In case of a concave mirror, if an object is kept between principal focus F and pole P of the mirror, then which one of the following statements about the image is NOT correct?
- A.The image will be virtual
- B.The image will be enlarged or magnified
- C.The image will be formed at infinity
- D.The image will be erect
Correct answer
Explanation
The correct answer is C, The image will be formed at infinity. For an object between F and P, the image forms behind the mirror, not at infinity.
When an object is placed between the pole and the principal focus of a concave mirror, the reflected rays spread out and never meet in front of the mirror. When extended backwards they appear to meet behind it, so the image is virtual, erect and larger than the object. This is why a concave mirror is used as a shaving mirror and by dentists. The image is formed at infinity only when the object is placed exactly at the focus F.
A is correct: the rays only appear to meet, so the image is virtual. B is correct: the image is enlarged. D is correct: a virtual image formed by a mirror is erect.
Exam tip: Concave mirror, object at F gives image at infinity; object between F and P gives a virtual, erect, enlarged image behind the mirror.
Practice Questions
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- B.Martin Luther
- C.Johannes Kepler
- D.Copernicus
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In 1609 Kepler showed that the planets move around the Sun in elliptical orbits, with the Sun at one focus of the ellipse.
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- B.Objective lens-Condenser-Body tube-Eyepiece
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- D.Eyepiece-Objective lens-Body tube-Mirror
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- B.Histones are proteins that are present in nucleus in association with DNA.
- C.Histones are proteins associated with lipids in the cytosol.
- D.Histones are proteins associated with carbohydrates in the cytosol.
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