Lenses

Question 1

What is a lens?

Answer 1

Shaped piece of transparent glass or plastic that reflects light

Question 2

What happens when light is refracted?

Answer 2

It changes direction due to the change in density as it moves from air to glass or plastic

Question 3

Where are lenses used?

Answer 3

Cameras
Telescopes
Binoculars
Microscopes
Corrective glasses

Question 4

What does a concave lens look like?

Answer 4

Thinner in the middle then the edges

Question 5

What do light rays do in convex lenses?

Answer 5

Parallel light rays enter the lens and converge
They come together at a point called the principle focus

Question 6

How are convex lenses drawn in ray diagrams?

Answer 6

They are drawn as a vertical line with outwards facing arrows to indicate shape of the lens

Question 7

What is focal length ?

Answer 7

Distance from lens to principle focus

Question 8

What do concave lenses look like?

Answer 8

Thinner in the middle than the edges

Question 9

What happens to light rays in a concave lens?

Answer 9

Parallel rays diverge
They separate but appear to come from behind a principle focus on the other side of the lens

Question 10

How are concave lenses drawn in ray diagrams?

Answer 10

It’s drawn as a vertical line with inwards facing arrows to indicate shape of the lens

Question 11

What can images formed by a lens be?

Answer 11

Upright or inverted
Magnified or diminished
Real or virtual

Question 12

What is a real image?

Answer 12

Image that can be projected onto a screen

Question 13

What is a virtual image?

Answer 13

Image appears to come from behind the lens

Question 14

What are light rays in virtual images like?

Answer 14

Rays of light appear to come but do not so in reality

Question 15

What devices contain convex lenses?

Answer 15

Cameras and eyes

Question 16

What does the image formed by a convex lens depend on?

Answer 16

Lens used
Distance from object to lens

Question 17

What type of image is formed when the object is placed far from the lens?

Answer 17

Inverted
Diminished
Real

Question 18

How must film be loaded into a projector?

Answer 18

Upside down so the projected image is the right way up

Question 19

How do convex lenses make an object appear larger than it actually is?

Answer 19

Object is placed at a distance less than the focal length

Question 20

What is the image of magnifying glasses like:

Answer 20

Upright
Magnified
Virtual

Question 21

Why can’t a magnifying glass be projected onto a screen?

Answer 21

Because it is a virtual image

Question 22

What happens to light rays in concave lenses in peep holes?

Answer 22

They will be referacted and diverge on the other side of the lens

Question 23

How do concave light rays appear?

Answer 23

From the same side as the principle axis so the image will be upright
Further from the principle axis so the image will be smaller than the object

Question 24

What image do concave lenses produce?

Answer 24

Upright
Diminished
Virtual

Question 25

What is the order of visible light frequency

Answer 25

Red Orange Yellow Green Blue Indigo Violet

Question 26

Where can waves be absorbed?

Answer 26

At the boundary between two different materials

Question 27

What happens when waves are absorbed by a surface?

Answer 27

The energy of the waves is transferred to the particles in the surface This increases the internal energy of the particles

Question 28

What happens when white light is shined on an opaque object?

Answer 28

Some of the wavelength or colours are absorbed and not detected by our eyes Other wavelengths are reflected and detected by our eyes

Question 29

How does grass appear green?

Answer 29

Red,orange,yellow,blue,indigo,violet are absorbed the the grass Green is reflected by the grass and detected by our eyes

Question 30

Where can waves be transmitted?

Answer 30

At the boundary between two different materials

Question 31

Why do waves continue transmitting through air,glass and water?

Answer 31

Because they are good at transmitting light They are transmitted with very little absorption

Question 32

What are translucent materials

Answer 32

Materials that transmit some light but not completely clear

Question 33

What are examples of translucent objects?

Answer 33

Lamp shades Shower curtains Window blinds

Question 34

What happens when light passes through a colour filter?

Answer 34

All colours are absorbed except the colour of the filter

Question 35

What makes an object appear black?

Answer 35

If the object absorbs all of the wavelength of visible light

Question 36

What happens to a blue object placed in red lighting?

Answer 36

It appears black because there is no blue light to reflect