Ch.210.5 Flashcards
- A long, straight wire carries a current I. If the magnetic field at a distance d from the wire has
magnitude B, what is the magnitude of the magnetic field at a distance 2d from the wire?
A) ----- B/2 B) B/4 C) 2B D) 4B E) 8B
- An overhead electric power line carries a maximum current of 125 A. What is the magnitude of the
maximum magnetic field at a point 4.50 m directly below the power line?
A) ----- 5.56 × 10–6 T B) 1.75 × 10–5 T C) 3.49 × 10–5 T D) 4.69 × 10–4 T E) 7.95 × 10–3 T
It’s a power line, and 556 is my phone number
- A coil of wire carries current I as shown in the figure. If the observer could “see” the magnetic field
inside this arrangement of loops, how would it appear?
The diagram with the X’s
- A wire, connected to a battery and switch, passes through the center of a long current-carrying
solenoid as shown in the drawing.
When the switch is closed and there is a current in the wire, what happens to the portion of the wire that
runs inside of the solenoid?
A) —– There is no effect on the wire.
B) The wire is pushed downward.
C) The wire is pushed upward.
D) The wire is pushed into the plane of the paper.
E) The wire is pushed out of the plane of the paper.
- Two loops carry equal currents I in the same direction. The loops are held in the positions shown in
the figure and are then released. Which one of the following statements correctly describes the
subsequent behavior of the loops?
A) Both loops move to the left.
B) The loops remain in the positions shown.
C) The top loop moves to the right; the bottom loop moves to the right.
D) The loops repel each other.
E) —– The loops attract each other.
- Four long, straight wires are parallel to each other; and their cross-section forms a square. Each side
of the square is 0.020 m as shown in the figure. If each wire carries a current of 8.0 A in the direction
shown in the figure, determine the magnitude of the total magnetic field at P, the center of the square.
A) 5.1 × 10–5 T B) 1.1 × 10–4 T C) 1.7 × 10–4 T D) ----- 2.3 × 10–4 T E) zero tesla
- The figure shows two concentric metal loops, each carrying a current. The larger loop carries a
current of 8.0 A and has a radius of 0.060 m. The smaller loop has a radius of 0.040 m. What is the value
of a current in the smaller loop that will result in zero total magnetic field at the center of the system?
A) ----- 5.3 A B) 6.0 A C) 8.8 A D) 12 A E) 24 A
- Two loops carry equal currents I in the same direction. They are held in the positions shown in the
figure and project above and below the plane of the paper. The point P lies exactly halfway between them
on the line that joins their centers. The centers of the loops and the point P lie in the plane of the paper.
Which one of the figures below shows the position of a compass needle if the compass were placed in the
plane of the paper at P?
Answer: diagram with horizontal diamond, N on the left and S on the right
- Two long, straight wires are perpendicular to the plane of the paper as shown in the drawing. Each
wire carries a current of magnitude I. The currents are directed out of the paper toward you. Which one
of the following expressions correctly gives the magnitude of the total magnetic field at the origin of the
x, y coordinate system?
All answers are equations:
Correct answer: Mo x I / sqrt of 2pd
A long, straight wire is carrying a current of 5.0 A in the direction shown in the figure. The point P is
0.040 m from the wire.
- What is the direction of the magnetic field at point P due to the current in the wire?
A) to the right of page B) to the left of the page C) toward the bottom of the page D) into the plane of the page E) ----- out of the plane of the page
A long, straight wire is carrying a current of 5.0 A in the direction shown in the figure. The point P is
0.040 m from the wire.
- What is the magnitude of the magnetic field at the point P?
A) 1.3 × 10–5 T B) 1.9 × 10–5 T C) ----- 2.5 × 10–5 T D) 7.9 × 10–5 T E) 9.4 × 10–5 T
