Principles of Technology
Chapter 10
Electric Current & Circuits
Quiz
1
Name______
1.
When a charge of
33
coulombs (Δq)
is moved
in a wire in
12
seconds (t),
calculate the electric
current (I)
in the wire.
(I=Δq/t)
a) 0.36
A
b)
0.45
A
c)
2.7
5 A
d)
21
A
2.
Calculate the charge (Δq)
that is moved in a wire in
2
minutes (t)
if an electric current of
15
A
(I)
moves through the wire
.
(I
=Δq/t)
(1 minute = 60 seconds)
a)
0.
7
5
C
b)
8
C
c)
30
C
d)
1
8
00
C
3.
How much time (t)
does it tak
e for a charge of
1
2
00
coulombs (Δq)
to move through a wire
with an electric current of
40
A (I)
in the wire.
(I=Δq/t)
(1 minute = 60 seconds)
a)
60
s
b)
0.5
minute
c)
3
hours
d) 2
.
5
minutes
4.
When a
wire has a potential difference of
11
2
volt
s
(
V
)
and a current of
3.
5 A
(
I
)
,
calculate the
resistance
(
R
)
in the wire.
(
R
=
V/I
)
a) 0.
5
Ω
b)
4
.1
Ω
c)
32
Ω
d)
92
Ω
5.
What is the potential difference (V) in a silicon
rod
with a
current of
25
A (I)
and a
resistance of
45
Ω (R)
.
(R
=V/I)
a)
56
V
b)
1
8
0
V
c)
70
0
V
d
)
1
100
V
6.
What is the current (I)
in a metallic coil
with a potential
difference of
1
2
0 volts (V)
and a
resistance of
2300
Ω (R).
(R=V/I)
a) 0.05 A
b)
1.15
A
c) 20 A
d)
32
A
7.
Which of the following mat
erials
has the greatest
resistance
to electric current flow?
a) glass
b)
iron
c)
copper
d) silicon
8.
Calculate the resistance (Ω)
at 20°C of
an iron
wire
with a resistivity of
9.7 x l0

8
Ω∙m (ρ)
that
is
3
.5
meter long
(L
)
and has a cross

sec
tional area of
9.7
x l0

2
m
2
(A)
.
(R
=
ρ∙L/A
)
a)
2
.0 x l0

3
Ω
b)
1
.5 x l0

5
Ω
c)
3.5
x 10

6
Ω
d)
7
.0 x l0

7
9.
Calculate
the resistance (Ω)
at 20°C of a silicon rod with a resistivity of
0.9
Ω∙m (ρ
) that is
4
.5
meter long (L)
and has a cross

s
ectional area of
0.
05
m
2
(A)
.
(R = ρ∙L/A)
a) 0.
2 Ω
b)
4
Ω
c)
81
Ω
d)
280
Ω
10.
Which set of statements is true:
i.
Superconductors, lose all of their resistance when cooled to very low temperatures
ii.
Superconductors conduct better at higher
temperatures.
iii.
Energy is
gained
in superconductors because the heat lost by resistance is
is converted to electricity
.
iv.
Metallic substances are good conductors
but have more
resistance than superconductors
when both
are
at very low temperatures.
v.
Long, th
in wires have greater resistance than short, thick wires made of the same metal.
a) i , iv, v
b) i , iii, iv
c) ii , iii, v
d) i , iii, v
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