o Course homepage, Ongoing Lectures, TT-system 

• Instructor’s weekly informal sessions:

Tu 3:30-4:20, RAS 213 ; Fri 4-5, RLM 5.104

Lecture: 15 Direct Current Circuits

Seat of emf

• Battery
• Other examples: dry cells, fuel cells, solar cells.

Conservation of energy

• Power delivered by a battery
• Power consumed by a resistor
• Comparison of brightness of light bulbs.

An old battery

• Internal resistance
• Terminal voltage

Kirchhoff’s rules:

• Natural direction

o Potential increase across a battery

o Potential drop across a resistor

• Unnatural directions: With opposite sign.
• A two loop circuit:

o Loop equations

o Node equation

o HW6: Q13-14.

Reminder:

• There is the regularly instructor’s informal section tomorrow, see time and place above.

• Contact instructor:

o MWF after class. Office hours: MW 12:50-1:30.

o TuFr after the instructor’s informal sessions:

· Tu4:20… RAS213

· Fr4:50… RLM5.104

o By email:

· Remember to include “303L” on the subject line.

· During week days, if I have not responded your email within 24hrs, I might have accidentally overlooked your email. To be sure that I get your email please send it again.

o If you would like to discuss your midterm performance, be sure bring your re-exam work with you, if possible, when you come.