

MCQOPTIONS
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1. |
Laser light from a 2mW source of aperture diameter 1.5 cm and wavelength 5000 Å is focused by a lens of focal length 20 cm. The intensity of the image is __________ |
A. | 1.57 X 106 Wm-2 |
B. | 2.57 X 106 Wm-2 |
C. | 3.57 X 106 Wm-2 |
D. | 4.57 X 106 Wm-2 |
Answer» D. | |