Transcript electrical energy.

1. Alternating current can be converted
to ________
direct current using a ______.
diode
2. Charges move easily through
a conductor but cannot move
_____________
an insulator
through ___________.
3. Draw a series circuit with two bulbs in
it.
4. transistor – semiconductor device that can be used as an
amplifier or a switch
5. solenoid –
6. resistance –
7. diode –
a coil of wire that produces a magnetic field
when carrying an electric current
opposition to the flow of electric current
semiconductor device that only allows electricity
to flow one direction. It can convert AC to DC.
8. static electricity – the buildup of electrical charges on an
object
9. magnet –
10. electricity -
any material that attracts iron or materials
which contain iron.
the flow of electrons
11. Draw a parallel circuit with three bulbs in it.
12. How does a circuit board work?
A circuit board is a collection
of hundreds of tiny circuits
mounted on a “board” that
together supply electric
current to the various parts
of an electronic device.
13. If a charged object goes near an electrically neutral
surface (but doesn’t touch it), then it can be charged
induction However, if there is direct
through ___________.
conduction .
contact, the surface is charged by _____________
14. If three solenoids all have the same number of
loops but different magnetic fields, what must be
different? More iron in the core, more current (like a bigger
battery), or shorter wires (less resistance)
repel each
15. If two charges are the same, they will _______
other.
16. If you rub a piece of plastic with felt, the plastic
becomes charged by _________
friction .
17. In a parallel circuit, no matter how many bulbs you
add, they will all have the _______
same brightness.
electrical discharge
18. Lightning is an example of ____________________;
this is the loss of static electricity as charges move off
an object.
semiconductor
19. Transistors and diodes are both made of _______________
material.
electrons it becomes
20. When an object gains or loses ____________,
charged.
21. Name 3 things that will decrease resistance.
a. use a thicker wire
b. use a shorter wire
c. cool the temperature
d. use a material that is a good
conductor
22. Name 3 ways to make an electromagnet stronger:
•
•
•
•
increase the number of coils in the solenoid
put more iron in the core
increase the current (bigger battery)
use a shorter wire for less resistance
23. Name 2 ways to increase the magnetic field of a solenoid.
• more coils
• put an iron core in the solenoid
• use more current (bigger battery)
24. Technology can be much smaller today because of
25. The law of electric charges states:
26. What is the difference between alternating and direct
current? In direct current, the charges always flow in one
direction. In alternating current, the charges
constantly switch directions, moving back and forth.
27. What is the difference between an electric motor and a
generator?
Electric motor converts Electrical to Kinetic energy.
Generator converts kinetic energy to electrical energy.
28. How does electromagnetic induction work?
Using electromagnetic induction, you can produce an electrical
current by changing a magnetic field. For example, if you move a
magnet around in a coil of wire, you can produce an electric
current.
29. A 100 Ω resistor is connected to a 20 V supply. What current
flows through it? (Show your work and include units!)
𝑉
20
𝐼= =
= 0.2 𝐴
𝑅
100
30. Calculate the voltage across a 300 Ω resistor when a current
of 0.004 A flow through it. (Show your work and include units!)
𝑉 = 𝐼 × 𝑅 = 0.004 × 300 = 1.2 𝑉
Factor in
Symbol
Ohm’s Law
Unit
Symbol for
Unit
31.
Resistance
R
Ohm
Ω
32.
Current
I
Ampere
A
33.
Voltage
V
Volts
V
34. You’re putting up a set of LED lights that are a bit fragile.
You’re adding them to a circuit with a brand new 9V battery.
Assuming there is no resistance from the attached ammeter or
the wires, how much resistance is there in each LED light?
𝑉
9
𝑅= =
= 0.6 Ω
𝐼
15
0.6 Ω / 2 = 0.3 Ω