29. Sources of Magnetic Field

A 175-g model airplane charged to 18.0 mC and traveling at 2.8 m/s passes within 7.8 cm of a wire, nearly parallel to its path, carrying a 25-A dc current. What acceleration (in g’s) does this interaction give the airplane?.

Sharona places two magnetic toy vehicles carrying parallel currents very close to each other. According to the physics of magnetic force between parallel currents, what will happen next?

Two closed loops $A$ and $C$ are placed near a long straight wire carrying a current $i$. If the current in the wire flows upward, which statement correctly describes the net magnetic force experienced by each loop due to the wire's magnetic field?

Which of the following statements best explains why two long, straight, parallel wires carrying currents in the same direction attract each other, assuming the wires are made of a magnetic metal?

Which statement best describes what can be inferred about magnetic domains from the fact that they are arrangements of atoms?

Four long, parallel power lines each carry 100 A currents. A cross-sectional diagram of these lines is a square, 20.0 cm on each side. For each of the three cases shown in Fig. E28.25, calculate the magnetic field at the center of the square.

Two long, straight, parallel wires carry currents in the same direction. At point $z$, which is located exactly midway between the wires, what is the direction of the net magnetic field?

Two long parallel wires carry currents of $I_1$ and $I_2$ in the same direction and are separated by a distance $r$. What is the direction of the magnetic force on wire 1 due to wire 2?

Two very long wires of unknown lengths are a parallel distance of 2 m from each other. If both wires have 3 A of current flowing through them in the same direction, what must the force per unit length on each wire be? 

BONUS:Is the mutual force between the wires attractive or repulsive?

In Fig. 28–57 the top wire is 1.00-mm-diameter copper wire and is suspended in air due to the two magnetic forces from the bottom two wires. The current is 35.0 A in each of the two bottom wires. Calculate the required current in the suspended wire (M).

Two parallel wires carry a current in the same direction. There is □ between the wires.

Two long, parallel wires are separated by a distance of 0.400 m (Fig. E28.29). The currents I₁ and I₂ have the directions shown. Each current is doubled, so that I₁ becomes 10.0 A and I₂ becomes 4.00 A. Now what is the magnitude of the force that each wire exerts on a 1.20 m length of the other?

Two long, parallel wires are separated by a distance of 0.400 m (Fig. E28.29). The currents I₁ and I₂ have the directions shown. Calculate the magnitude of the force exerted by each wire on a 1.20-m length of the other. Is the force attractive or repulsive?

(II) Let two long parallel wires, a distance d apart, carry equal dc currents I in the same direction. One wire is at 𝓍 = 0, the other at 𝓍 = d, Fig. 28–41. Determine $\overrightarrow{B}$ along the 𝓍 axis between the wires as a function of 𝓍.