THE FIELDS OF MOVING CHARGES — Edward Purcell & David Morin
Physics — E&M · d-cell
Problem
D-cell **
The common 1.5 volt dry cell used in flashlights and innumerable other devices releases its energy by oxidizing the zinc can which is its negative electrode, while reducing manganese dioxide, MnO2, to Mn2O3 at the positive electrode. (It is called a carbon--zinc cell, but the carbon rod is just an inert conductor.) A cell of size D, weighing 90 g, can supply 100 mA for about 30 hours.
(a) Compare its energy storage, in J/kg, with that of the lead--acid battery described in the example in Section 4.9. Unfortunately the cell is not rechargeable.
(b) How high could you lift yourself with one D-cell powering a 50 percent efficient winch?