ch 19

Question 1

when the object distance is greater than the focal point, what type of image is created for a converging mirror? what is the sign of s’? what is the sign of f?

Answer 1

an inverted, real image on the same side as the object. s’ is positive, f is positive

Question 2

when the object distance is greater than the focal point, what type of image is created for a converging lens? what is the sign of s’? what is the sign of f?

Answer 2

a real inverted image and s’ is positive on the opposite side of the lens, f is positive.

Question 3

when the object distance is less than the focal point for a converging lens, what type of image is created? what is the sign of s’, what is the sign of f?

Answer 3

a virtual upright image on the same side of the object, s’ is negative, f is positive

Question 4

when the object distance is less than the focal point for a converging mirror, what type of image is created? what is the sign of s’, what is the sign of f?

Answer 4

a virtual upright image on the opposite side of the mirror, s’ is negative, f is positive

Question 5

what type of image is made with a diverging lens? what is the sign of f? what side is the image on? what is the sign of s’

Answer 5

an upright virtual image on the same side of the object, s’ is negative, f is negative

Question 6

what type of image is made with a diverging mirror? what is the sign of f? what side is the image on? what is the sign of s’

Answer 6

a virtual upright image on the opposite side of the mirror, s’ is negative, f is negative

Question 7

how does the eye focus

Answer 7

changing its focal length

Question 8

what does low refractive power mean

Answer 8

it bends the rays at a smaller angle to produce a long focal length

Question 9

what does high refractive power mean

Answer 9

it bends the rays at a larger angle to produce a shorter focal length

Question 10

what is total refractive power

Answer 10

it is the sum of the refractive power of two lenses

Question 11

what type of lens has positive refractive power

Answer 11

converging

Question 12

what type of lens has negative refractive power

Answer 12

diverging

Question 13

what is the far point for an eye

Answer 13

it is the furthest point a relaxed eye can see, the focal length is longest at this point and the angle is small

Question 14

what is the near point for an eye

Answer 14

it is the nearest point a cotnracted eye can see, the focal length is the shortest at this point and the angle is large

Question 15

what is hyperopia, what is the solution

Answer 15

it is farsightedness, the eye can see far but their near point is further than 25 cm and objects within that range are blurry

the solution is a converging lens that increases the refractive power and decreases the focal length

Question 16

what is myopia, what is the solution

Answer 16

it is when the far point is not far and distant objects converge too soon in front of the retina

the solution is a diverging lens that decreases the refractive power and increases the focal length

Question 17

why do objects appear larger than they are

Answer 17

when objects are closer they have a larger angular size

Question 18

how do magnifiers work

Answer 18

we place an object at the near point of the converging lens and this creates a far virtual image

Question 19

what does the magnification depend on in a telescope

Answer 19

the eye piece only

Question 20

what is white light

Answer 20

balanced mixture of colors

Question 21

what is dispersion and what does it depend on

Answer 21

dispersion is the slight variation of the index of refraction with wavelength

the index of refraction is higher with shorter wavelengths so violet would refract more than red

Question 22

how do opaque objects appear colored

Answer 22

they absorb light from some wavelengths but reflect light of other wavelengths

Question 23

what is resolution and aberrations

Answer 23

resolution is the ability to make out fine details, aberrations are lens imperfections

Question 24

what are spherical aberrations

Answer 24

they are the inability of a spherical lens to focus on a single point

Question 25

what are chromatic aberrations

Answer 25

caused by dispersion where different wavelengths focyus at different points

Question 26

Why do better “triplet” magnifiers (loupes) use multiple lenses?

Answer 26

to reduce aberrations