Two wires are parallel to each other and carry the same current in the same direction

i) there is no force between the wires

ii) both wires are attracted to each other

iii) both wires are repelled by each other

iv) one wire is attracted and the other wire is repelled

At a given instant, electromagnetic waves are traveling vertically up. The E-vector is oriented toward the south and horizontal. The direction of the B-vector at this instant is to the

i) north

ii) south

iii) west

iv) east

The distance of the image of an object in a plane mirror, to the mirror

i) may be larger than the distance of the object to the mirror

ii) may be smaller than the distance of the object to the mirror

iii) is always equal to the distance of the object to the mirror

iv) one cannot decide without knowing whether the image is real or virtual.

iii) is always equal to the distance of the object to the mirror

di=do

The plane of a rectangular loop is parallel to the magnetic field. The magnitude of the magnetic field is decreasing.

i) there is no induced current on the loop

ii) the induced current in the loop flows counter-clockwise

iii) the induced current in the loop flows clockwise.

iv) the direction of the induced current cannot be determined.

i) there is no induced current in the loop

Φ=BA cos 90

Φ=O Tm²

The electric field vector of an electromagnetic wave is expressed as (in the metric system of units: Ē=2.0ÿcos(ωt+kz)

i) the electric field vector is oscillating the in the ± z-direction

ii) the magnetic field vector is oscillating in the ± y-direction

iii) the electromagnetic waves are traveling the the + z-direction

iv) the electromagnetic waves are traveling in the - z-direction

Your cell phone uses a 3.6 volt battery. It can be recharged using a DC-power supply that can be plugged into the electric outlet at the wall (120 volts.) The transformer inside the recharger

i) has more turns in its primary than its secondary

ii) has less turns in its primary than its secondary

iii) has the same number of turns in its primary as its secondary

iv) no statement can be made concering the number of turns in the primary or the secondary

i) has more turns in its primary than its secondary

Vs = Ns    3.6 Np=120 Ns

Vp   Np                          

      3.6    = Ns

      120       Np

A beam made of a mixture of molecular hydrogen ions (H₂⁺_, molecular mass = 2amu) and doubly ionized Helium ions (He⁺⁺, atomic mass = 4amu) enters a magnetic mass spectrometer as the same speed. The radius of the semi-circular trajectory for He⁺⁺ ions is R. The radius of the semi-circular trajectory of the H₂⁺ ions is r. (Of course, the radius is related to other quantities by applying Newton's second law to the magnetic force.) In this situation we can assert that

i) R=r

ii) R>r

iii) R<r

iv) R is not related to r

i) R=r

H₂⁺       He⁺⁺      F=ma=mv²= qvBsinθ

   r             R                         r                  

2amu        4amu            mV=qB               

q=e        q=2e              r                      

r=2v/eB     R=4V/23B          r=mv                  

re=v        2eR=v              qb           

   2   B           4    B                                  

re = 2eR         r=R

  2       4                  

At a given instant, electromagnetic waves are traveling vertically down. The E-vector is oriented toward the east and horizontal. The direction of the B-vector at this instant is horizontal and points to the

i) north

ii) south

iii) west

iv) east

the image of an object in a plane mirror

i) is always virtual

ii) is always real

iii) may be real or virtual depending on its position

iv) may be real or virtual depending on its direction (up or down)

At a power plant a transformer increases the line voltage from 200 Volts to 100,000 Volts. This transformer

i) has more turns in its primary than its secondary

ii) has less turns in its primary than its secondary

iii) has the same number of turns in its primary as its secondary

iv) No statement can be made concerning the number of turns in the primary or the secondary

ii) has less turns in its primary than its secondary

200=primary     100,000=secondary

Vs = Ns

Vp  Np

100,000 = Ns

    200       Np

Ns=1,000

Np=2

For a right handed coordinate reference system xyz, the electric field vector of an electromagnetic wave is expressed as (in the metric system of units): Ē=2.0ȳ(ωt-kz)

i) the electric field vector is oscillating in the ±x direction

ii) the magnetic field vector is oscillating in the ±x direction

iii) the magnetic field vector is oscillating in the ±y direction

iv) the electromagnetic waves are traveling in the -z direction

ii) the magnetic field vector is oscillating in the ±x direction

+2 prop

+yE

±xB

A ray passes through the focal point of a concave mirror and hits the mirror. Which of the following statement is valid for the reflected ray?

