A student obtained a sharp image of the grills of a window on a screen...
When the image distance increases, object distance decreases. Thus, distance between the mirror and screen will decrease. So, the mirror should be moved towards the screen.
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A student obtained a sharp image of the grills of a window on a screen...
Explanation:
When using a concave mirror, the teacher suggests focusing a well-lit distant object on the screen to obtain better results when imaging the grills of a window. This can be achieved by moving the mirror slightly towards the screen.
Why moving the mirror towards the screen is the correct answer?
When a concave mirror is used, the image formed depends on the position of the object (the grills of the window) and the position of the screen. By moving the mirror slightly towards the screen, the distance between the mirror and the screen decreases. This has the following effects:
1. Increase in magnification: Moving the mirror closer to the screen increases the magnification of the image. This is beneficial for observing the fine details of the grills and obtaining a sharper image.
2. Improved focusing: By moving the mirror towards the screen, the rays of light coming from the object are bent more strongly by the mirror and converge to form a focused image on the screen. This helps in obtaining a clear and sharp image of the grills.
3. Reduced aberrations: Moving the mirror closer to the screen helps to reduce aberrations such as spherical aberration and coma. These aberrations can cause blurring and distortions in the image, which can be minimized by proper adjustment of the mirror position.
Other options:
a) Moving the screen and the mirror away from the object: This would increase the distance between the mirror and the screen, resulting in a smaller image on the screen. It would not improve the focusing or magnification of the image.
b) Moving the screen and the mirror towards the object: This would decrease the distance between the mirror and the object, but it would not necessarily improve the quality of the image. It may result in a larger image on the screen, but the focusing and magnification would not be optimized.
d) Moving the screen slightly away from the mirror: This would increase the distance between the mirror and the screen, resulting in a smaller image on the screen. It would not improve the focusing or magnification of the image.
Therefore, option c) "Move the mirror slightly towards the screen" is the correct answer as it helps to improve the focusing, magnification, and overall quality of the image obtained using the concave mirror.
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