Junior Secondary · Science

Images formed by concave lenses : Practice Questions

5 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on Images formed by concave lenses .

10 questions28 marksFree, no account

Question 1

1 mark

If an object is placed at a distance of \(2F\) from a concave lens, where \(F\) is the focal length, how does the size of the image compare to the object?

Question 2

1 mark

Door viewers (security peepholes) often use concave lenses. Which property of the image formed by a concave lens makes it useful for this purpose?

Question 3

1 mark

A person with myopia (short-sightedness) uses spectacles with concave lenses. If this person removes their spectacles and looks at a distant object, which statement correctly describes the type of image formed by their eye's lens system on the retina?

Question 4

1 mark

Which of the following is a common characteristic of all images formed by a single concave lens when viewing a real object?

Question 5

1 mark

A convex lens and a concave lens both have the same numerical focal length of \(10\text{ cm}\). If an object is placed \(5\text{ cm}\) away from each lens, what is a common characteristic of the images formed by both lenses?

Question 6

2 marks

State the orientation and nature (real or virtual) of an image formed by a concave lens when a real object is placed in front of it.

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Question 7

4 marks

Between which two specific points on the principal axis is the image always located when a real object is placed at any distance in front of a concave lens?

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Question 8

5 marks

Explain how the diverging property of a concave lens makes it suitable for use in a security door viewer (peephole) to identify visitors.

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Question 9

4 marks

A student is investigating the properties of different lenses. He places an object very close to a lens, at a distance less than the focal length (\(u < f\)).

(a) If the lens is a concave lens, state the three main characteristics of the image formed.
(b) If the lens is a convex lens, state the three main characteristics of the image formed.
(c) State one similarity and one difference between the images formed by these two lenses in this specific setup.

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Question 10

8 marks

A student uses a concave lens to study the properties of light divergence. She places a small object of height 2 cm at various distances from the lens, which has a focal length of 10 cm.

(a) If the object is placed 15 cm from the optical centre, describe the nature, orientation, and relative size of the image formed. (3 points)
(b) The student then moves the object closer to the lens, to a distance of 5 cm. Will the image size increase, decrease, or stay the same compared to the image formed in part (a)? Justify your answer based on the movement of the image relative to the lens. (3 points)
(c) Explain why it is impossible for a single concave lens to create a magnified image of a real object, regardless of the object's position. (2 points)

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