Electrostatics Notes PDF

ELECTROSTATICS Electric Charge and Electric Field OBJECTIVES: a. Define Electrostatics. b. Identify the 2 kinds of charges. c. Identify the ways of charging a material. d. Relate Electrostatics to real life situations. Electrostatics – is a branch of Physics that deals with the phenomena...

ELECTROSTATICS Electric Charge and Electric Field OBJECTIVES: a. Define Electrostatics. b. Identify the 2 kinds of charges. c. Identify the ways of charging a material. d. Relate Electrostatics to real life situations. Electrostatics – is a branch of Physics that deals with the phenomena and properties of electricity at rest (stationary or slow-moving) ✓ It involves electric charges, the force between them, the field that surrounds them and their behavior in materials. The ancient Greeks discovered as early as 600 B.C. that after they rubbed amber with wool, the amber could attract other lighter objects. The word “electric” is derived from the Greek word elektron, meaning amber. In any charging process, charge is not created or destroyed, it is merely transferred from one body to another. This is the Law of Conservation of Charges. Neutral Atom In stable resting, an atom has the equal number of protons and electrons. Free electrons ▪ Free electrons are unbound to any atom ▪ They take part in heat and electricity ATOM ION ✓In ground state, atom is uncharged. ✓Losing or gaining electrons change the atom’s electric charge. ✓If an atom has fewer electrons than protons, it is positively charged ion. ✓If an atom has more electrons than the protons, it is negatively charged ion. Conductors - materials with high electron mobility (many free electrons) Insulators - materials with low electron mobility (very few or no free electrons) Things get charged by transferring electrons.  Charging by Charging by Charging by FRICTION CONDUCTION INDUCTION - charges an object without involves touching of a touching the object to any other The charging by friction charged particle to a charged object. process involves rubbing conductive material. This - the charged particle is held of one particle on way, the charges are near an uncharged conductive another resulting in transferred from the material. The charge flows electrons moving from charged material to the between two objects and the one surface to another. conductor. This method is uncharged conductive material This method is useful for useful for charging develop a charge with opposite charging insulators. conductors. polarity. Charging by Charging by Charging by FRICTION CONDUCTION INDUCTION The gain or loss of electron is called Ionization Polarization - is the separation of charges in an object that remains neutral. Charge of electron & proton 1 electron = (-) 1.6 x10-19 C 1 proton = (+) 1.6 x10-19 C  LEARNING CHECK How many electrons represent a charge of -70uC? PREFIXES Ex: Base Unit – meters (m) 9 nm = 9x10 m-9 9 um = 9x10 m-6  LEARNING CHECK How many electrons represent a charge of -70uC? GIVEN: Q = -70uC = -70.0x10-6C; e = 1.6 x10-19 C REQUIRED: n =? 𝑄 EQUATION: Q = ne; DERIVED: 𝑛 = 𝑒 70x10 C −6 SOLUTION: 𝑛 = subtract the exponent; cancel the unit of Coulombs 1.6 x10 −19 C 7.0x10 C −5 𝑛= 1.6 x10−19 C n = - 4.375 x10 or n = - 4.375 [−6−(−19)] x10[−6−(−19)] ANSWER: n = - 4.375 x1013 or - 4.375x1014  LEARNING CHECK What will be the electric charge 14 of 5x10 protons?  LEARNING CHECK What will be the electric charge of 5x1014 protons? GIVEN: Q = n = 5x1014; e = 1.6 x10-19 C REQUIRED: Q =? EQUATION: Q = ne SOLUTION: 𝑄 = (5x1014)(1.6 x10-19 C) Q = 8.01x10[14+(−19)] ANSWER: n = 8.01 x 10 C −5  LEARNING CHECK Find the electric Find the number charge of protons: of electrons: a. 3.19 x10 19 a. -150nC b. 1.9x10 6 b. -98uC REAL-WORLD APPLICATION 1. Lightning: How thunderstorms involve large-scale charge separation? 2. Photocopying: How photocopiers use electrostatic charges to attract toner particles to paper?