Announcements Homework for tomorrow… Ch. 25, Prob. 65 & Ch. 26, CQ 2, Probs. 4 & 6 CQ12: 3 rd line to the right of -q 25.18: F A =(7.2 x N) jhat, F B =-(7.2 x N) jhat 25.40: F=(1.2 x N) jhat Office hours… MW 12:30-1:30 pm TR 9-10 am F 1-2 pm Tutorial Learning Center (TLC) hours: ??
Chapter 26 The Electric Field (E-Field Models & E-Field of Multiple Point Charges)
The Electric Field is defined as… The magnitude of the E-field of a pt. charge is… Last time… +
Permittivity constant.. Define a new constant.. so that… Coulomb’s Law becomes…
Electric Fields & Superposition P, what is the E-field? P q1q1 q2q2 q3q3
Electric Fields & Superposition P, what is the E-field? P, P q1q1 q2q2 q3q3
q3q3 q1q1 i.e. 26.1: The electric field of 3 equal pt. q’s Three equal positive point charges q are located on the y- axis at y = 0 and at y = ±d. What is the electric field at a point on the x-axis? q2q2 d d P x
i.e. 26.1: The electric field of 3 equal pt. q’s Three equal positive point charges q are located on the y- axis at y = 0 and at y = ±d. What is the electric field at a point on the x-axis? q2q2 q3q3 q1q1 d d P x
An Electric Dipole is… 2 equal but opposite charges separated by a small distance. Kinds: Permanent Electric Dipole (i.e. H 2 O) Induced Electric Dipole (i.e. polarized atom) Dipole Moment… The Electric Field of a Dipole -q +q s
The Electric Field of a Dipole Calculate the electric field of a dipole on the axis of the dipole… -q +q s x y P
The Electric Field of a Dipole Calculate the electric field of a dipole on the axis of the dipole… Notice: r is distance measured from the center of dipole. -q +q s x y P
The diagram shows a positive charge +q and a negative charge –q with the same magnitude. The electric field at point P on the plane that bisects the dipole is: 1. Up. 2. Down. 3. Left. 4. Right. 5. Zero. Quiz Question 1 -q +q P
The Electric Field of a Dipole Calculate the electric field of a dipole in the plane that bisects the dipole. -q +q s x y
The Electric Field of a Dipole Calculate the electric field of a dipole in the plane that bisects the dipole. s x y -q +q
The Electric Field of a Dipole Calculate the electric field of a dipole in the plane that bisects the dipole. Notice: field is opposite to p & half the strength of on-axis field. -q +q s x y