Transcript Electric Currents and Circuits Review

Electric Currents and Circuits
Review
How much work is done to
transfer 0.18 C of charge
through a potential difference of
12 volts?
Ans. 2.16 J
A spark will jump through dry
air when the electric field is
larger than 1000 volts/m. If two
parallel plates have a potential
difference of 5000 V, what is
the minimum distance between
them to prevent discharge?
Ans. 5 m
A certain X-ray tube uses
125,000 volts to accelerate
electrons to produce X-rays.
What is the kinetic energy of the
electrons just before they strike
the tungsten metal?
Ans. 2 x 10-14 J
Which of the
following
arrangements of
three identical
resistors will
produce the
lowest value of
current through
the battery?
Ans. A
Which of the
following
arrangements of
three identical
resistors will
produce the
largest value of
current through
the battery?
Ans. C
Which graph could
represent I vs. V in a simple
circuit?
Ans. C
What is the current in the circuit?
V
60 V
A2
A1
10 
Ans. 3 A
10 
An electric heater draws 15 A when
connected to a 120 V source. It
is operated for 5 hours every
day. At a cost of $0.08 per kWh,
how much does it cost to
operate the heater for 30 days?
(1kWh = 3.6  106 J)
Ans. $21.60
What is the voltage drop across the
left resistor?
V
60 V
A2
A1
10 
Ans. 30 V
10 
If R3 is 150 , what is the
current through it?
R2
80 V
R1
240 
A
Ans. 0.53 A
1A
R3
V
What is R1?
R2
80 V
R1
240 
A
Ans. 80 
1A
R3
V
While stringing a line of Christmas
tree lights you notice that one of
the bulbs has burned out. The
rest of the bulbs remain lit. The
bulbs must be wired in
• Series
• Parallel
• Cannot be determined
Ans. parallel
What is the power
dissipated by R2?
R2
80 V
R1
240 
A
Ans. 26.7 W
1A
R3
V
What is the current through the 5 
resistor?
10 
5
100 V
15 
Ans. 3.33 A
What is the total resistance
of this circuit?
10 
5
100 V
15 
Ans. 30 
What is the voltage V2?
60 V
Ans. 60 V
10 
5
15

What is the voltage drop V3?
10 
5
100 V
15 
Ans. 50 V
What is the total resistance of
this circuit?
60 V
Ans. 2.73 
10 
5
15

What is the current in the
rightmost branch?
60 V
Ans. 4 A
10 
5
15

Which diagram shows a possible
flow of current in part of a circuit?
Ans. A
What is the current through the
battery in this circuit?
60 V
Ans. 22 A
10 
5
15

An electrical heater raises the
temperature of a bucket of
water. If 6000 J of energy is
absorbed by the water from the
heater in 30 s, what is the
minimum power rating of the
heater?
Ans. 200 W
Which circuit shows the correct
setup for the ammeter and
voltmeter in a parallel circuit?
Ans. B