A common type of switch used in elec-
trical equipment is the multiple-pole rotary
switch. In this switch, the rotary contact arm
can be connected to one side of an electrical
circuit and the contacts can connect to sever-
al other circuits. By turning the control knob,
any desired circuit configuration can be
used. Multiple switching operations can be
done by mounting several rotary switches
on one control shaft, Figure 4-15. Where
might a switch like this be used?
Quiz–Chapter 4
Write your answers to these questions on a
separate sheet of paper. Do not write in this
book.
Draw the circuit diagram for each of the
following problems and compute the unknown
quantities.
1. A circuit has an applied voltage of 100
volts and a resistance of 1000 ohms.
What is the current flowing in the
circuit?
2. A circuit that contains 100 ohms resis-
tance has a current of two amperes.
What is the applied voltage?
3. A circuit that contains 10,000 ohms of
resistance has a current of 100 mA.
What is the applied voltage?
4. A circuit has an applied voltage of
200 volts that causes a 50 mA current
to flow. What is the circuit resistance?
5. An applied voltage of 50 volts causes a
current of 2 amperes to flow. What is
the circuit resistance?
6. A voltage of 500 volts is applied to a
circuit that contains 100 ohms of resis-
tance. What is the current?
7. If applied voltage is 400 volts and
resistance is 20,000 ohms, what is the
value of I?
8. A meter indicates a current flow in a
circuit of 0.5 amp. The circuit resistance
is 500 ohms. What is the value of E?
9. What applied voltage will cause 500 mA
of current to flow through 500 ohms of
resistance?
10. What applied voltage will cause 10 mA
of current to flow through 1000 ohms
of resistance?
11. An electric appliance has a resistance
of 22 ohms. How much current will it
draw when connected to a 110 volt line?
12. A 110 volt house circuit is limited to
15 amperes by the fuse in the circuit.
The following appliances are connected
to the circuit. Compute the individual
currents for each appliance. What is the
total current flowing in the circuit? Will
the fuse permit this current to flow?
Appliance 1 draws 2 amperes.
Appliance 2 has a resistance of
40 ohms.
Appliance 3 has a resistance of
20 ohms.
Chapter 4 Ohm’s Law
41
Power
source
3-way
switch
number 1
3-way
switch
number 2
Figure 4-14.
A three-way switch circuit. The light is off.
Figure 4-15.
Multiple-pole rotary switch.