4. Suppose the light bulb in the figure below is replaced with a short wire of zero resistance, and the resistance of the rails is hegligible. The only resistance is from the moving rod, which is iron (resistivity = 9.20 × 10-8 2.m). The rod has a cross-sectional area of 3.50 × 10-ºm² and moves with a speed of 1.00 m/s. The magnetic field has a magnitude of 0.045 T. What is the current n the rod? A Conducting rail 19 0of19 0of19 of19.0of19 0of19 0of19 oof19 0of19 0of19 0of19 o

4. A long straight wire of length 0.2 m is attached to a wall by a horizontal spring with a spring constant of k = 10 N/m. (Neglect gravity.) The wire is sitting in a uniform 0.5-T magnetic field (B) that points out of the page. When a current is turned on in the wire, the spring is stretched by 1.0 cm. What are the direction and magnitude of the current in the wire? (Recall that | Fspring = kx) A. 1.0 A, up wall B. 1.0 A, down C. 100 A, up D. 100 A, down E. 400 A, up wire 5. A long straight wire is carrying a current I = 5.0 A upward as shown in the figure below. A single, circular conducting loop of wire with a radius R = 0.02 m is located near the wire such that the closest distance from the wire to the loop's edge is 0.06 m. What must be the magnitude and direction of a current flowing around the loop such that the net magnetic field at the loop's center is zero? Iv /R A. 1.67 A, cw B. 1.67 A, cew C. 0.40 A, cw D. 0.40 A, ccw E. 1.00 A, cew 0.06 m O

3. The thin, uniform rod shown below has negligible mass and and a length of 0.200 m. It is attached to the floor by a frictionless hinge at point P. A horizontal spring with force constant k = 4.80 N/m connects the other end of the rod to a vertical wall. The rod is in a uniform magnetic field of B = 0.340 T directed into the plane of the page. There is a current of /= 6.50 A in the rod, as shown. a. Calculate the torque due to the magnetic force on the rod for an axis at point P. Do this by defining a differential magnetic force on the rod for a differential length dr at an arbitrary distance r from point P. Relate this differential magnetic force to its differential torque at point P. Then sum (i.e., integrate) the contributions from the entire length of the rod to get the total torque on the rod. b. Consider Hooke's Law, which states that the force exerted by the spring when stretched or compressed a length x is Fspring = kx. Now, given that the rod makes an angle of 53.0° with the…

1. A long solenoid that has 1,140 turns uniformly distributed over a length of 0.395 m produces a magnetic field of magnitude 1.00  10-4 T at its center. What current is required in the windings for that to occur? ______ mA 2. A wire with a weight per unit length of 0.077 N/m is suspended directly above a second wire. The top wire carries a current of 29.8 A and the bottom wire carries a current of 59.2 A. Find the distance of separation between the wires so that the top wire will be held in place by magnetic repulsion. _______ mm 3. A lightning bolt may carry a current of 1.00  104 A for a short time. What is the resulting magnetic field 170 m from the bolt? Suppose that the bolt extends far above and below the point of observation. _______  ?T 4. It is desired to construct a solenoid that will have a resistance of 4.80 Ω (at 20°C) and produce a magnetic field of 4.00 ✕ 10−2 T at its center when it carries a current of 4.35 A. The solenoid is to be constructed from copper wire having…

3. A zero-resistance rod of length 14.4 cm is being pushed along zero-resistance wires in a region where a uniform magnetic field of strength 2.00 T is directed out of the page as shown. If the wires and rod complete a circuit through a 2.90 N resistor then what velocity will the rod maintain if it is subjected to a constant pushing force of 22.0 N? Zero-resistance wires Push