It has been observed that a mirror always forms the image between the pole and the focus, irrespective of the location of the object. Which one of the following is correct in respect of the nature of the mirror?
- A.It is a plane mirror.
- B.It is a convex mirror.
- C.It is a concave mirror of small focal length.
- D.It is a concave mirror of large focal length.
Correct answer
Explanation
The correct answer is B, It is a convex mirror. For any real object, a convex mirror forms a virtual, erect and smaller image behind the mirror, between the pole and the focus.
A convex mirror bulges outward and spreads light rays apart. As the object moves from far away towards the mirror, the image moves from the focus towards the pole but never leaves that stretch. Because the image is always upright and diminished, a convex mirror shows a wide field of view, which is why it is used as a rear-view mirror in vehicles and at blind turns on hill roads.
A is wrong because a plane mirror forms the image as far behind it as the object is in front, not within a focal length.
C and D are wrong because a concave mirror forms images at many places, from between the pole and focus to beyond the centre of curvature, depending on where the object is, whatever its focal length.
Exam tip: convex mirror = always virtual, erect, diminished, between P and F; rear-view mirrors use it.
Practice Questions
View allRecently, there was a growing awareness in our country about the importance of Himalayan nettle (Girardinia diversifolia) because it is found to be a sustainable source of
- A.anti-malarial drug
- B.biodiesel
- C.pulp for paper industry
- D.textile fibre
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The Himalayan nettle yields a strong natural fibre that can be spun and woven into cloth. Girardinia diversifolia, known as Himalayan giant nettle or allo, is a stinging shrub that grows wild in the moist forests of the Himalayas, including Uttarakhand, Himachal Pradesh and the North-east, as well as Nepal.
Read the full explanation →Which of the following statements are correct regarding the general difference between plant and animal cells ? 1. Plant cells have cellulose cell walls whilst animal cells do not. 2. Plant cells do not have plasma membrane unlike animal cells which do. 3. Mature plant cell has one large vacuole whilst animal cell has many small vacuoles. Select the correct answer using the code given below:
- A.1 and 2 only
- B.2 and 3 only
- C.1 and 3 only
- D.1,2 and 3
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Plant cells have a cellulose wall and one large central vacuole, but they do have a plasma membrane, just like animal cells.
Read the full explanation →Consider the following statements : 1. In tropical regions, Zika virus disease is transmitted by the same mosquito that transmits dengue. 2. Sexual transmission of Zika virus disease is possible. Which of the statements given above is/are correct ?
- A.1 only
- B.2 only
- C.Both 1 and 2
- D.Neither 1 nor 2
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- A.1 only
- B.1 and 2 only
- C.3 only
- D.1, 2 and 3
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Read the full explanation →Which one of the following is NOT true for bleaching powder?
- A.It is used as a reducing agent in chemical industries
- B.It is used for bleaching wood pulp in paper factories
- C.It is used for disinfecting drinking water
- D.It is used for bleaching linen in textile industry
Show answer
Bleaching powder is an oxidising agent, not a reducing agent, so this statement is the false one. Bleaching powder, calcium oxychloride (CaOCl₂), is made by passing chlorine gas over dry slaked lime, Ca(OH)₂.
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