Q. No.A concave mirror of focal length \(10~\text{cm}\) forms an image which is double the size of object when the object is placed at two different positions. The distance between the two positions of the object is: (in cm)
1. \(50\)
2. \(30\)
3. \(10\)
4. \(40\)
1. \(50\)
2. \(30\)
3. \(10\)
4. \(40\)
Subtopic: Reflection at Spherical Surface |
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A rod of length \(10~\text{cm}\) lies along the principle axis of a concave mirror of focal length \(10~\text{cm}\) as shown in figure. The length of the image is: (in cm)
1. \(2.5\)
2. \(5\)
3. \(7.5\)
4. \(7\)
1. \(2.5\)
2. \(5\)
3. \(7.5\)
4. \(7\)
Subtopic: Reflection at Spherical Surface |
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In parallax method for the determination of focal length of a concave mirror, the object should always be placed:
| 1. | between the focus (\(F\)) and the centre of curvature (\(C\)) of the mirror ONLY |
| 2. | at any point beyond the focus (\(F\)) of the mirror |
| 3. | beyond the centre of the curvature (\(C\)) of the mirror ONLY |
| 4. | between the pole (\(P\)) and the focus (\(F\)) of the concave mirror ONLY |
Subtopic: Reflection at Spherical Surface |
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Distance between an object and three times magnified real image is \(40 ~\text{cm}.\) The focal length of the mirror used is: (in \(\text{cm}\))
1. \(-\dfrac{15}{2}\)
2. \(– 10\)
3. \(– 20\)
4. \( – 15\)
1. \(-\dfrac{15}{2}\)
2. \(– 10\)
3. \(– 20\)
4. \( – 15\)
Subtopic: Reflection at Spherical Surface |
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A finite size object is placed normal to the principal axis at a distance of \(30 ~\text{cm}\) from a convex mirror of focal length \(30 ~\text{cm}.\) A plane mirror is now placed in such a way that the image produced by both the mirrors coincide with each other. The distance between the two mirrors is:
1. \(7.5 ~\text{cm}\)
2. \(22.5 ~\text{cm}\)
3. \(45 ~\text{cm}\)
4. \(15 ~\text{cm}\)
1. \(7.5 ~\text{cm}\)
2. \(22.5 ~\text{cm}\)
3. \(45 ~\text{cm}\)
4. \(15 ~\text{cm}\)
Subtopic: Reflection at Spherical Surface |
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Distance between object and its image (magnified by \(-1/3 \)) is \(30 ~\text{cm.}\) The focal length of the mirror used is \((x/4) ~\text{cm,}\) then the magnitude of value of \(x\) is:
1. \(26\)
2. \(45 \)
3. \(17 \)
3. \(40\)
1. \(26\)
2. \(45 \)
3. \(17 \)
3. \(40\)
Subtopic: Reflection at Spherical Surface |
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When an object is placed \(40 ~\text{cm}\) away from a spherical mirror an image of magnification \(\dfrac{1}{2}\) is produced. To obtain an image with magnification of \(\dfrac{1}{3}\) the object is to be moved:
| 1. | \(20 ~\text{cm}\) away from the mirror. |
| 2. | \(40 ~\text{cm}\) away from the mirror. |
| 3. | \(80 ~\text{cm}\) away from the mirror. |
| 4. | \(20 ~\text{cm}\) towards the mirror. |
Subtopic: Reflection at Spherical Surface |
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A mirror is used to produce an image with magnification of \(\dfrac{1}{4}.\) If the distance between object and its image is \(40~\text{cm,}\) then the focal length of the mirror is:
1. \(10.7~\text{cm}\)
2. \(15~\text{cm}\)
3. \(12.7~\text{cm}\)
4. \(10~\text{cm}\)
1. \(10.7~\text{cm}\)
2. \(15~\text{cm}\)
3. \(12.7~\text{cm}\)
4. \(10~\text{cm}\)
Subtopic: Reflection at Spherical Surface |
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Two identical objects are placed in front of convex mirror and concave mirror having same radii of curvature of \(12 ~\text{cm,}\) at same distance of \(18 ~\text{cm}\) from the respective mirrors. The ratio of sizes of the images formed by convex mirror and by concave mirror is:
1. \(2\)
2. \(\dfrac{1}{2} \)
3. \(\dfrac{1}{3} \)
4. \(3\)
1. \(2\)
2. \(\dfrac{1}{2} \)
3. \(\dfrac{1}{3} \)
4. \(3\)
Subtopic: Reflection at Spherical Surface |
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A concave mirror produces an image of an object such that the distance between the object and image is \(20 ~\text{cm.}\) If the magnification of the image is \(-3,\) then the magnitude of the radius of curvature of the mirror is:
1. \(7.5~\text m\)
2. \(30~\text {cm}\)
3. \(3.75~\text{cm}\)
4. \(15~\text{cm}\)
1. \(7.5~\text m\)
2. \(30~\text {cm}\)
3. \(3.75~\text{cm}\)
4. \(15~\text{cm}\)
Subtopic: Reflection at Spherical Surface |
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