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The illumination on the screen, in case of a movie hall if the distance between the
projector and the screen are increased by $ 1 \% $ will be:
(A) increased by $ 1 \% $
(B) decreased by $ 1 \% $
(C) increased by $ 2 \% $
(D) decreased by $ 2 \% $

seo-qna
Last updated date: 20th Jun 2024
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Answer
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Hint
A projector is an output device that projects an image onto a large surface, such as a white screen or wall. Most projectors have multiple input sources, such as HDMI ports for newer equipment and VGA ports for older devices. A projector is an optical gadget that projects a picture or moving images onto a surface, usually a projection screen. Most projectors create a photo through projecting a bright light via a small lens. However, some newer types of projectors can project the image directly, by using the usage of lasers. Based on this we have to solve this question.

Complete step by step answer
We know that,
Projector acts as a point source,
Hence, $ \mathrm{E} \propto \dfrac{1}{\mathrm{r}^{2}} $
 $ \dfrac{\mathrm{dE}}{\mathrm{E}}=2\left(\dfrac{\Delta \mathrm{r}}{\mathrm{r}}\right)=2 \times 1 \%=2 \% $
As the distance increases, the illumination will decrease.
Therefore, the correct answer is Option (D).

Note
It should be known to us that lighting or illumination is the deliberate use of light to achieve practical or aesthetic effects. Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as natural illumination by capturing daylight. During the day, the sun generates sufficient light to illuminate objects on Earth. The irregular reflection of light from the object makes it appear bright. Non-luminous objects reflect the light falling on them and the reflected light is sensed by the eye and thus we are able to see non-luminous objects.