1.

Laser light from a 7mW source of aperture diameter 1.5 cm and wavelength 5000 is focused by a lens of focal length 10 cm. The intensity of the image is __________

A. 3 X 10<sup>7</sup> Wm<sup>-2</sup>
B. 4 X 10<sup>7</sup> Wm<sup>-2</sup>
C. 5 X 10<sup>7</sup> Wm<sup>-2</sup>
D. 6 X 10<sup>7</sup> Wm<sup>-2</sup>
Answer» D. 6 X 10<sup>7</sup> Wm<sup>-2</sup>


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