# hw1 - Solution for Homework 1 Electric Charge and...

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Solution for Homework 1 Electric Charge and Introduction to Devices Solution to Homework Problem 1.1(Charges of Particles in Atoms) Problem: (a)Which particle in a neutral atom is positively charged? Select One of the Following: (a) The neutrons. (b) The electrons. (c-Answer) The protons. (d) The whole atom. (e) Nothing is positive in an atom. (b)Which particle in a neutral atom is negatively charged? Select One of the Following: (a-Answer) The electon. (b) The neutron. (c) The whole atom. (d) The proton. (e) Nothing in the atom is negativly charged. Solution to Part (a) The proton is positively charged. Grading Key: Solution to Part (a) 2 Points Solution to Part (b) The electron is negatively charged. Grading Key: Solution to Part (b) 2 Points Total Points for Problem: 4 Points Solution to Homework Problem 1.2(Number of Electrons to Make a Pico-Coulomb) Problem: A 10cm sphere charged with a car battery ( 12V ), picks up a positive charge of +100pC . How many excess or de±cient electrons are on the sphere? Select One of the Following: (a) 3 . 2 × 10 9 de±cient electrons (b) 1 . 1 × 10 14 excess electrons 1

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(c) 6 . 7 × 10 11 defcient electrons (d) 9 . 5 × 10 5 excess electrons (e-Answer) 6 . 3 × 10 8 defcient electrons Solution One 1pC = 1 × 10 - 12 C , so Q = 100pC = 1 × 10 - 10 C . The charge oF one electron is q = - 1 . 6 × 10 - 19 C , so the number oF defcient electrons, N needed to make Q is N = Q q = 1 × 10 - 10 C 1 . 6 × 10 - 19 C defcient electrons N = 6 . 3 × 10 8 defcientelectrons Total Points for Problem: 3 Points Solution to Homework Problem 1.3(Particle Emitted By Beta Decay)
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## This homework help was uploaded on 04/19/2008 for the course PHYS 2074 taught by Professor Stewart during the Spring '08 term at Arkansas.

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hw1 - Solution for Homework 1 Electric Charge and...

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