HIGH SCHOOL PHYSICS 2 COURSE. ( SPH 4U1/SPH OA1)

## UNIT 5: GRAVITATIONAL, ELECTRIC AND MAGNETIC FIELDS.

Even though no one has been able to link gravitational and electric fields together, we will see how they follow remarkably similar patterns. Gravitational fields are of great concern when dealing with orbits, rocketry and interplanetary probes. Electric fields are less familiar, but have many practical applications in devices that we use every day. In this unit we will learn the fundamentals of how these fields work.

It is very important that you read the pages in the textbook that go along with the lessons as some of the topics are confusing.

 Lesson Topic Text (Nelson) Homework & Resources Text (Martindale) 1. Force fields, Gravitational Energy Derivation of gravitational potential energy Gravitational Field Intensity. 274-277 285-288 Excellent PowerPoint summary of physics p293#8 no,11 2. Orbits, orbital speed, escape velocity, geosynchronous orbits, total energy (maybe elliptical orbits - make ellipses) 145-151 278-284 288-294 p300 #5,8,10a,17 read: Elliptical Orbits and Standard Assumptions If you can't get to these links, email me. 3. Fg and g as vectors. Work period 4. Electric Force (Fq). Coulomb's Law read §7.1 - 7.3 5. Quiz - gravity Electric Fields (java applets), field lines, Sample calculations Summary of electrostatics 337-348 See: Electric Field diagrams and Electric Fields Applet Read electric_fields.pdf worksheet based on applet 6. Electric Fields (cont.) (perpendicular to conductors, shielding, point discharges) p343 #1a,4; also 4 questions at end of lesson Assignment #2 7. Electric Potential Energy, Work done moving charges 349 8. Electric Potential and Voltage Equipotential Lines Millikan Experiment (p360-364) 350-355 Pseudo-Lab: p374 part 2 9. Quiz - Electric fields and equations Equipotential Pre-Lab Do pre-lab 10. Equipotential LAB Lab writeup Read G E M fields comparison 11. Omit thisCapacitance - ** not written up yet. May take a couple of days. ... 12. Review 13. Unit Test

Assignment #1: p 300 #5,8,10,17

Assignment #2: Find 3 uses of electric fields in technology, i.e. 3 devices that use electric fields.
– no, perhaps, just find one, write it on a list so that no one else can use it. Write up a summary (one or two pages) with a diagram (mandatory) explaining how it works. Hand out to class, and explain verbally how it works. I’ll add these to the test (not necessarily relying solely on the handouts, but also on any missed information as to how the device works ? you need to do a good job).

## Objectives (or Outcomes): Gravitational, Electric and Magnetic Fields Unit

By the end of this unit the student will be able to:

define and describe the concepts (quantities) and units related to fields: potential energy, gravitational field intensity, electric field, magnetic field, magnetic induction
state and apply Coulomb's Law and Newton's Law of Universal Gravitation (in static cases)
determine the strength of the gravitational field at some point outside a spherically symmetric mass
deterime the velocity, centripetal acceleration and period of orbit for an object in a circular orbit
for a general orbit, use conservation of angular momentum to determine the velocity and radial distance at any point in the orbit (not done 2003)
apply conservation of angular momentum and conservation of energy to relate the speeds at the two extremes of an elliptical orbit (not done 2003)
state Kepler's three laws of planetary motion

Electric fields and forces:
define electric field in terms of the force on a point charge
calculate the magnitude and direction of a force on a + or - charge placed in a specified field
given a diagram on which the electric field is represented by flux lines, determine the direction of the field at a given point, identify locations where the field is strong and weak, and identify where positive or negative chrages must be present
analyse (??) the motion of a particle of specified charge and mass in a uniform electric field
describe the electric field produced by a point charge
analyse, illustrate with field and vector diagrams (one diagram or two?) the electric field and the forces produced by a single point charge, two point charges, parallel plates
determine the electric force that acts between specified point charges
use vector addition to determine the electric field produced by two or more point charges
compare the properties of G, E and M fields, illustrating the direction of the fields ...
calculate the electric force needed to balance gravitational force (Millikan's oil drop experiment)

Electric potential:
calculate the electrical work done on a charge to move it through a specified potential difference
given a sketch of equipotential lines for a charge configuration, determine the direction and approximate magnitude of the electric field at various locations
apply conservation of energy to determine the speed of a charged particle that has been accelerated through a specified potential difference
calculate the potential difference between two points in a uniform electric field and state which is at the higher potential
determine the electric potential in the vicinity of one or more poitn chrages
apply the concept of electric potential energy; compare it to gravitational potential energy

Conductors:
describe and explain the electric field that exists inside and on the surface of a charged conductor (e.g. a wire or co-axial cable)
explain why a conductor must always be an equipotential; apply this principle to analyze what happens when conductors are brought in contact
determine the direction of the forceon a chargedparticle brought near an uncharged or grounded conductor
describe the process of charging by induction

Capacitors:
define capacitance; relate voltage, stored charge, and stored energy for a capacitor
using parallel plade capacitors: describe the electric field inside the capacitor, relate field strength to potential difference and plate separation
determine how changes in dimension affect the value of the capacitance
calculate equivalent capacitance of a series or parallel combination
describe how stored charge is divided between two capacitors connected in parallel
determine the ratio of voltages for two capacitors connected in series
calculate voltage or stored charge for a DC  RC circuit at equilibrium
using RC circuits, determine voltages and currents immediately after a switch has been closed

Magnetic fields:

determine the net force, and subsequent motion, of particles in some sort of field, either from experiment or computer simulation

Legend:
Ministry of Education requirement
AP Physics requirement
Teacher's extra requirement

Last updated: Sept 2003