A.) An MP3 player operates with a voltage of 3.7 V, and is using 0.21 W of power. Find the current being supplied by the player's battery.
B.) A piece of Nichrome wire has a radius of 6.1 x 10-4 m. It is used in a laboratory to make a heater that dissipates 4.20×102 W of power when connected to a voltage source of 120 V. Ignoring the effect of temperature on resistance, estimate the necessary length of wire.