1. Physics 121: Electricity & Magnetism – Lecture 7 Carsten Denker NJIT Physics Department Center for Solar–Terrestrial Research

2. February 28, 2007Center for Solar-Terrestrial Research Work, Energy, and EMF How do we “pump” charge?  EMF (electromotive force) device! Definition of EMF  Battery  Generator  Solar cells  Fuel cells  Thermopiles

3. February 28, 2007Center for Solar-Terrestrial Research Single Loop Circuits n resistances in series  Loop rule  Resistance rule  EMF rule Energy/potential method

4. February 28, 2007Center for Solar-Terrestrial Research Potential Difference Power of an EMF device To find the potential difference between any two points in a circuit, start at one point and traverse the circuit to the other, following any path, and add algebraically the changes in potential that you encounter.

5. February 28, 2007Center for Solar-Terrestrial Research Multi-Loop Circuits n resistances in parallel Junction Rule: The sum of the currents entering any junction must be equal to the sum of the currents leaving that junction. Table 28 – 1!