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: 13 Currents and Ohm’s law

A simple electric circuit

• V and I (current)
• E=V/l and J=I/A (current density)

Ohm’s law

• Relationship between V and I
• Relationship between E and J

Resistor network

• Series and || connections
• Capacitor connections vs resistor connections

A model for Ohm’s law

• Current density in terms of drift velocity
• Ohm’s law as a consequence of v_thermal >> v_drift

Reminders:

• Midterm 1: Th(2/14), 7:00-8:30 (Be there by 6:50). Ch22-26,27*. Bel 328.

*You are only responsible for the qualitative knowledge of ch27 material covered in class.

• Links from the course homepage:

§ Advice for taking an exam

§ Advice for exam preparation

o Policies:

§ Calculator which has the capability of storing formula (e.g. graphic calculator) is allowed only after its memory is cleared. ( At the beginning of the exam, if you use a graphic calculator, please show your “memory clearance” to two neighbors).

§ For current semester, we use no-negative scoring grading policy. This supersedes the negative-scoring-policy discussed the “advice for taking an exam” link.

Preparation for midterm 1:

• Course summary: It contains the basic formula you need to know.

§ We suggest that you use it as a check-list as you study each chapter.

§ Download page 1 of the course summary, if you have not done it.

§ A fresh course summary will be included in your exam package. It is important for you to get familiar with it prior to the exam.

• Textbook: Skim through the text. Go through figures and examples (especially the ones related to your homework problems.)
• Homework problems: Understand the physics of each problem.
• Consult your class-notes for clarification.
• Pay special attention to the in-class-review of the unit.
• Review inclass-test (it) questions.