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Announcements. Homework for tomorrow… (Ch . 26 Probs. 19, 23, & 40) CQ3: E 3 = E 4 , E 2 , E 1 CQ4: a) 3 b) 1 c) 90 nC 26.9: 1.3 x 10 5 N/C , 0.0 N/C , 1.3 x 10 5 N/C 26.10: 4.0 x 10 -8 C Office hours… MW 12:30-1:30 pm TR 9-10 am F 10-11 am
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Announcements • Homework for tomorrow… (Ch. 26 Probs. 19, 23, & 40) CQ3: E3=E4 , E2 , E1 CQ4: a) 3 b) 1 c) 90 nC 26.9: 1.3 x 105 N/C , 0.0 N/C , 1.3 x 105 N/C 26.10: 4.0 x 10-8 C • Office hours… MW 12:30-1:30 pm TR 9-10 am F 10-11 am • Tutorial Learning Center (TLC) hours: M 8-1 pm, 3-6 pm, W 8-1 pm, 2-6 pm TR 8-6 pm, F 8-2 pm
Chapter 26 The Electric Field (The Parallel-Plate Capacitor & Motion of a charged particle in an E-field)
Last time… • E-fieldof a ring of radius R & charge Q on the z-axis.. • E-fieldof a disk of radius R & charge Q on the z-axis.. • E-field of an infinite plane… • E-field of a sphere (of radius R) of charge Q..
Quiz Question 1 At the dot, the y-component of the E-field due to the shaded region of charge is
26.5: The Parallel-Plate Capacitor Two electrodes, one with charge +Q and the other with –Q, placed face-to-face a distance d apart..
The Parallel-Plate Capacitor • What’s the E-field between the plates? • What’s the E-field outside of the plates? ------------------------------------------------------- +++++++++++++++++++++++++++++++
The Parallel-Plate Capacitor • What’s the E-field between the plates? • What’s the E-field outside of the plates? ------------------------------------------------------- +++++++++++++++++++++++++++++++
Uniform E-Field… • is the same in magnitude and direction at every point in space. • Parallel-plate capacitors produce uniformE-fields
26.6: Motion of a Charged Particle in an E-Field • The E-field exerts a force on a charged particle… • If it’s the only force acting on q, then… • If it’s a uniform E-field, then…
i.e. 26.8: An e- moving across a capacitor Two 6.0 cm diameter electrodes are spaced 5.0 mm apart. They are charged by transferring 1.0 x 1011e-s from one electrode to the other. An e- is released from rest at the surface of the negative electrode. How long does it take the e- to cross to the positive electrode? What is its speed as it collides with the positive electrode? Assume the space between the electrodes is vacuum.
i.e. 26.9: Deflecting an e- beam An e- gun creates a beam of e-’s moving horizontally with a speed of 3.3 x 107 m/s. The e-’s enter a 2.0 cm long gap between two parallel electrodes where the electric field is E = -(5.0 x 104 N/C) jhat. In which direction, and by what angle, is the electron beam deflected by these electrodes?