Below are field lines for a magnetic field that lie in the plane of the picture,

Question

Below are field lines for a magnetic field that lie in the plane of the picture, along with a very long ("infinite") straight wire. Suppose the wire is held parallel to the plane of the picture, as shown. (Assume it extends well past the edges of the figure.)

Suppose the wire is moved toward the top of the page (UP).
(1) Would current through the wire flow to the left, to the right, or not at all?

(2) Which reasoning below correctly supports your conclusion?

(a) The velocity of the wire is in the same direction as the magnetic field so the magnetic force is zero.

(b) The velocity of the wire is in a direction that cuts across the magnetic field, so there is a non-zero force on the charges along the length of the wire.    

(c) Any time a wire moves in the presence of a magnetic field, there will be a current induced within the wire.

(d) The velocity of the wire and the magnetic field lie in different directions, so there is a non-zero force on the charges along the length of the wire.

(e) The velocity of the wire and the magnetic field both lie in the same plane, so the magnetic force on the charges in the wire is perpendicular to the plane of the picture.

Suppose instead that the wire were moved toward the left side of the page (LEFT).
(2) Would current through the wire flow to the left, to the right, or not at all?

(3) Which reasoning below correctly supports your conclusion?

(a) The velocity of the wire is in the same direction as the magnetic field so the magnetic force is zero.

(b) The velocity of the wire and the magnetic field lie in different directions, so there is a non-zero force on the charges along the length of the wire.    

(c) The velocity of the wire is in a direction that cuts across the magnetic field, so there is a non-zero force on the charges along the length of the wire.

(d) Any time a wire moves in the presence of a magnetic field, there will be a current induced within the wire.

(e) The velocity of the wire and the magnetic field both lie in the same plane, so the magnetic force on the charges in the wire is perpendicular to the plane of the picture.

Below are field lines for a magnetic field that lie in the plane of the picture, along with a very long (infinite) straight wire. Suppose the wire is held parallel to the plane of the picture, as shown. (Assume it extends well past the edges of the figure.) MFF_Q3_fig1 Suppose the wire is moved toward the top of the page (UP). (1) Would current through the wire flow to the left, to the right, or not at all? (2) Which reasoning below correctly supports your conclusion? (a) The velocity of the wire is in the same direction as the magnetic field so the magnetic force is zero. (b) The velocity of the wire is in a direction that cuts across the magnetic field, so there is a non-zero force on the charges along the length of the wire. (c) Any time a wire moves in the presence of a magnetic field, there will be a current induced within the wire. (d) The velocity of the wire and the magnetic field lie in different directions, so there is a non-zero force on the charges along the length of the wire. (e) The velocity of the wire and the magnetic field both lie in the same plane, so the magnetic force on the charges in the wire is perpendicular to the plane of the picture. Suppose instead that the wire were moved toward the left side of the page (LEFT). (2) Would current through the wire flow to the left, to the right, or not at all? (3) Which reasoning below correctly supports your conclusion? (a) The velocity of the wire is in the same direction as the magnetic field so the magnetic force is zero. (b) The velocity of the wire and the magnetic field lie in different directions, so there is a non-zero force on the charges along the length of the wire. (c) The velocity of the wire is in a direction that cuts across the magnetic field, so there is a non-zero force on the charges along the length of the wire. (d) Any time a wire moves in the presence of a magnetic field, there will be a current induced within the wire. (e) The velocity of the wire and the magnetic field both lie in the same plane, so the magnetic force on the charges in the wire is perpendicular to the plane of the picture.

Explanation / Answer

1)

Here , For moving the wire upeards ,

as the field is in plane of wire ,

change in flux will be zero

and hence ,

No Current flows through the wire.

2)

Here , the correct reasoning is

(e) The velocity of the wire and the magnetic field both lie in the same plane, so the magnetic force on the charges in the wire is perpendicular to the plane of the picture.

For moving the wire to the left

2)

In this case also , NO current will flow.

3)
(e) The velocity of the wire and the magnetic field both lie in the same plane, so the magnetic force on the charges in the wire is perpendicular to the plane of the picture.

Related Questions

Navigate

• Browse (All)
• Browse B
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.