Download Circuits

Electricmagnetism
5/15/15
Major Topics of the Final
 Work and Power
 ~40%
 Conservation of Energy
 Waves
 ~40%
 Sound
 Light Reflection and
Refraction
 Electromagnetic Waves
 (Electromagnetic Induction)
 ~10%
True or False
1. When a battery no longer works, it is out of
charge.
2. A battery can be a source of charge in a
circuit. The charge which flows through the
circuit originates in the battery.
3. Charge becomes used up as it flows through a
circuit. The amount of charge which exits a
light bulb is less than the amount which
enters the light bulb.
True or False
4. When current runs through a wire a magnetic
field is produced.
5. Magnetism is produced by moving charges
6. The force of electromagnetism is stronger
then the force of gravity.
7. Electromagnetism can exert of force on an
object without touching it.
True or False
8. Charge flows through circuits at very high
speeds. This explains why the light bulb turns
on immediately after the wall switch is flipped.
9. The local electrical utility company supplies
millions and millions of electrons to our
homes everyday.
10. High voltage circuit means there is a large
current.
Conditions for a Circuit
 There must be a closed conducting path that
extends from the positive terminal to the
negative terminal.
 There must be an electric potential difference
across the two ends of the circuit.
Battery and Circuits
 A negative charge has the
least amount potential
Low PE energy at positive terminal
 A negative charge has the
greatest amount potential
energy at negative terminal
Voltage = Potential Difference
High PE
Waterslide vs. Circuit
Voltage Sources (batteries)
 Do work on each charge it encounters
 Which transfers into electric potential
energy
A “Dead” Cell Phone
When your cell phone “dies”:
 It no longer has the energy to power it
 It still has plenty of charge (electrons),
just not the ability to do work on the
charges
Electromagnetism
 Electromagnetism: the interaction of electric
currents or fields and magnetic fields.
 Electric current and moving charge is the
source of ALL magnetism
Voltage Sources Examples
 Ex 1) Low voltage and low current
 D-Cell battery: 1.5 V and 0.1 A
 Low waterfall with only trickle of water
flowing
Voltage Sources Examples
 Ex 2) High voltage and high current
 Power lines: 50,000 volts
and 65 A
 High waterfall with a river
of water flowing over it
Voltage Sources Examples
 Ex 3) High voltage and low current:
 Electric fence: 6000 V and 0.1 A
 High waterfall with only trickle of water
flowing
Voltage Sources Examples
 Ex 4) Low voltage and high current:
 Car battery: 12 V and 30 A
 Low waterfall with a gushing river of
water flowing
True or False Revisited
1. When a battery no longer works, it is out of
charge.
2. A battery can be a source of charge in a
circuit. The charge which flows through the
circuit originates in the battery.
3. Charge becomes used up as it flows through a
circuit. The amount of charge which exits a
light bulb is less than the amount which
enters the light bulb.
True or False
4. When current runs through a wire a magnetic
field is produced.
5. Magnetism is produces by moving charges
6. The force of electromagnetism is stronger
then the force of gravity.
7. Electromagnetism can exert of force on an
object without touching it.
True or False Revisited
8. Charge flows through circuits at very high
speeds. This explains why the light bulb turns
on immediately after the wall switch is flipped.
9. The local electrical utility company supplies
millions and millions of electrons to our
homes everyday.
10. High voltage circuit means there is a large
current.
Next Week
 Mon. 5/18/15 – Open note quiz with
handwritten notes only!
 Wed. 5/19/15 – Review is due, everyone need
to complete the review
 Thurs. 5/20/15 – Review for the final
 Fri. 5/21/15 – Final Exam can use one page (1
sided) of formulas and notes