91影视

FIGURE EX29.37 is a cross section through three long wires with linear mass density 50 g/m. They each carry equal currents in the directions shown. The lower two wires are 4.0 cm apart and are attached to a table. What current I will allow the upper wire to 鈥渇loat鈥� so as to form an equilateral triangle with the lower wires?

FIGURE EX29.37 is a cross-section through three long wires with a linear mass density $50g/m$. They each carry equal currents in the directions shown. The lower two wires are $4.0cm$apart and are attached to a table. What current I will allow the upper wire to 鈥渇loat鈥� so as to form an equilateral triangle with the lower wires?

A square current loop $5.0cm$on each side carries a$500mA$ current. The loop is in a $1.2T$ uniform magnetic field. The axis of the loop, perpendicular to the plane of the loop, is $30掳$掳 away from the field direction. What is the magnitude of the torque on the current loop?

A small bar magnet experiences a$0.020Nm$torque when the axis of the magnet is at $45掳$to a $0.10T$magnetic field. What is the magnitude of its magnetic dipole moment?

An electron moves along the $\text{z-axis}$with $v_x=1.0脳{10}^7\mathrm{m}/\mathrm{s}$. As it passes the origin, what are the strength and direction of the magnetic field at the $(x,y,z)$positions. (a) (1 cm, 0 cm, 0 cm) (b) (o cm, o cm, 1 cm)

(c) ( 0 cm, 1 cm, 1 cm)?

What is the current direction in the wire of FIGURE Q29.4? Explain.

a. What is the magnitude of the torque on the current loop in FIGURE EX29.40?

b. What is the loop鈥檚 equilibrium orientation?

A long wire carrying a $5.0$A current perpendicular to the xy-plane intersects the x-axis at$x=-2.0cm$. A second, parallel wire carrying a $3.0$A current intersects the x-axis at $x=+2.0$cm. At what point or points on the x-axis is the magnetic field zero if

(a) the two currents are in the same direction and

(b) the two currents are in opposite directions?

The two insulated wires in $FIGUREP29.42$cross at a ${30}^{鈭�}$angle but do not make electrical contact. Each wire carries a $5.0A$current. Points$1$and $2$are each $4.0$cm from the intersection and equally distant from both wires. What are the magnitude and direction of the magnetic fields at points$1$and$2$?

$FIGUREP29.42$ $FIGUREP29.43$

The two insulated wires in FIGURE P29.42 cross at a $30掳$angle but do not make electrical contact. Each wire carries a $5.0A$current. Points $1and2$are each $4.0cm$from the intersection and equally distant from both wires. What are the magnitude and direction of the magnetic fields at points $1and2$?