i) the reflected ray passes throguh the center of curvature

ii) the reflected ray is parallel to the principle axis

iii) the relected ray passes through the focal point

iv) the reflected ray is normal to the surface of the mirror

At a given instant, electromagnetic waves are traveling vertically down. The B-vector is oriented toward the north and horizontal. The direction of the E-vector at this instant is horizontal and points to the

i) north

ii) south

iii) west

iv) east

The image of an object from a concave mirror

i) is always virtual

ii) is always real

iii) may be real or virtual depending on its position

iv) is always upright

iii) may be real or virtual depeding on its position

-convex is always virtual

-concave is real or virtual

For a right handed coordinate reference system xyz, the magnetic field vector of an electromagnetic wave is expressed as (in the metric system of units): B=2.0ȳcos(ωt-kz). This equation implies that

i) the electromagnetic waves are traveling in the +y direction

ii) the electromagnetic waves are traveling in the +x direction

iii) the magnetic field vector is oscillating in the ±x direction

iv) the electric field vector is oscillating in the ±x direction

iv) the electric field vector is oscillating in the ± x direction

B=±y

prop= -z

E perp B

At a power plant a transformer increases the line voltage from 200 volts to 100,000 volts. This transformer

i) the current in its primary is larger than the current in its secondary.

ii) the current in its primary is smaller than the current in its secondary.

iii) the current in its primary is the same as the current in its secondary.

iv) no statement can be made concering the currents in the primary or the secondary.

i) the current in its primary is larger than the current in its secondary.

P=200

S=100,000

P/S

Two wires are perpendicular to each other and carry the same current. Point P is closer to the horizontal wire. The direction of the total magnetic field at P is

i) into the paper

ii) out of the paper

iii) parallel to the horizontal wire

iv) parallel to the vertical wire

There is a current flowing in the single loop and the magnet is stationary. The ring as shown in the figure is repelled by the magnet but is clamped to its position. As you look into the North pole of the magnet,

i) the current in the loop is flowing clockwise

ii) the current in the loop is flowing counterclockwise

iii) the direction of the current in the ring is determined by the direction of the induced current

iv) the direction of the current cannot be determined if the magnet is not moving

A step-down transformer reduces the input voltage. In this case

i) the number of turns in the primary is less than the number of turns in the secondary

ii) the number of turns in the primary is larger in the number of turns in the secondary

iii) the number of turns in the primary is the same as the number of turns in the secondary

iv) no statement can be made about the relation between the number of the turns in the primary and the secondary

ii) the number of turns in the primary is larger than the number of turns in the secondary

Vp=Np  1° ↑V

Vs  Ns          

2° ↓V

An object is placed in front of a concave spherical mirror as shown. The three rays 1, 2, and 3, leave the top of the object and, after reflection, converge at a point on the top of the image. Ray 1 is parallel to the principal axis, ray 2 passes through F, and ray 3 passes through C. Which ray(s) will reflect back parallel to the principal axis?

i) 1 only

ii) 2 only

iii) 3 only

iv) 1, 2, and 3

As a bean of monochromatic red light from a laser is transmitted from air into water

i) both its speed and frequency changes

ii) both its wavelength and speed changes

iii) both its wavelength and frequency changes.

iv) since the light is monochromatic, nothing changes

A converging lens of 25 cm of focal length is glued to a diverging lens of 10 cm of focal length without any air gap between the lenses

i) the combined sytstem forms a diverging lens

ii) the combined system forms a converging lens

iii) one needs to know the indices of refractions to decide

iv) one needs to know indices of refractions and the radii of curvatures of the lenses to decide

i) the combined systems forms a diverging lens

1/f= 1/25-1/10

f=-16.67

Two wires are parallel to each other and carry the same current in the same direction

i) there is no force between the wires

ii) both wires are attracted to each other

iii) both wires are repelled by each other

iv) one wire is attracted and the other wire is repelled

a long, straight wire is in the same plane as a rectangular, conducting loop. The wire carries a constant current I as shown in the figure. Which one of the following statements is true if the wire is suddenly moved toward the loop?

