Задача id13236

The image of the Sun was obtained using a lens consisting of a collecting and diverging lens (F1 = +10 cm, F2 = -10 cm), located at a distance l = 5 cm. A circular diaphragm with a diameter of D = 0.75 cm is placed in the middle between the lenses. Assuming that the lenses are large enough and do not limit the light beams, determine how many times the illumination of the image is greater than the illumination of the screen by direct sunlight. The angular diameter of the Sun a is taken equal to 0.01 rad. Neglect light losses in the lenses.

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