A biconvex lens \((\mu=1.5)\)  has a radius of curvature of magnitude \(20~\text{cm}\). Which one of the following options, best describes, the image formed by an object of height \(2\) cm placed \(30~\text{cm}\) from the lens?
1. virtual, upright, height \(=0.5\) cm
2. real, inverted, height \(=4\) cm
3. real, inverted, height \(=1\) cm
4. virtual, upright, height \(=1\) cm
Subtopic:  Lenses | Lens Makers' Formula | Refraction at Curved Surface |
 70%
From NCERT
AIPMT - 2011
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A converging beam of rays is incident on a diverging lens. Having passed through the lens the rays intersect at a point \(15~\text{cm}\) from the lens on the opposite side. If the lens is removed the point where the rays meet will move \(5~\text{cm}\) closer to the lens. The focal length of the lens is:
1.  \(5~\text{cm}\)
2. \(-10~\text{cm}\)
3. \(20~\text{cm}\)
4. \(-30~\text{cm}\)

Subtopic:  Lenses |
 53%
From NCERT
AIPMT - 2011
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A lens having focal length \(f\) and aperture of diameter \(d\) forms an image of intensity \(I\). An aperture of diameter \(\frac{d}{2}\) in central region of lens is covered by a black paper. The focal length of lens and intensity of the image now will be respectively:
1. \(f\) and \(\frac{I}{4}\)
2. \(\frac{3f}{4}\) and \(\frac{I}{2}\)
3. \(f\) and \(\frac{3I}{4}\)
4. \(\frac{f}{2}\) and \(\frac{I}{2}\)

Subtopic:  Lenses |
 57%
From NCERT
AIPMT - 2010
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Two thin lenses of focal lengths f1 and f2 are in contact and coaxial. The power of the combination is:

1. f1f2

2. f2f1

3. f1+f2f1f2

4. None of the above

Subtopic:  Lenses |
 87%
From NCERT
AIPMT - 2008
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A boy is trying to start a fire by focusing sunlight on a piece of paper using an equiconvex lens of a focal length of \(10\) cm. The diameter of the sun is \(1.39\times10^9\) m and its mean distance from the earth is \(1.5\times10^{11}\) m. What is the diameter of the sun's image on the paper?
 

1. \(9.2\times10^{-4}\) m 2. \(6.5\times10^{-4}\) m
3. \(6.5\times10^{-5}\) m 4. \(12.4\times10^{-4}\) m
Subtopic:  Lenses |
 58%
From NCERT
AIPMT - 2008
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A convex lens and a concave lens, each having the same focal length of 25 cm, are put in contact to form a combination of lenses. The power in dioptres of the combination is:

1. 25

2. 50

3. infinite

4. zero

Subtopic:  Lenses |
 59%
From NCERT
AIPMT - 2006
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