Science: Lenses and Mirrors Worksheet

Question 1

Define reflection and refraction in the context of light.

Accepted Answer

Reflection is the bouncing of light off a surface. Refraction is the bending of light as it passes from one medium into another because its speed changes.

Question 2

State the law of reflection.

Accepted Answer

The law of reflection states that the angle of incidence is equal to the angle of reflection, measured from the normal to the surface.

Question 3

Describe the difference between a plane mirror, a concave mirror, and a convex mirror.

Accepted Answer

A plane mirror has a flat surface and forms an upright virtual image. A concave mirror curves inward and can form either real or virtual images depending on the object's position. A convex mirror curves outward and forms upright, reduced virtual images.

Question 4

A light ray strikes a flat mirror with an angle of incidence of 35 degrees. What is the angle of reflection?

Accepted Answer

The angle of reflection is 35 degrees because the angle of incidence equals the angle of reflection.

Question 5

Explain what the focal point of a converging lens is.

Accepted Answer

The focal point of a converging lens is the point where parallel light rays meet after passing through the lens.

Question 6

Compare a converging lens and a diverging lens.

Accepted Answer

A converging lens bends parallel light rays inward so they move toward a focal point. A diverging lens bends parallel light rays outward so they spread apart as if they came from a focal point behind the lens.

Question 7

A concave mirror has a focal length of 12 cm. An object is placed 36 cm in front of the mirror. Use the mirror equation to find the image distance.

Accepted Answer

Using 1/f = 1/do + 1/di, substitute f = 12 cm and do = 36 cm. Then 1/12 = 1/36 + 1/di. So 1/di = 1/12 - 1/36 = 2/36 = 1/18. The image distance is 18 cm.

Question 8

A converging lens has a focal length of 10 cm. An object is placed 30 cm from the lens. Use the lens equation to find the image distance.

Accepted Answer

Using 1/f = 1/do + 1/di, substitute f = 10 cm and do = 30 cm. Then 1/10 = 1/30 + 1/di. So 1/di = 1/10 - 1/30 = 2/30 = 1/15. The image distance is 15 cm.

Question 9

What does it mean for an image to be virtual?

Accepted Answer

A virtual image is formed when light rays only appear to come from a location but do not actually meet there. A virtual image cannot be projected onto a screen.

Question 10

What does it mean for an image to be real?

Accepted Answer

A real image is formed when light rays actually converge at a point. A real image can be projected onto a screen.

Question 11

A convex mirror always forms what kind of image? Describe its orientation and size.

Accepted Answer

A convex mirror always forms a virtual image that is upright and smaller than the object.

Question 12

An object is placed between a converging lens and its focal point. Describe the image formed.

Accepted Answer

When an object is placed between a converging lens and its focal point, the lens forms a virtual, upright, and enlarged image on the same side of the lens as the object.

Question 13

Why does a straw appear bent when it is partly submerged in water?

Accepted Answer

The straw appears bent because light from the submerged part refracts as it moves from water into air. This bending changes the apparent position of that part of the straw.

Question 14

A concave mirror produces an enlarged upright image of an object. Where is the object located relative to the focal point?

Accepted Answer

The object is located between the mirror and the focal point. In this position, a concave mirror forms a virtual, upright, and enlarged image.

Question 15

Give one everyday use of a concave mirror and one everyday use of a convex mirror. Explain why each mirror is useful.

Accepted Answer

A concave mirror is used in makeup or shaving mirrors because it can produce an enlarged upright image when the face is close to the mirror. A convex mirror is used in vehicle side mirrors or security mirrors because it gives a wider field of view.

Science: Lenses and Mirrors

Science: Lenses and Mirrors

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