Transcript Electricity Review_1

Static vs
Current
Circuit
Elements
Resistance
is V / I
Energy
switch
Make and
use
How to
generate
100 100 100 100 100 100
200 200 200 200 200 200
300 300 300 300 300 300
400 400 400 400 400 400
500 500 500 500 500 500
This object would be:
+++---+-+
--++-++++
Positively charged
Law of Charges states: (3)
1. Unlike charges attract
2. Like charges repel
3. Charged objects attract uncharged
neutral objects
List 2 good conductors
Gold, copper, nickel platinum,
silver
List 2 good insulators
Cotton, glass, rubber, paper, plastic,
porcelain
What does grounding an
object do?
Using a conducting wire to the ground,
electric charges can be neutralized. It
provides a path for the charge.
Draw a lamp.
(see the board)
Draw series circuit with a
battery, lamp and motor.
(see the board)
Draw a parallel circuit with 2
switches, battery, and 2 lamps.
(see the board)
Draw a parallel circuit where the
lamp stays on and the motor can be
turned on or off independently.
(see the board)
Explain the circuit
components using a
metaphor (water,
highway, or hallway)
Water: water held behind a
dam is voltage; water flow is
the current; water wheel is the
load; spill-gates control the
flow like a switch.
What is the unit of
resistance?
ohm
What is Ohm’s Law?
R = V/I
What is a resistor used for?
To control the current
in the circuit.
What is the difference
between resistors and
variable resistors?
Resistors regulate a certain amount of
current. Variable resistors are
adjustable in the amount of current
they resistance.
What is the resistance of a
light bulb that uses 2A in a
120V circuit.
60 ohms
A wall heater performs this
energy conversion.
Electrical to thermal
A motor does this energy
conversion
Electrical to mechanical
A generator does this energy
conversion.
Mechanical to electrical
Why can’t an energy
conversion ever be 100%
efficient?
Energy is always lost to friction.
Explain how a thermocouple
works.
A wire is connected in a loop (2 different
metals). One side is in a cold temperature,
the other is a warm temperature. The
difference in temp results in the flow of
electrons to try to balance the temp
difference. As soon as you have electron
flow, you have electricity.
How does an electrochemical
cell generate electricity?
Chemical reaction
Why do you need an electrode
and electrolyte?
Electrode: provides the electrons
Electrolyte: passes the electrons
from one electrode to the other.
What is the difference
between a motor and a
generator?
A motor uses electricity and a
generator makes it.
How can you use a coil of wire
and a magnet to generate
electricity?
Pass the magnet in and out of the coil
of wire. This pushes and pulls the
electrons creating electricity.
Trace the path of electricity
through a DC Motor.
1. Electricity enters the negative battery
terminal
2. Travels through a brush
3. Enters one side of the split ring commutator
4. Goes into the armature causing it to become
an electromagnet.
5. Exits other side of armature, travelling into
the other side of the commutator.
6. Into in the opposite brush and out the positive
battery terminal.
What is the difference between a step-up
and step down transformer?
Step up = increase voltage
Step down = decrease voltage
What is the purpose of a circuit
breaker?
It acts as a switch to control the
amount of electricity in a circuit.
What are the three wires that
enter your house?
White (neutral), black (hot), and
bare copper (ground)
What is a transistor?
An electronic switch in a modern
digital device that can be turned off
by electric signals.
List 4 methods of energy generation.
Thermoelectric (fossil fuels,
biomass), windmills, solar,
hydroelectric, thermonuclear