Physics 12

Mr. JeanNovember 3rd, 2011

The plan:• Video clip of the day• Field lines

Movember:• I am going to let you people decide.

– There are three options I’m considering.– They will be shown in the next 3 slides.

• Each cent counts for a vote.

• 1 penny = 1 vote. • 1 toonie = 200 votes.

Movember:• Collecting voting money until Friday.• Collecting money all month for the cause.• All money given will be directly donated to

the Cancer Society

• My goals– Minimum of 50 dollars raised– To out do Mr. Cooper either in beard or

money raised. .

Gravitational Field Lines:

• The gravitational field lines are directed radially inward toward a mass, m

.

Magnetic Field Lines:

• The magnetic field lines are closed loops leaving the N-pole of the magnet and entering the S-pole.

Electric Field Lines:

• A) The electric field lines from positive charge +q are directed radially outward.

(B) The electric field lines are directed radially inward toward negative point charge –q

Electric Field Lines:

• C) The electric field lines of an electric dipole are curved, and extend from the positive to the negative charge. At any point, such as 1, 2, or 3, the field created by the dipole is tangent to the line through the point.

Electric Field Lines:

• D) The electric field lines for two identical positive point charges are shown. If both of the charges were

negative, the directions of the lines would be reversed.

In class discussion:

1. Briefly explain the following with relation to charged particles or points of mass.

(a) action at a distance

In class discussion:1. Briefly explain the following with relation to charged particles or points of mass.

(a) action at a distance

In the action-at-a-distance theory, an object is believed to exert a force directly on another object some distance away.

In class discussion:

1. Briefly explain the following with relation to charged particles or points of mass.

(b) fields

In class discussion:1. Briefly explain the following with relation to charged particles or points of mass.

(b) fields

A field is the influence that an object (mass, charge, or magnet) has on the properties of the space around it.

In class discussion:

1. Briefly explain the following with relation to charged particles or points of mass.

(c) electric field intensity

In class discussion:1. Briefly explain the following with relation to charged particles or points of mass.

(c) electric field intensity

Electric field intensity is the electric force exerted per unit charge at a point in space.

In class discussion:

1. Briefly explain the following with relation to charged particles or points of mass.

(d) gravitational field intensity

In class discussion:1. Briefly explain the following with relation to charged particles or points of mass.

(d) gravitational field intensity

Gravitational field intensity is the gravitational force exerted per unit mass at a point in space.

In class discussion:

1.Briefly explain the following with relation to charged particles or points of mass.

(e) field lines

In class discussion:

1.Briefly explain the following with relation to charged particles or points of mass.

(e) field lines

Field lines indicate the direction of the field vectors throughout space, and their density indicates the strength of the field.

Question to do:1) Calculate the gravitational field intensity

at a height of 800.0 km from Earth’s surface.

2) Challenge Question: Two point charges, +36 C and –28 C, are 15.0 cm apart in a vacuum. What is the electric field intensity at a point midway between them?