Question

A charging stand for an electric razor is [pwered by a standard 60Hz, 120 VAC (rms) wall outlet.

A. The charging base contains a 2- turn circular coil of wire with an area of 5.0 cm² . The two ends of the coil are connected to thte 120 VAC source. Assuming that the resistance of the coil is negligible, what is the rms value of d(phi)/dt in the base of the coil (magnetic flux)?

B. The razor also has a circular wire coil near its end. The area enclosed by the razor coil is 3.0 cm² . When the razor is inserted in the base (as shown), the razor and base coils are nested with a common central axis. The razor coil rests completely inside the base coil. Determine the rms value of d(phi)/dt in the razor coil. Assume that the magnetic field produced by the base coil is approximately uniform within its area.

C. The battery charging circuit in the razor requires a 6 VAC (rms) source. Assuming the razor coil provides this voltage, how many turns must the coil have?

D. The battery charging circuit draws 2.4 A of current while the battery is charging. If the inductive charger has a net efficiency of 85%, how much wall-plug power is used while the battery is charging?

Answer 1