Chapter 09 Light – Reflection and Refraction Questions-01
Questions
1. Define the principal focus of a concave mirror.
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Answer
Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror. This point is known as the principal focus of the concave mirror.
2. The radius of curvature of a spherical mirror is 20 cm. What is its focal length?
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Answer
Radius of curvature, $R=20 cm$
Radius of curvature of a spherical mirror $=2 \times$ Focal length ( $f$ )
$R=2 f$
$f=\dfrac{R}{2}=\dfrac{20}{2}=10 cm$
Hence, the focal length of the given spherical mirror is $10 cm$.
3. Name a mirror that can give an erect and enlarged image of an object.
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Answer
When an object is placed between the pole and the principal focus of a concave mirror, the image formed is virtual, erect, and enlarged.
4. Why do we prefer a convex mirror as a rear-view mirror in vehicles?
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Answer
Convex mirrors give a virtual, erect, and diminished image of the objects placed in front of them. They are preferred as a rear-view mirror in vehicles because they give a wider field of view, which allows the driver to see most of the traffic behind him.
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