A 10-cm-long wire is pulled along a U-shaped conducting rail in a perpendicular magnetic field. The total resistance of the wire and rail is 0.20 Ω. Pulling the wire with a force of 1.0 N causes 4.0 W of power to be dissipated in the circuit.a. What is the speed of the wire when pulled with a force of 1.0 N?b. What is the strength of the magnetic field?

An electron moves with a speed of 2.5×107 m/sm/s in the directions shown in the figure. A 0.40 TT magnetic field points in the positive x-direction.(Figure 1) A. What is the magnitude of the magnetic force in figure (a)? F=  B. What is the direction of the magnetic force in figure (a)? a. +z direction b. -z direction c. +zy direction d. -zy direction  C. What is the magnitude of the magnetic force in figure (b)? F =  D. What is the direction of the magnetic force in figure (b)? a. +zy direction b. -zy direction c. +z direction d. -y direction

A proton enters a uniform magnetic field of strength 1.2 T at a right angle to the field. What will be the frequency, in Hz, of the proton's resultant circular motion? The charge of a proton is 1.602 x 10-19 C, and the mass of a proton is 1.67 x 10-27 kg.   a. 14 MHz   b. 26 MHz   c. 10 MHz   d. 18 MHz   e. 22 MHz

An experimentalist fires a beam of electrons, creating a visible path in the air that can be measured. The beam is fired along a direction parallel to a current-carrying wire, and the electrons travel in a circular path in response to the wire’s magnetic field. Assuming the mass and charge of the electrons is known, what quantities would you need to measure in order to deduce the current in the wire?  a. the radius of the circular path b. the average distance between the electrons and the wire  c. the velocity of the electrons d. two of the above e. all of the above