SAMPLE EXAM FOR CH's 22, 23,
24

**1]
**For
each part below, an object 25.0 cm
tall is located 40.0 cm in front of the mirror.

A)
For an image formed at q = +120 cm, **calculate**
the **height of the image **and **state**

whether it is **real or virtual **and whether it
is **erect or inverted**.

Answer: -75 cm,
real, inverted

B)
For an image formed at q = - 5.0 cm, **
calculate** the

and
**state** whether it is **concave or
convex**.

Answer: -11.4
cm
, convex

**2]
**Two
thin lenses, each with a focal length, f
= +20 cm, are placed 50 cm apart. An object

15
cm tall is placed 60 cm in front of the first lens.
Where is the final image formed for the
system?

Answer: No
image is formed, q would be at infinity.

5]
A screen is separated from a
double-slit source by a distance of 1.20 m.
The distance between

the slits is 0.030mm.
If light of
wavelength 633 nm is incident on
the slits, at what angle would you

find the **30th order** bright fringe?

Answer: 39.3
degrees

6] A
submarine is 300 m
horizontally out from the shore. It is 100 m below

the surface. A laser beam sent out from the sub strikes the
surface of the water

at a point 210 m from the shore. The beam exiting the water
strikes the top of a

tower standing right at the water's edge on the shore. Determine
the height of

the tower.

Answer: 107 m

MULTIPLE CHOICE

1) When total internal
reflection happens at a glass to air interface

a) half the light is refracted

b) half the light is reflected

c) light hits the interface from
the air side

d) light hits the interface from
the glass side

e) the law of reflection ceases
to hold

2) When you see your
image in a plane mirror, your image appears to be

a) in front of the mirror

b) at the surface of the mirror

c) behind the surface of the
mirror at a distance equal to your distance from the mirror

d) behind the surface of the
mirror at a distance equal to half your distance from the mirror

e) in front of the surface of the mirror at a distance equal to half your distance from the mirror

3) In a camera using a
simple lens, the image focused on the film would be

a) real and upright

b) real and inverted

c) virtual and upright

d) virtual and inverted

e) formed at infinity

4) A general condition
such that two waves will undergo destructive interference is

a) their phase difference is zero

b) their phase difference is +90
deg

c) their phase difference is + or
- 90 deg

d) their phase difference is an
even integral multiple of lambda/2 (wavelengths)

e) their phase difference is an
odd integral multiple of lambda/2 (wavelengths)

5) Increasing the wavelength in a double slit experiment
has what effect on the position of maxima on a screen

at a fixed distance?

a) maxima get closer together

b) maxima get farther apart

c) maxima get cancelled by minima

d) it has no effect

1. d

2. c

3. b

4. e

5. b