1178864666Xuj

1178864666Xuj - Alvarado, Patrick – Homework 4 – Due:...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

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

Unformatted text preview: Alvarado, Patrick – Homework 4 – Due: Feb 16 2007, 11:00 pm – Inst: Opyrchal, H 1 This print-out should have 13 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points You have a potential difference of 6 V. How much work is done to transfer 0 . 34 C of charge through it? Correct answer: 2 . 04 J. Explanation: Let : V = 6 V and q = 0 . 34 C . The potential difference is V = W q W = V q = (6 V)(0 . 34 C) = 2 . 04 J . keywords: 002 (part 1 of 1) 10 points A uniform electric field of magnitude 286 V / m is directed in the positive x-direction. Sup- pose a 25 μ C charge moves from the origin to point A at the coordinates, (24 cm, 51 cm). x y 286 V / m O A (24 cm , 51 cm) What is the absolute value of the change in potential from the origin to point A ? Correct answer: 68 . 64 V. Explanation: Let : x = 24 cm , y = 51 cm , and k ~ E k = 286 V / m . The potential difference from O to A is defined as Δ V = V A- V O =- Z A O ~ E · d~s. We know that ~ E = (286 V / m) ˆ ı. We need to choose a path to integrate along. Because the electric force is conservative, it doesn’t matter which path we take; they all give the same answer. There are two choices of path for which the math is simple (see the figure below.) x y E O A ( x,y ) I I B I I Path I: V A- V O = ( V A- V B ) + ( V B- V O ) , From O to B, ~ E and d~s are both along the x-axis, so ~ E · d~s = E dx . From B to A, ~ E and d~s are perpendicular, so ~ E · d~s = 0. V A- V O =- Z B O ~ E · d~s- Z A B ~ E · d~s =- Z x E dx- Z y dy =- E Z x O dx =- E Δ x =- (286 V / m)(0 . 24 m) =- 68 . 64 V . The absolute value is | Δ V | = 68 . 64 V . Path II: In this case, ~ E · d~s = E cos θ ds. where cos θ = x l ⇒ x = l cos θ . V A- V O =- E cos θ Z l O ds =- E l cos θ =- E x. which is the same as the result for the other path. Alvarado, Patrick – Homework 4 – Due: Feb 16 2007, 11:00 pm – Inst: Opyrchal, H 2 keywords: 003 (part 1 of 1) 10 points The gap between electrodes in a spark plug is 0 . 087 cm. To produce an electric spark in a gasoline-air mixture, an electric field of 1 . 9 × 10 6 V / m must be achieved. On starting a car, what is the magnitude of the minimum voltage difference that must be supplied by the ignition circuit?...
View Full Document

This note was uploaded on 06/02/2010 for the course MGMT 121 taught by Professor Morozova during the Spring '10 term at NJIT.

Page1 / 6

1178864666Xuj - Alvarado, Patrick – Homework 4 – Due:...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online