i) there will be no induced emf and no induced current

ii) there will be an induced emf, but no induced current

iii) there will be an induced current that is clockwise around the loop

iv) there will be an induced current that is counterclockwise around the loop

Complete the following sentence: The various colors of visible light differ in

i) frequency

ii) frequency and wavelength

iii) wavelength only

iv) their speeds in a vacuum

Which one of the following phrases most accurately describes paraxial rays?

i) rays that pass throught the principal focus

ii) rays that come to a focus on the principal axis

iii) rays close to the principal axis and parallel to it

iv) rays close to the principal axis, but not necessarily parallel to it

An object is placed in front of a concave spherical mirror as shown. The three rays 1, 2, and 3, leave the top of the object and, after reflection, converge at a point on the top of the image. Ray 1 is parallel to the principal axis, ray 2 passes through F, and ray 3 passes through C. Which ray(s) will reflect back on itself (themselves)?

i) 1 only

ii) 2 only

iii) 3 only

iv) 1,2, and 3

A physics student desires to create a beam of light that consists of parallel rays. Which one of the following arrangements would allow her to accomplish this task?

i) a point light source placed at the focal point of a convex mirror

ii) a point light source placed at the focal point of a converging lens

iii) a point light source placed at the focal length of a diverging lens

iv) none of the above

A convergent lens of 5 cm of focal length is glued to a divergent lens of 10 cm of focal length without any air gap between the lenses. The focal length of the combined system is:

i) 15 cm

ii) 5 cm

iii) 3.33 cm

iv) 10 cm

For a right handed xyz coordinate system the instantaneous E-vector is in the -y direction, and direction of propagation of the electromagnetic waves is in the +z direction. In the case, the direction of the instantaneous B-vector is in

i) +x direction

ii) -x direction

iii) +z direction

iv) -z direction

The net magnetic field at some point of space is constant and points horizontally in the North direction. the current in a wire flows at this point in a horizontal direction from west towards the east. In that case, the direction of the magnetic force exerted on the wire is

i) horizontal and pointing south

ii) horizontal and pointing north

iii) vertical and pointing down

iv) vertical and pointing up

A convergent lens with a very small focal length is place in contact (no gap) with a very large focal length convergent lens. The combined focal length is,

i) much larger than either

ii) approximately equal to the smaller

iii) approximately equal to the larger

iv) none of these

An infinitely long wire and a single loop are on top of a table. The plane of the loop is parallel to the plane of the table. The loop is moving with constant speed v parallel to the wire.

i) there will be no induced current in the loop

ii) as seen from above, the induced current is running clockwise

iii) as seen from above, the induced current is running counterclockwise

iv) none of the above, we need to know the direction of the current in the wire

An electron moving in the positive y direction, at right angles to a magnetic field, expereinces a magnetic force in the negative x direction. What is the direction of the magnetic field?

i) it is in the negative x direction

ii) it is in the positive y direction

iii) it is in the negative z direction

iv) it is in the positive z direction

For a right handed xyz coordinate system, if the E-vector is in the +z direction, and the B-vector is in the +x direction, what is the direction of propagation of the electromagnetic waves?

i)+x

ii)-x

iii)+y

iv)+z

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

i) closer to the surface then you perceive the fish to be

ii) directly at the fish

iii) deeper than you perceive the fish to be

iv) it depends on how deep the pond is

which of the following sets of characteristics descrives the image formed by a plane mirror?

i) real and inverted

ii) real and upright

iii) virtual and upright

iv) virtual and inverted

The net magnetic field at some point of space is constant and points horizontally in the West direction. The current in a wire flows at this point in a horizontal direction from south toward the north. in that case, the direction of the magnetic force exerted on the wire is

i) horizontal and pointing east

ii) horizontal and pointing west

iii) vertical and pointing down

iv) vertical and pointing up

As a vertical bar moves horizontally on two rails in a constant magnetic field, we observe that the voltage at point A is higher than the voltage at point B. We conclude that the direction of the constant magnetic field is

i) in the plane of the paper, towards the right

ii) in the plane of the paper, towards the left

iii) perpendicular to the plane of the paper and into it

iv) perpendicular to the plane of the paper and out of it

A point light-source emits light isotropically (the same in all directions) We measure the intensity of the light at a distance r from the source to be I. we move our measurement device to a distance of r/2. At this point we measure an intensity which is

