物理透鏡 DSE、CE 選擇題（第 3 頁）

21.

Questions 11 and 12 : An illuminated letter 'R' is placed in front of a lens as shown below and an image is formed on a translucent screen. The object distance is $30$ cm and the image distance is $20$ cm.

Illuminated letter R, lens and screen with object distance 30 cm and image distance 20 cm, and the observer's eye

If a piece of paper is used to cover one-half of the lens, which of the following describes the change in the image as seen by the observer ?

22.

If $F$ and $F'$ are the foci of the concave lens, which of the following ray diagrams is incorrect ?

Four ray diagrams A to D for a concave lens

23.

Object AB, its image A'B' and an optical device PQ with a ray from A passing through

In the above diagram, $A'B'$ is the image of an object $AB$ formed by an optical device $PQ$ . What is $PQ$ ?

24.

Object O and image I at the same point in front of a convex lens and a plane mirror; distances 10 cm and 4 cm

When an object $O$ is placed in front of a convex lens and a plane mirror as shown above, an image $I$ is formed at the same position as the object. Which of the following statements is/are correct ?

(1)The image

I

is real.

(2)The focal length of the lens is

10

cm.

(3)If the distance between the lens and the plane mirror is changed to

2

cm, the position of the image

I

would remain unchanged.

25.

A convex lens is used as a magnifying glass to read some small print in a book. The glass is placed $3$ cm from the book and the magnification is $3$ . What is the distance between the book and the image of the print ?

26.

Convex lens with foci F and F', incident ray AB and possible emergent rays P, Q, R and S

In the above diagram, $F$ , $F'$ are the foci of the convex lens and $AB$ is an incident ray. Which of the following paths best represents the emergent ray ?

27.

Which of the following statements concerning real images formed by a lens is/are correct ?

(1)Real images are always diminished.

(2)Real images can be photographed with a camera.

(3)Without a screen, real images cannot be seen by the eye.

28.

A lens is used to look at some print on a paper. The image of the word "PHYSICS" is shown above. Which of the following statements is/are correct ?

(1)The lens is a converging lens.

(2)The image lies between the paper and the lens.

(3)The image is real.

The words HKCE PHYSICS EXAM with the word PHYSICS seen through a hand-held lens

29.

Object O and its upright image I with points A, B, C and D on the axis

In the diagram, the image $I$ of an object $O$ is produced by a lens. What is the nature and position of this lens ?

30.

$Converging lens forming an image of an object, with refracted rays P, Q, S and T drawn$

In the figure above, $F$ is the focus of the converging lens. Which of the refracted rays is INCORRECTLY drawn ?