Lenses

Question 1

What is a convex lens?

Answer 1

A convex lens is thicker in the middle than it is at the edges.

Question 2

What happens to parallel light rays that enter a convex lens?

Answer 2

They converge at a point called the principal focus.

Question 3

What is the principal focus of a convex lens?

Answer 3

The point where parallel light rays converge.

Question 4

How is a convex lens represented in a ray diagram?

Answer 4

As a vertical line with outward facing arrows to indicate the shape.

Question 5

What is the focal length of a convex lens?

Answer 5

The distance from the lens to the principal focus.

Question 6

What is a concave lens?

Answer 6

A concave lens is thinner in the middle than at the edges.

Question 7

What happens to parallel rays when they pass through a concave lens?

Answer 7

They diverge and appear to come from a principle focus on the other side of the lens.

Question 8

How is a concave lens represented in a ray diagram?

Answer 8

A vertical line with inward facing arrows to indicate the shape of the lens.

Question 9

True or False: A concave lens causes parallel rays to converge.

Answer 9

False

Question 10

Fill in the blank: A concave lens causes parallel rays to _______.

Answer 10

diverge

Question 11

What types of images can be formed by a lens?

Answer 11

• Upright or inverted
• Magnified or diminished
• Real or virtual

These characteristics describe how the images relate to the original object.

Question 12

What is a real image?

Answer 12

An image that can be projected onto a screen

Real images are formed when light rays converge.

Question 13

What is a virtual image?

Answer 13

An image that appears to come from behind the lens

Virtual images cannot be projected onto a screen.

Question 14

What is the first step to draw a ray diagram?

Answer 14

Draw a ray from the object to the lens that is parallel to the principal axis

This ray will pass through the principal focus after passing through the lens.

Question 15

What is the second step to draw a ray diagram?

Answer 15

Draw a ray which passes from the object through the centre of the lens

This ray helps to determine the location of the image formed.

Question 16

What type of lenses do cameras and human eyes contain?

Answer 16

Convex lenses

Convex lenses are used to converge light rays.

Question 17

What is the nature of the image produced by a convex lens when an object is placed more than twice the focal length from the lens?

Answer 17

Inverted, diminished, real

This is a characteristic of image formation by convex lenses.

Question 18

What happens to the image when an object is placed between one and two focal lengths from a convex lens?

Answer 18

Inverted, magnified, real

This principle applies to projectors using convex lenses.

Question 19

Fill in the blank: For an object placed more than twice the focal length from a convex lens, the image is _______.

Answer 19

inverted, diminished, real

Question 20

Fill in the blank: For an object placed between one and two focal lengths from a convex lens, the image is _______.

Answer 20

inverted, magnified, real

Question 21

What is a magnifying glass?

Answer 21

A convex lens used to make an object appear much larger than it actually is.

Magnifying glasses utilize the properties of convex lenses to enlarge images.

Question 22

How does a magnifying glass work?

Answer 22

It works when the object is placed at a distance less than the focal length.

This positioning allows the lens to produce a magnified image.

Question 23

What are the characteristics of the image produced by a magnifying glass?

Answer 23

• Upright
• Magnified
• Virtual

These characteristics are essential for the functionality of a magnifying glass.

Question 24

What type of lens is used in peep holes?

Answer 24

Concave lenses

Concave lenses are used in peep holes to allow occupants to see visitors without opening the door.

Question 25

Fill in the blank: A magnifying glass is a _______ lens.

Answer 25

convex ## Footnote Convex lenses are known for their ability to converge light and magnify objects.

Question 26

What happens when an object is placed less than one focal length from a convex lens?

Answer 26

The image is upright, magnified, and virtual. ## Footnote This phenomenon is due to the behavior of light rays passing through the lens.

Question 27

What is a magnifying glass?

Answer 27

A convex lens used to make an object appear much larger than it actually is. ## Footnote Magnifying glasses utilize the properties of convex lenses to enlarge images.

Question 28

How does a magnifying glass work?

Answer 28

It works when the object is placed at a distance less than the focal length. ## Footnote This positioning allows the lens to produce a magnified image.

Question 29

What are the characteristics of the image produced by a magnifying glass?

Answer 29

* Upright * Magnified * Virtual ## Footnote These characteristics are essential for the functionality of a magnifying glass.

Question 30

What type of lens is used in peep holes?

Answer 30

Concave lenses ## Footnote Concave lenses are used in peep holes to allow occupants to see visitors without opening the door.

Question 31

Fill in the blank: A magnifying glass is a _______ lens.

Answer 31

convex ## Footnote Convex lenses are known for their ability to converge light and magnify objects.

Question 32

What happens when an object is placed less than one focal length from a convex lens?

Answer 32

The image is upright, magnified, and virtual. ## Footnote This phenomenon is due to the behavior of light rays passing through the lens.

Question 33

What type of lenses are used in peep holes?

Answer 33

Concave lenses ## Footnote Concave lenses allow occupants to identify visitors before opening the door.

Question 34

What is the effect of light rays from the top of an object viewed through a concave lens?

Answer 34

They will be refracted and will diverge on the other side of the lens ## Footnote This divergence creates a virtual image.

Question 35

What side of the principal axis does the image appear for an object viewed through a concave lens?

Answer 35

The same side ## Footnote This results in an upright image.

Question 36

How does the size of the image compare to the object when viewed through a concave lens?

Answer 36

The image will be smaller than the object ## Footnote This occurs because the rays appear closer to the principal axis.

Question 37

What is the principal axis in relation to a lens?

Answer 37

A line that passes through the center of the lens ## Footnote The principal axis is critical for ray diagrams.

Question 38

Fill in the blank: The focal length of a concave lens is _______.

Answer 38

negative ## Footnote Unlike convex lenses, concave lenses have a negative focal length.

Question 39

True or False: The image produced by a concave lens is always upright.

Answer 39

True ## Footnote The virtual image created by a concave lens is upright.