Plan for Today (AP Physics I) Go over Multiple Choice Questions/Review Review for Test

Understand and be able to describe static electricity Static electric about charge build up – excess or deficit of electrons Can get charge separation in conductors Conductors – allow electrons to move Insulators – prevent electrons from moving Can get charge by contact – causes like charges Or charge by induction – causes opposite charges

Describe the following balloon demonstrations Balloon on wall Charge build up on balloon from rabbit’s fur, charge separation on wall so we have – balloon, + section of wall Van de Graaff, can, and grounded sphere Can has charge separation, attracted to Van de Graaff, then charge transfer, repelled from Van de Graaff and attracted to grounded sphere, charge transfer. . . Packing peanuts in a conductor and insulator No charge on inside of a conductor = nothing happens Can get charges on inside of insulator because charges move there and stay

Also magic wand demonstration

Calculate the force on a charged particle

Calculate the electric field or the force from an electric field

Draw the electric field lines of one or more particles Like we did earlier Rules Begin at +, end at – Set scale Never cross lines Evenly distribute lines Use at least 4 or 5 Have arrows on lines (to negative charges)

Problems Types Worksheet with 3 charges, finding the force on one Drawing electric field lines for point charges (given a charge and a scale) Calculate the force and direction on a charge given the electric field strength Converting electrons and protons to Coulombs Pendulum problem

Find the force and direction acting on the charge farthest left in the following diagram.

Draw an diagram of the electric field between two charges close to each other, one with a charge of +2 C and the other with a charge of – 3 C.

Find the electric field at point P. If a + 3 C charge were placed there, what charge would act on the particle?

A charged particle is made up of 1. 2. 10^5 protons A charged particle is made up of 1.2 * 10^5 protons. What is the charge in Coulombs?

A charged particle has a charge of -2. 5 nC A charged particle has a charge of -2.5 nC. How many electrons make up the charge?

Two like charges are on either end of a pendulum so they reach equilibrium. The length of each side is .25 m. When at equilibrium, the string on the pendulum makes an angle of 12 degrees with the vertical. Find the charge of the two particles. Each particle has a mass of 3 g.

Two like charges are on either end of a pendulum so they reach equilibrium. The length of each side is .25 m. When at equilibrium, the string on the pendulum makes an angle of 12 degrees with the vertical. Find the charge of the two particles.

Find the force and direction acting on the charge farthest left in the following diagram.

Draw an diagram of the electric field between two charges close to each other, one with a charge of +2 C and the other with a charge of – 3 C.

Find the electric field at point P. If a + 3 C charge were placed there, what charge would act on the particle?

A charged particle is made up of 1. 2. 10^5 protons A charged particle is made up of 1.2 * 10^5 protons. What is the charge in Coulombs?

A charged particle has a charge of -2. 5 nC A charged particle has a charge of -2.5 nC. How many electrons make up the charge?