157 W/m2.