Midterm I

Question 1

Electric and magnetic fields are “in phase” which means that

Answer 1

they each are zero at the same points and reach their maxima at the same points in space

Question 2

very far from the antenna the filed lines are quite flat over a reasonably large area and the waves are referred to as

Answer 2

plane waves

Question 3

B and E are perpendicular to each other and to the direct of travel OR

Answer 3

direction of wave velocity

Question 4

EM are – waves because the amplitude is perpendicular to the direction of wave travel

Answer 4

transverse

Question 5

EM waves are always aves of – not of matter so they can propagate in empty space

Answer 5

fields

Question 6

– electric charges gives rise to EM waves

Answer 6

accelerating

Question 7

free space

Answer 7

no charges or conduction currents

Question 8

speed of EM waves in empty space =

Answer 8

speed of light

Question 9

The net magnetic flux through a closed surface is

Answer 9

zero

Question 10

Gauss’s law for magnetism concludes that isolated magnetic poles

Answer 10

do not exist

Question 11

An electric field is produced by a

Answer 11

changing magnetic field

Question 12

A changing electric field will produce a

Answer 12

magnetic field

Question 13

Electromagnetic waves are

Answer 13

transverse

Question 14

Far from their source, EM waves are

Answer 14

plane waves

Question 15

In the radiation field from an antenna, the E and B fields are – to one another

Answer 15

perpendicular

Question 16

Right hand rule for the direction of propagation of the EM waves

Answer 16

point fingers of your right hand toward the E vector, curl your fingers towards the B vector, and the thumb will point the direction of propagation

Question 17

If an EM wave has it magnetic field oscillating in the vertical direction, the direction of oscillation of the electric field is

Answer 17

horizontal

Question 18

If the magnetic field in an EM wave is in the x-direction and the electric field in the wave is in the y-direction so the wave is traveling in the

Answer 18

negative z direction

Question 19

An EM wave is propagating towards the west. At a certain moment the direction of the magnetic field vector points vertically up. What is the direction of the electric field vector?
(Horizontal or vertical, pointing south or down or north or up or east)

Answer 19

horizontal and south

Question 20

An EM wave propagates along the + y direction. If the E-field at the origin is along the +z direction what is the direction of the B-field?

Answer 20

+ x direction

Question 21

E vector is in the +z direction, the B vector is the the +x direction what is the direction of propagation of the EM wave?

Answer 21

+ y direction

Question 22

Shortest wavelength: microwaves, IR, gamma rays, x-rays, UV

Answer 22

gamma rays

Question 23

Order from low to high frequencies: radio waves, IR, Microwaves, UV, visible, x-rays, gamma rays

Answer 23

radio waves, microwaves, IR, visible, UV, x-rays, gamma rays

Question 24

the energy per unit volume in an EM wave is – divided between E and B fields

Answer 24

equally

Question 25

the force per unit area exerted by an EM wave is called

Answer 25

radiation pressure

Question 26

-- objects receives a larger amount of momentum

Answer 26

reflecting

Question 27

an AM radio station indicates its location on the dial as 1030 --

Answer 27

kHz

Question 28

Reflection, refraction, and the formation of images by mirrors and lenses has been successfully described by the

Answer 28

ray model of light

Question 29

The angle of incidence must -- the angle of reflection

Answer 29

equal

Question 30

Describe the imaged formed by a plane mirror.

Answer 30

virtual and upright

Question 31

plane mirrors produce images which are always --

Answer 31

the same size as the actual object

Question 32

an image formed by a plane mirror is at a -- the distance behind the mirror as the object is in front of the mirror

Answer 32

same

Question 33

An image formed when the light rays do not actually pass through the image location and would not appear on paper or film placed at that location is called

Answer 33

virtual image

Question 34

an image formed when the light rays pass through the image location and could appear on paper or film at that location is called

Answer 34

real image

Question 35

Is it possible to see a virtual image?

Answer 35

Yes, the rays that appear to emanate from a virtual image can be focuses on the retina just like those from an illuminated object

Question 36

A light ray is reflected by two mirrors that are perpendicular. The new direction of the ray is -- from the original direction

Answer 36

180 degrees

Question 37

How tall must a plane mirror be in order for you to be able to see your full image in it?

