The endoscope, using lenses, the eye Flashcards Preview

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Flashcards in The endoscope, using lenses, the eye Deck (21)
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0

The refractive index of water is 1.33. Calculate the critical angle of water.

1
Refractive index = ------
sin c

Where C = the critical angle

1

Complete the statements with these words:
Refraction, reflection, partial reflection and total internal reflection

1: When a light ray travels from air to glass and changes direction, it undergoes ________

2: When a light ray inside glass reaches the surface with air and stays in the glass, it undergoes ________

3: When a light ray passes from glass to air, some of the light undergoes ________

4: When a light ray inside glass reaches the surface with air, it undergoes ________ and ________ if the angle of incidence is less than the critical angle.

1: Refraction
2: Reflection
3: Partial reflection
4: Refraction and Total internal reflection

2

When does total internal reflection occur?

When the angle of incidence of a light ray in a transparent substance is greater than the critical angle.

3

What is an endoscope used for?

An endoscope is used to see inside the body directly.

4

Complete the statements with the following words:
Converging, diverging, real and virtual

1: A ________ lens can be used to focus light from an object on to a screen. The image of the object is a ________ image.

2: A ________ lens can be used to make light rays from a point object spread out more. The image of the object is a ________ image.

1: Convex, real
2: Concave, virtual

5

A postage stamp is inspected using a converging lens as a magnifying glass. Describe the image.

Magnified, upright, virtual

6

A converging lens is used to form a magnified image of a slide on a screen. Describe the image formed.

Real, inverted, magnified

7

What does a converging (Convex) lens do?

Focuses parallel rays to a point called the principal focus.

8

What does a diverging (Concave) lens do?

Makes parallel waves appear as if they have come from the principal focus.

9

When is a real image formed with lenses?

It is formed by a convex lens if the object is further away than the principal focus.

10

When is a virtual image formed by lenses?

It is formed by a concave lens at all times, and with a convex lens when the object is further away than the principal focus.

11

What is the equation used to calculate magnification?

Image height
Magnification= -------------------
Object height

12

Why is a ray diagram drawn?

To find the position and nature of an image formed by a lens

13

In a ray diagram, if an object is placed between a converging lens and its principal focus, what kind of image is formed?

Virtual, upright, magnified and on the same side of the lens as the object.

14

What are two uses of converging lenses?

In cameras where they are used to form a real image of an object

In magnifying glasses where they are used to form a virtual image of an object

15

Complete the statements with these words:
Lens, iris, cornea, retina

1: The front of the eye is protected by the ________
2: The pupil of the eye is at the centre of the ________
3: The ________ of the eye focuses light onto the ________

1: Cornea
2: Iris
3: Lens, retina

16

What is the range of vision of a normal human eye?

25cm to infinity

17

What is the equation for calculating the power of a lens?

1
P = ---------------------------------
Focal length in meters

18

What is short-sightedness and how is it corrected?

A short-sighted eye is one that can only see near objects clearly. This is corrected using a diverging lens.

19

What is short-sightedness and how is it corrected?

A long-sighted eye is one that can only see distant objects clearly. This is corrected using a converging lens.

20

What qualities does a spectacle lens with a higher refractive index have?

The higher the refractive index, and flatter and thinner the lens can be.