Download Unit 2 Review Answers

Unit 3 Review Answers
1.
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
l)
m)
n)
o)
p)
deficiency
attract
excess
positively
positive
series
parallel
increases
energy
increases
decreases
nonrenewable
fire
ground
kilowatt-hour (not covered in much detail but in the notes)
useful output energy (don’t worry about this one)
2.
a)
b)
true
false (the amount of electric charge on an electron is the same as
that on a proton)
false (don’t worry about this one, sorry)
false (lightning does strike in the same place more than once)
false (primary cell converts chemical energy into electrical energy)
false (battery is a combination of two or more primary or secondary
cells)
true
false (when the filament of a bulb in a series circuit burns out, all the
other bulbs stop glowing)
false (the amount of electrical energy in a battery depends on the
number of cells, and the structure of the plates in the battery)
false (a 1000 W electric heater uses the same amount of electrical
energy as ten 100 W light bulbs in the same amount of time)
c)
d)
e)
f)
g)
h)
i)
j)
3.
a)
Both the electron and the proton are charged particles that are part
of every atom. An electron is a negatively charged particle and a
proton is a positively charged particle.
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
4.
6.
There are two kinds of electric charges, and they have the same
amount of charge. One kind of charge, the negative charge is
associated with the electron, and the other kind of charge, the
positive charge, is associated with the proton. Like charges repel, and
unlike charges attract.
An insulator does not allow electric charges to move along it, and
conductors will allow electric charges to flow along it.
When an object is charged by contact, the object being charged
receives the same kind of charge as is on the charging object. When
an object is charged by induction, the object being charged receives
the opposite kind of charge as is on the charging object.
When an open circuit condition exists, there is a break in the circuit,
and no current can flow through the circuit. When a closed circuit
condition exists, the circuit is complete, and current can flow
throughout the circuit.
In a series circuit, the electrical loads are connected in a single path,
one after the other. There is one path for current flow. In a parallel
circuit, the electrical loads are each connected in a separate branch
circuit to the source of electrical energy. There are as many paths
for current flow as there are branch circuits.
A dry cell is an electrochemical cell that has a moist paste as an
electrolyte. A wet cell is an electrochemical cell that has a liquid
electrolyte. Both types of electrochemical cells convert chemical
energy into electrical energy.
A primary cell is an electrochemical cell that can only be discharged,
and then discarded. A secondary cell is an electrochemical cell that
can be both discharged and recharged again many hundreds of times.
An ammeter measures electric current, and a voltmeter measures
electric potential or voltage drop.
Electrical energy is the energy transferred to an electrical load by
moving electrons. Electrical power is the rate at which that electrical
energy is used in an electrical load.
The joule is the SI unit for energy. The kilowatt-hour is the unit of
electrical energy used for measuring large amounts of energy. There
are 3 600 000 J in 1 kW-h (don’t need to know how to convert this.
b
d
7.
11.
12.
16.
17.
18.
19.
20.
24.
c
d
Two different substances build up static charges when rubbed
together because some substances have a stronger attraction for
electrons than others. When the two different substances are
rubbed together, the substance with the weaker attraction for
electrons, loses electrons to the substance with the stronger
attraction.
When one of the electrical loads is removed from a series circuit the
total current become zero. This occurs because there is only one path
for current flow in a series circuit, and so if one bulb is removed, the
path for current flow is broken.
a)
120V
b)
120V
c)
12V
a)
20 Ω
b)
She expected to measure a lower value of current because she
assumed that the element was an ohmic resistance, which it is
not. The resistance of stove elements increases with
temperature, and so the actual current is less at the normal
operating than when the element is cool. The expected current
is 0.30A
a)
2268 J
b)
40,320 J
30W
a)
SKIP THIS ONE – JUST KNOW HOW TO CALCULATE
ENERGY AND POWER AS WE DID IN THE NOTES AND
OTHER TEXTBOOK QUESTIONS LISTED