Chapter 12: Light

Question 1

What are the characteristics of a mirror image?

Answer 1

The mirror image:
* is upright (or erect)
* is laterally inverted (reversed left ot right)
* is virtual, not real
* (image) size = object size
* (image) distance from the mirror = object distance from the mirror

Question 2

What is Snell’s law?

Answer 2

Snell’s law states that for a given pair of media, the ratio of the sines of the angles in the media is equal to the ratio of the refractive indices of the two media.

Question 3

State the relationship between the density of a medium, and the direction of a light ray (during the light ray’s transferrence of medium)

Answer 3

• When a light ray travels from an optically less dense (or rarer) medium to an optically denser medium, the ray bends towards the normal.
• When a ligh ray travels from an optically denser medium, the raye bends away from the normal.

Question 4

How do you calculate the reflective index?

Answer 4

Question 5

Other than n = c/v, using the concept of depth of water, how can you calculate the refractive index

Answer 5

n = real depth / apparent depth

Question 6

Explain what a critical angle is

Answer 6

• When the angle of refraction is 90°, the angle of incidence is known as the critical angle

Question 7

What are the conditions for total internal reflection?

Answer 7

Conditions for total internal reflection:
* Light must travel from an opticallly denser medium to an optically less dense medium
* The angle of incidence inside the optically denser medium must be greater than the critical angle.

Question 8

How do you calculate a critical angle?

Answer 8

Question 9

What are the characteristics of the image if the object is at infinity?

Answer 9

• Image is real, inverted and diminisbed.
• Image is formed on the other side of the lens at F

Uses: Telescope

Question 10

What are the characteristics of an image when the object is placed further than 2F?

Answer 10

• Image is real, inverted and diminished.
• Image is formed on the other side of the lens between F and 2F

Question 11

What are the characteristics of the image of an object placed at 2F?

Answer 11

• Image is real, inverted and same size
• Image is formed on the other side of the lens with distance greater than 2F

Question 12

What are the characteristics of an image when the object is placed in between of F and 2F?

Answer 12

• Image is real, inverted and magnified.
• Image is formed on the other side of the lens with distance greater than 2F

Question 13

What are the characteristics of an image when an object placed at F?

Answer 13

• No image is formed

Question 14

What are the characteristics of the image when an object is placed between F and C?

Answer 14

• Image is virtual, upright and magnified.
• Image is formed on the same of the lens at the back of the object