Download Circuit Theory test1

NAME__________________________
PHYSICS 335: TEST ON POTENTIAL DIFFERENCE, CURRENT, RESISTANCE AND POWER
MULTIPLE GUESS: CIRCLE the LETTER of the MOST correct choice for each of the
following questions:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
A wire of length L has a resistance R. If two-thirds of the wire is cut
off and thrown away, so that its length is now (1/3)L, what is this
wire's new resistance? a. R, b. (1/3)R, c. (1/9)R, d. 3R, e. 9R.
The resistivity of wire depends on - a. composition, b. length, c. area
of cross section, d. none of these, e. all of these.
A wire of L length and A cross section is cut in half and the two pieces
are taped together side-by-side, so that the area of cross section is
now 2A and the length is 1/2L. If the original wire had a resistance of
R, what is the resistance now? a. R, b. (1/2)R, c. (1/4)R, d. 2R,
e. 4R.
A 120V, 60 W bulb has a resistance of - a. 2 Ohm, b. 60 Ohm, c. 120 Ohm,
d. 240 Ohm, e. none of these.
The bulb in the previous problems has - a. more resistance than a 120
Volt 25 Watt bulb, b. more resistance than a 120 V, 100 Watt bulb,
c. the same resistance as a 220 Volt, 60 Watt bulb.
If the bulb in the previous problem were put across a 220 V power
supply, it would dissipate - a. more power, b. less power, c. the same
power.
The unit (Volt)(Amp) is the same unit as the - a. Ohm, b. Joule, c. Watt
d. Joule/Coul.
The unit Volt/Amp is the same unit as the - a. Ohm, b. Joule, c. Watt
d. Joule/Coul.
The unit Amp2Ohm is the same unit as the - a. Ohm, b. Joule, c. Watt
d. Joule/Coul.
A 1200 watt heater operates on a 120 Volt line for one hour. What is the
current passing through the heater? a. 5 amps, b. 10 amps, c. 1 amp,
d. 360 amps, e. none of these.
Ohm's law states that - a. The current through a resistor is directly
proportional to the applied voltage across the resistor, b. The voltage
across a resistor is directly proportional to the current passing
through the resistor, c. the resistance is the constant of
proportionality between potential difference and current, d. all of the
above.
A resistor is a device which - a. aids the flow of curent in a circuit,
b. always has the same potential difference across its ends, c. is a
type of "electron pump", d. restricts the flow of current in the
circuit.
In which circuit is the potential difference across the smallest
resistor the largest? a. series circuit, b. parallel circuit, c. both,
d. neither.
In which circuit is the current through each resistor increased if the
potential difference across the whole circuit is increased from 110V to
220V? a. series circuit, b. parallel circuit, c. neither, d. both.
In which circuit is the voltage drop the same across each resistor?
a. series circuit, b. parallel circuit, c. neither, d. both.
The potential difference across three batteries is greatest if they are
connected in - a. series, b. parallel, c. neither, d. both.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
In which circuit does the resistance decrease when a resistor is added?
a. series circuit, b. parallel circuit, c. neither, d. both
Two batteries will supply more voltage to the circuit AND last longer at
the same time if they are connected in - a. series, b. parallel,
c. neither, d. both.
In which kind of circuit is the current the same throughout? a. series
circuit, b. parallel circuit, c. neither, d. both.
In which circuit does the voltage drop across each resistor increase
when more resistors are added? a. series circuit, b. parallel circuit
c. neither, d. both.
In which kind of circuit is the total resistance less than the
resistance of the lowest value resistor in the circuit? a. series
circuit, b. parallel circuit, c. neither, d. both.
In which kind of circuit is the total resistance equal to the sum of the
individual resistances? a. series circuit, b. parallel circuit,
c. neither, d. both.
In which circuit does no current flow in the entire circuit when one
resistor is turned off or broken? a. series circuit, b. parallel
circuit, c. neither, d. both.
