To determine focal length of a concave mirror a student obtains the im...
The distance between mirror and the screen will give the focal length of the mirror as the mirror focuses the light on the screen.
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To determine focal length of a concave mirror a student obtains the im...
To determine the focal length of a concave mirror, a student can use the method of obtaining the image of a well-lit distant object on a screen. In this method, the distance between the mirror and the screen is required to determine the focal length.
Explanation:
1. Concave Mirror:
A concave mirror is a curved mirror where the reflective surface is on the inner side of the curve. It is also known as a converging mirror because it converges the incident light rays to a point called the focal point.
2. Focal Length:
The focal length of a concave mirror is the distance between the mirror and its focal point. It is denoted by the symbol 'f'. The focal length determines the amount of convergence or divergence of light rays by the mirror.
3. Method to Determine Focal Length:
To determine the focal length of a concave mirror, the student can follow these steps:
a) Place the concave mirror on a stand.
b) Position a well-lit distant object in front of the mirror.
c) Adjust the position of the screen until a clear and sharp image of the object is formed on the screen.
d) Measure the distance between the mirror and the screen. This distance is the focal length of the concave mirror.
4. Reasoning behind the Correct Answer:
The correct answer is option 'C' - the distance between the mirror and the screen. This is because the focal length of a concave mirror can be determined by measuring the distance between the mirror and the screen when a clear image of a well-lit distant object is formed on the screen.
5. Importance of the Distance between the Mirror and the Object:
The distance between the mirror and the object is not required to determine the focal length of a concave mirror in this method. The object distance affects the size and position of the image formed, but it does not directly determine the focal length.
In conclusion, to determine the focal length of a concave mirror, a student needs to measure the distance between the mirror and the screen when a clear image of a well-lit distant object is formed on the screen. This method allows for an accurate determination of the focal length, which is an important parameter of a concave mirror.
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