i) 4I

ii) 2I

iii) I/2

iv) I/4

i) 4I

I∂ 1/r²

I= 1   

      (1/r)²

I= 1/4

In the figure above you are looking at the South pole of the permanent magnet. There is an attractive force between the permanent magnet and the stationary ring shown. When your eye is placed at this spot you observe that

i) the current in the ring flows counterclockwise

ii) the current in the ring flows clockwise

iii) we cannot decide about in what direction is the current flowing in the ring

iv) there cannot be a current in the ring

At a given instant the electric field vector is in the vertical up direction and the magnetic field is pointing toward east direction. The electromagnetic wave is propagating toward

i)the south

ii)the north

iii)the west

iv)none of the above

Charged negative ions after passing through a velocity selector enter a mass spectrometer and follow the trajectory 1 shown in the figure. There is no magnetic field in region A and there is a constant magnetic field in region B. Which one of the following statements is correct?

i) the magnetic field in region B is perpendicular to the page and out the page

ii) the magnetic field in region B is perpendicular to the page and into the page

iii) the magnetic field in region B is in the plane of the paper and toward your right

iv) the magnetic field in region B is in the plane of the paper and toward your left

A wire is placed between the north and south poles of a magnet as shown. The magnetic force on the wire is perpendicular to the plane of the page and is out of the page. the direction of the current in the wire is

i) from the top of the page to the bottom of the page

ii) from the bottom of the page to the top of the page

iii) parallel to the magnetic field

iv) no statement can be made about the direction of the current

A step-down transformer reduces the input voltage. In this case

i) the current in the primary is the same as the current in the secondary since no charge can be created or destroyed

ii) the current in the primary is more than the current in the secondary

iii) the current in the primary is less than the current in the secondary

iv) no statement can be made about the relation between the currents in the primary and the secondary

At a given instant the electric field vector is in the veritcal up direction and the electromagnetic wave is propagating toward the east. At this instant, the magnetic field is pointing toward

i) the south

ii) the north

iii) the west

iv) none of the above

A permanent magnet is made of a

i) paramagnetic material

ii) ferromagnetic material

iii) diamagnetic material

iv) all of the above

At a given instant the electric field vector is pointing to the east and the electromagnetic wave is propagating toward the north. At this instant, the magnetic field is pointing

i) up

ii) down

iii) toward the south

iv) toward west

Protons of speed v enter the region between the poles of a magnet as shown in the figure and are deflected. Which one of the following statements is correct?

i) the top magnet pole is a north pole

ii) the top magnet pole is a south pole

iii) both the top and the bottom poles are north poles

iv) both the top and the bottom poles are south poles

An external magnetic field is pointing out of the plane of a circular loop and decreasing. The induced current flows

i) counterclockwise (CCW) in the circular loop

ii) clockwise in the circular loop

iii) no current is induced in the loop

iv) first flows clockwise, then counterclockwise

There is a current flowing in the single loop. Both the magnet and the loop are clamped in their positions and are stationary. The loop as shown in the figure is attracted the magnet but cannot move. As you look into the North pole of the magnet,

i) the direction of the curent of the loop is determined by the direction of the induced current

ii) the direction of the current cannot be determined if the magnet is not moving

iii) as you look into the north pole of the magnet you see that the current in the loop is flowing counterclockwise

iv) as you look into the north pole of the magnet you see that the current in the loop is flowing clockwise

A step-up transformer increases the input voltage. In this case

i) the output current is the same as the input current since no charge can be created or destroyed

ii) the output current is larger than the input current

iii) the output current is smaller than the input current

iv) no statement can be made about the reltion between the currents in the primary and the secondary. We can only make statements about the input and output voltages.

Only one of the processes below does not induce an electric current in a conducting loop.

i) expanding the area of the loop

ii) increasing the magniture of a magnetic field perpendicular to the surface of the loop

iii) decreasing the magniture of a magnetic field perpendicular to the surface of the loop

iv) moving the loop parallel to a uniform magnetic field

To start a fire by reflecting sun rays from a mirror one should use

i) a convex mirror

ii) a concave mirror

iii) a plane mirror

iv) one cannot start a fire using a mirror