At the focus of a converging lens with focal length F = 10 cm there is a point source of light. At a distance L = 1 m from the lens, a screen is placed perpendicular to the optical axis of the lens. How many times is the illumination in the center of the light spot resulting on the screen greater than the illumination in the same place on the screen created by the source in the absence of a lens? Neglect light losses in the air and in the lens.

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