In which circuit does the current decrease in the other resistors when
more resistors are added to the circuit? a. series circuit, b. parallel
circuit, c. neither, d. both
A 5 Ohm resistor is connected in parallel with a 10 Ohm resistor and a
15 Ohm resistor. Which will have the most current pass through it?
a. the 5 Ohm resistor, b. the 10 Ohm resistor, c. the 15 Ohm resistor,
d. the current will be the same in each resistor.
If the 5 Ohm resistor is removed from the parallel circuit in the
previous question, what happens to current through the 10 Ohm resistor?
a. it increases, b. it decreases, c. it doesn't change, d. it will be
less than the current in the 15 Ohm resistor.
PROBLEMS: SHOW WORK FOR EACH OF THE FOLLOWING. FULL CREDIT WILL NOT BE GIVEN
UNLESS WORK IS SHOWN. CIRCLE OR UNDERLINE ALL ANSWERS.
1.
A nichrome wire has a resistivity of 100 x 10-8 Ohm-meter. If a wire of
nichrome has a .04 square millimeter cross section.
How long would the
wire have to be to have a resistance of 10 Oms?
2.
Another nichrome wire has a length of 200 meters and draws 0.25 Amps of
current from a power supply. The voltage drop across this resistor is
100 Volts. Determine the resistance and cross-sectional area of the
wire.
3.
7 Ohms
___/\/\/\___
|
|
4 Ohms
6 Ohms
|
17 Ohms |
___/\/\/\___
___/\/\/\___
__|___/\/\/\___|____|
|
|
|
|
|
|
15 Ohms |___|
R
|_____
|
2 Ohms |
|___/\/\/\___|
|___/\/\/\___|
|___/\/\/\___|
If the total resistance of the circuit is 7.59 Ohms determine R.
4.
|
----------||-----------|
|
|
|
|
|
V1
V2
13 V |
-/\/\/\--/\/\/\--/\/\/\-'
40 Ohms 25 Ohms
R3
If the total resistance of this circuit is
130 Ohms, compute the total voltage, total
current, Resistance R, and the voltage drops
V1 and V2.
5.
If the equivalent resistance is 26.65 Ohms, What is the resistance of R2.
90 Ohms
___/\/\/\/\___
|
|
|
R2
|
|___/\/\/\/\___|
|
|
___|
160 Ohms
|____
|___/\/\/\/\___|
|
|
|
70 Ohms
|
|___/\/\/\/\___|
6.
|
----------------||-------------|
|
|
|
|
|
|
|
300 Ohms
|
|
____/\/\/\/\___
|
|
|
|
|
|
|
225 Ohms |
|
|________|____/\/\/\/\___|_______|
|
|
|
300 Ohms |
|____/\/\/\/\___|
If the total current of the circuit
is 9 amps, determine the potential
difference across the power supply
and the currents in each branch.
7.
Find the total resistance of this resistor network
7 Ohms
____/\/\/\/\____
4 Ohms
|
|
____/\/\/\/\_______|
|______
|
|
5 Ohms
|
|
|
|____/\/\/\/\____|
|
__|
|___
|
10 Ohm
|
|
____/\/\/\/\____
|
|
3 Ohms
|
|
|
|____/\/\/\/\_______|
|______|
|
10 Ohms
|
|____/\/\/\/\____|
8.
13 Ohms
15 Ohms
____/\/\/\/\____________/\/\/\/\___________
|
|
|
|
_|
|___
| |
|
|
| |
16 Ohms
R
|
|
| |______/\/\/\/\__________/\/\/\/\___________|
|
|
<--4 Volts-->
|
|
|
|
|
|
| 14 Volt battery
|
|____________________||___________________________|
||
|
a.
b.
c.
d.
e.
f.
g.
h.
i.
What
What
What
What
What
What
What
What
What
is
is
is
is
is
is
is
is
is
the
the
the
the
the
the
the
the
the
The voltage drop
across this circuit
is 14 Volts and the
voltage drop across
16 Ohm resistor is
4 Volts.
equivalent resistance of the 13 Ohm and 15 Ohm resistor?
voltage drop across the top branch?
current in the top branch?
voltage drop across the 13 Ohm resistor?
voltage drop across the 15 Ohm resistor?
voltage drop across resistor R?
current through the lower branch?
resistance of resistor R?
total current drawn by this circuit?