Answer 37

half your height

Question 38

A concave mirror has a -- focal length

Answer 38

positive

Question 39

A convex mirror has a -- focal length

Answer 39

negative

Question 40

To find an image by ray tracing requires -- rays

Answer 40

two

Question 41

A beam of light that is parallel to the principal axis is incident on a concave mirror. What happens to the reflected beam of light?

Answer 41

It passes through the focal point of the mirror

Question 42

A beam of light is parallel to the principal axis is incident on a convex mirror. What happens to the reflected beam of light?

Answer 42

It appears to be coming from the focal point on the other side of the mirror

Question 43

A light ray, traveling obliquely to a concave mirror's axis, crosses the axis at the mirror's center of curvature before striking the mirror's surface. After reflection, this ray passes through the mirror's --

Answer 43

center of curvature

Question 44

A light ray, traveling obliquely to a concave mirror's surface, crosses the axis at the mirror's focal point before striking the mirror's surface. After reflection, this ray travels -- to the mirror's axis

Answer 44

parallel

Question 45

If the image distance is positive, the image formed by a mirror is

Answer 45

real

Question 46

If the image distance is negative, the image formed by a mirror is

Answer 46

virtual

Question 47

If the absolute value of the magnification is larger than one, then the image is -- than the object

Answer 47

larger

Question 48

If the absolute value of the magnification is smaller than one, then the image is -- than the object

Answer 48

smaller

Question 49

when you stand in front of a concave mirror, exactly at its focal point

Answer 49

you won't see your image because there is none

Question 50

if you stand in front of a convex mirror, at the same distance from it as the radius of curvature

Answer 50

you will see your image and you will appear smaller

Question 51

if you stand in front of a convex mirror at the same distance from it as its focal length

Answer 51

you will see your image and you will appear smaller

Question 52

an object placed in front of a convex mirror at a distance larger than twice the focal length of the mirror will have an image that

Answer 52

is upright and reduced

Question 53

concave spherical mirrors produce images which

Answer 53

could be smaller, larger, or the same size

Question 54

convex spherical mirrors produce images which

Answer 54

are always smaller than the actual object

Question 55

A single concave spherical mirror produces an image which is real only if the object distance is

Answer 55

greater than f

Question 56

A single convex spherical mirror produces an image which is (V or R)

Answer 56

always virtual

Question 57

If the magnification of a mirror is negative, then the image is

Answer 57

inverted and the mirror is concave

Question 58

For all transparent materials, the index of refraction is -- to 1

Answer 58

greater than

Question 59

An index of refraction < 1 for a medium would imply that the speed of light in the medium is -- than the speed of light in a vacuum

Answer 59

greater than

Question 60

An index of refraction of diamond is 2.42. This means that a given frequency of light travels 2.42 times faster in --

Answer 60

vacuum than it does in diamond

Question 61

When light enters a material of higher index of refraction, its speed

Answer 61

decreases

Question 62

The angle of incidence is -- the angle of refraction

Answer 62

may be >, <, or equal to

Question 63

Light traveling at an angle into a denser medium is refracted -- the normal

Answer 63

toward

Question 64

Light enters air from water. The angle of refraction will be -- the angle of incidence

Answer 64

greater than

Question 65

A ray of light, which is traveling in air, is incident on a glass plate at a 45 degree angle. The angle of refraction in the glass is -- than 45 degrees

Answer 65

less than

Question 66

A beam of light in air is incident on a glass slab at an angle of incidence < 90 degrees. After entering the glass slab, the beam of light bends -- to the normal drawn at the point of contact

Answer 66

towards

Question 67

At a quiet pond with crystal clear water, you decide to fish with bow and arrow. When you aim at the fish you see, you must aim

Answer 67

deeper than you perceive the fish to be

Question 68

The spreading of white light into its spectrum is called

Answer 68

dispersion

Question 69

When light passes through a prism the color refracted most is

Answer 69

violet

Question 70

Which color of light undergoes the smallest refraction when passing from air to glass?

Answer 70

red

Question 71

When sill the critical angle exist?

Answer 71

n1 > n2