Lenses and the Eye

The focal length of a converging (convex) lens is equal to
A converging lens forms a virtual image of a real object when the object is
1. inside the focus.
2. at the focus.
3. between the centre of curvature and the focus.
4. at the centre of curvature.
5. outside the centre of curvature.
Which one of the following statements is incorrect?
A converging lens may form an image which is
1. real, inverted and magnified.
2. real, inverted and diminished.
3. real, erect and diminished.
4. virtual, erect and magnified.
5. real, inverted and same size as object.
An object is placed at a distance of 2f from a converging lens of focal length f.
The magnification of the image is
1. 1
2. 1/2
3. 2
4. 3/2
When an object is placed outside the focal point of a converging lens, the image
1. is always real and inverted.
2. is always virtual and erect.
3. may be real and erect
4. is always magnified and virtual.
The focal length of a converging lens is equal to
1. half the radius of curvature.
2. quarter the radius of curvature.
3. the radius of curvature.
4. twice the radius of curvature.
The image formed by a diverging lens is always
1. virtual, upright and diminished.
2. virtual, upright and magnified.
3. virtual, inverted and diminished.
4. real, upright and diminished.
5. real, upright and magnified.
A diverging lens is arranged between a ray box and a screen as shown.
An image of the lamp box will not be formed on the screen because
1. the image is virtual.
2. the image is diminished.
3. the distance between the ray box and the screen is too small.
4. the screen is inside the focus of the lens.
5. the ray box is inside the focus of the lens.
An object is placed at a distance of f from a diverging lens of focal length f.
The magnification of the image is
1. ½
2. 2
3. ⅓
4. 1
5. ⅔
A converging lens is focussed to give an image on a screen 5 m from the lens when the slide is 10 cm behind the lens.
If the slide is 2 cm x 2 cm, the size of the image on the screen will be
1. 100 cm × 100 cm
2. 20 cm × 20 cm
3. 80 cm × 80 cm
4. 50 cm × 50 cm
5. 200 cm × 200 cm
The image formed by a diverging lens is
1. virtual, inverted and diminished if the object is outside the focus.
2. always virtual, erect and magnified.
3. virtual, erect and magnified if the object is inside the focus.
4. always virtual, inverted and diminished.
5. always virtual, erect and diminished.
An illuminated object is placed at a distance of 15 cm from a convex lens of focal length 10 cm.
The image obtained on a screen is
1. inverted and magnified.
2. upright and magnified.
3. upright and same size.
4. inverted and diminished.
5. upright and diminished.
The diagram shows a converging (convex) lens.
Identify the parts labelled X and Y in the diagram.
1. X = centre of curvature, Y = focal length
2. X = focus, Y = focal length
3. X = centre of curvature, Y = focus
4. X = radius of curvature, Y = principal axis
A converging lens of focal length 12 cm is combined with a diverging lens of focal length 18 cm.
The focal length of the combination is
1. 36 cm
2. 36/5 cm
3. 30 cm
4. 6 cm
5. 24 cm
When an object is placed inside the principal focus of a converging lens, the image formed is
1. virtual, upright and magnified.
2. virtual, inverted and magnified.
3. virtual, upright and diminished.
4. real, upright and magnified.
which of the following statements is correct with respect to the eye?
1. A person who is short-sighted needs to wear convex lenses to correct the defect.
2. The image is always formed on the retina.
3. The pupil varies the size of the iris.
4. A long-sighted person does not see distant objects clearly.
5. Refraction of light does not take place at the cornea.
The human eye can focus objects close to it by
1. making the eye lens thicker.
2. making the eye lens thinner.
3. increasing the distance between the eye and lens.
4. decreasing the distance between the eye and lens.
5. Increasing the size of the pupil.
In the human eye, the image is formed on
1. the retina
2. the lens
3. the cornea
4. the optic nerve
5. the iris
The image formed in the eye is
1. real, inverted and diminished.
2. virtual, inverted and magnified.
3. virtual, erect and diminished.
4. real, erect and diminished.
5. real, inverted and magnified.
The power of a convex lens of focal point 15 cm is
1. 1/15
2. 15
3. 30
4. 0.15
Two lenses of focal lengths 10 cm and 20 cm respectively are in contact with each other. If both lenses are convex, what is the combined power of the two lenses in contact?
1. 15 m^-1
2. 0.15 m^-1
3. 0.3 m^-1
4. 20/3 m^-1
When drawing ray diagrams, which one of the following is incorrect?
An object is placed at the centre of curvature of a convex lens.
Its image will be
1. the same size and inverted.
2. the same size and upright.
3. the same size and virtual.
4. diminished and real.
5. magnified and real.
An object is placed 25 cm in front of a convex mirror whose focal length is 15 cm.
What will be the magnification of its image?
1. 3
2. ⅓
3. 60/7
4. 3/7
Identify the parts of the eye labelled A and B in the diagram.
1. A = retina, B = lens
2. A = retina, B = cornea
3. A = optic nerve, B = lens
4. A = iris, B = retina
Identify the parts of the eye labelled X and Y in the diagram.
1. X = optic nerve, Y = ciliary muscle
2. X = retina, Y = ciliary muscle
3. X = optic nerve, Y = lens
4. X = cornea, Y = ciliary muscle
Clear watery fluid found between the cornea and the lens.
1. Aqueous humour
2. Vitreous humour
3. Ciliary muscle
4. Optic nerve
Identify the parts of the eye labelled P and Q in the diagram.
1. P = iris, Q = cornea
2. P = iris, Q = retina
3. P = cornea, Q = pupil
4. P = retina, Q = cornea
The diagram shows rays entering a human eye.
This diagram represents
1. a normal eye
2. hyperopia
3. myopia
4. a black eye
The diagram shows rays entering a human eye.
This diagram represents
1. long-sightedness
2. short-sightedness
3. a normal eye
4. astigmatism
The diagram shows rays entering a human eye.
This diagram represents
1. myopia
2. hyperopia
3. a normal eye
4. conjuctivitis
Which one of the following diagrams represents myopia being corrected by a lens?

Lenses and the Eye

Multiple Choice Quiz