2049_ch25B

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: at high voltage) (affordable) PHY2049: Chapter 25 19 Dielectric Mechanism is Due to Polarization E = 0, Dipoles randomly aligned E applied, partially aligns dipoles Aligned dipoles induce surface charges Surface charges partially cancel E field Yow! http://hyperphysics.phy-astr.gsu.edu/hbase/electric/dielec.html PHY2049: Chapter 25 20 ConcepTest Two identical capacitors are given the same charge Q, then disconnected from a battery. After C2 has been charged and disconnected it is filled with a dielectric. Compare the voltages of the two capacitors. Voltage lowered to V/κ (1) V1 > V2 (2) V1 < V2 (3) V1 = V2 C1 PHY2049: Chapter 25 C2 21 ConcepTest When we fill the capacitor with the dielectric, what is the amount of work required to fill the capacitor? (1) W > 0 (2) W < 0 (3) W = 0 Energy lowered to U/κ C1 C2 If U is total energy in capacitor Positive work: One “pushes in” dielectric ΔU > 0 Negative work: Capacitor “sucks in” dielectric ΔU < 0 PHY2049: Chapter 25 22 Capacitors in Circuits Multi-step process 2 + 3 in series C o Combine 2 & 3 ⇒ C/2 Ceq 1 + (2+3) in parallel Combine 1 & (2 & 3) ⇒ 3C/2 2 1C 3C o PHY2049: Chapter 25 23 Example: Find qi and Vi on All Capacitors C1 is charged in position A, then S is thrown to B position Initial voltage across C1: Initial charge on C1: V0 = 12 q10 = 12 x 4 = 48μC...
View Full Document

This note was uploaded on 07/31/2011 for the course PHY 2049 taught by Professor Any during the Summer '08 term at University of Florida.

Ask a homework question - tutors are online