Download Clicker question 26-1

Clicker question 26-­1
Electrons travel at an initial v elocity v 0. They pass through a s et of deflection plates, between which there exists an electric field which deflects them upwards toward point b. In which direction s hould a magnetic field be applied so that the electrons land undeflected at a?
Clicker Question 27-­1
A horizontal wire carries a current and is in a vertical magnetic field. What is the direction of the force on the wire?
a)
b)
c)
d)
e)
Right
Left
Into the page
Out of the page
None of the above I
B
Clicker Question 27-­2
A vertical wire carries a current and is in a vertical magnetic field. What is the direction of the force on the wire?
a)
b)
c)
d)
e)
Right
Left
Into the page
Out of the page
None of the above I
B
Clicker Question 27-­3
A rectangular current loop on the xy-­plane is in a uniform magnetic field in the z -­
direction. The c urrent is flowing in c ounterclockwise on the loop as s hown. What is the direction of the net force on the loop? a)
b)
+ x
+ y
c)
The net force is zero.
d)
e)
-­ x
-­ y
z
x
y
B
Clicker Question 27-­4
If there is a current in the loop in the direction shown, the loop will:
a)
b)
c)
d)
e)
move up
move down
rotate clockwise
rotate counterclockwise
both rotate and move
N
S
Clicker question 28-­1
Two wires lying in the plane of this page carry equal currents in opposite directions, as shown. At a point midway between the wires, the magnetic field is
a)
b)
c)
d)
e)
zero. into the page. out of the page. in the direction of the red arrow
in the direction of the blue arrow
Clicker question 28-­2
The figure shows four circular Amperian loops concentric with a wire whose current is directed out of the page. The current is uniform across the wire’s circular cross s ection. Rank the loops according to the magnitude of around each.
∑ B! ΔL
a)
b)
c)
d)
e)
a > b > c > d
a = b = c = d
a = b > c > d
a = b > c = d
a > b > c = d
a
b
c
d
Clicker question 28-­3
Two wires lying in the plane of this page carry c urrents in opposite directions, as shown. Do these wires exert force on each other?
a)
b)
c)
d)
e)
No.
Yes. They are attracted to each other.
Yes. They repel each other.
Yes. The bottom wire will repel the top wire, but the top wire will attract the bottom wire.
Yes. The top wire will repel the bottom wire, but the bottom wire will attract the top wire.
Clicker Question 29-­1
Find the direction of the induced current in the conducting loop shown if the magnet is moving to the left (away from the loop).
a) Clockwise.
b) Counterclockwise. c) No current is induced.
Clicker Question 29-­2
Wire #1 (length L) forms a one-­turn loop, and a bar magnet is dropped through. Wire #2 (length 2L) forms a two-­turn loop of the same s ize. The wires are made of the s ame c onductor and have the s ame diameter. The same magnet is dropped through both wires. Compare the magnitude of the induced currents in these two c ases.
a)
b)
c)
d)
I1
I1
I1
I1
> I2
< I2
= I2 ≠ 0
= I2 = 0
S
S
N
N
Clicker Question 29-­3
A wire loop is being pulled to the right through a uniform magnetic field that points into the page and suddenly ends. What is the direction of the induced current at the instance shown?
a)
b)
c)
Clockwise
Counterclockwise
No induced current x x x x x x x x x x x x x x x
x x x x x
x x x x x
v
Clicker Question 30-­1
A conductor (shaded) is moving to the right in an external magnetic field directed into the x x x x x page. Which direction do free electrons in the conductor feel force?
x x x x x a) Up
b)
c)
d)
e)
Down
Out of the page
Into the page
Actually, there is no force acting on the free electrons.
x x x x x
x x x x x
x x x x x
v
Clicker Question 30-­2
A conducting rod (blue) slides on a conducting track in a constant B field directed into the page. What is the direction of the induced current?
a) Clockwise
b) Counterclockwise
c) No induced current x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x v
Clicker Question 30-­3
A conducting rod (blue) slides on a conducting track in a constant B field directed into the page. What direction is the magnetic force on the rod as it moves?
a)
b)
c)
d)
e)
To the left
To the right
Up
Down
No magnetic force
x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x v
Clicker Question 30-­4
Two identical bar magnets are dropped from equal heights. Magnet A is dropped inside a wooden tube and magnet B dropped inside an aluminum (not magnetic) tube. Which magnet strikes the ground first?
a) magnet A b) magnet B c) both strike at the same time