Review Game

Review Activity : GP2

Multiple Choice

Which of these choices could possibly show a correct representation of the field lines?

• a

• b

• c

• d

Answer: Option C

Recall that electric field lines begin on positive charges and end on negative charges. The tangent to a field line at a point gives the direction of the electric field at that point. Equally spaced parallel field lines indicate that the field has a constant value (magnitude and direction) in the corresponding region of space.

Open Ended

Why is option A incorrect?

Why is this incorrect?

Field lines can never cross. If two field lines were to intersect, there would be two electric fields at the point of intersection, one associated with each line. However, there can only be one value of the electric field at a given point. 

Open Ended

Why is option B incorrect?

Why is this incorrect?

The number of field lines that leave a positive charge or end on a negative charge is proportional to the magnitude of the charge. Since 8 lines leave the +4q charge, one-half of them (or 4) must end on the -2q charge, and one-fourth of them (or 2) must end on each of the -q charges.  

Open Ended

Why is option D incorrect?

Why is this incorrect?

the field lines between the +4q charge and the -2q charge are parallel and evenly spaced, which would indicate that the field everywhere in this region has a constant magnitude and direction. 

Multiple Select

Is the electric force is a conservative force?

• Yes

• Sometimes

• No

Multiple Choice

TRUE or FALSE:

For a negative charge, it has the greatest potential energy at the center of the plate.

• TRUE

• FALSE

Multiple Choice

All metals show strong magnetic effects.

• TRUE

• FALSE

Ferromagnetic

includes iron, a few other materials, such as cobalt, nickel, gadolinium, and some of their oxides and alloys, show strong magnetic effects 

Magnetic field as a navigation tool

Vertebrates and some invertebrates (like this lobster /crustacean) use the earth’s magnetic field to navigate and can determine its geographic location.

This ability may be related to the presence in the lobsters of the mineral magnetite, a magnetic material used for compass needles. 

Multiple Choice

What is the direction of the force magnetic force if the magnetic field is directed upward and the charge moves towards the negative y-axis?

• west

• into the page/screen

• east

• none

• all of the above

No force?

Recall that the requirements for a magnetic force to exist are the following: 1)The charge must be moving, because no magnetic force acts on a stationary charge.

The velocity of the moving charge must have a component that is perpendicular to

the direction of the magnetic field.