TUTORIAL QUESTIONS
1. With a well annotated diagram to illustrate how it works, explain the term switches.
2. List the three main classes of switches and do the following:
a. Give brief explanations with examples of the three classes of switches
b. Mention ten (10) advantages of each of the three classes of switches
c. Mention ten (10) disadvantages of each of the three classes of switches
3. Explain the following terms as it relates to mechanical switches:
a. The POLE of a mechanical switch.
b. The THROW of a mechanical switch
4. Based on the number of POLES and THROWS, draw and explain the workings of a
complete circuit that applies the following types of switches to do anything of your
choice
a. Single Pole Single Throw Switch (SPST)
b. Single Pole Double Throw Switch (SPDT)
c. Double Pole Single Throw Switch (DPST)
d. Double Pole Double Throw Switch (DPDT)
e. The Push Button Switch
5. With well-labelled diagrams give concise explanations of the workings and use of the
under listed electronic devices as switches in any application of your choice.
a. The Bipolar Junction Transistor (BJT)
b. The Metal Oxide Semiconductor Field Effect Transistor (MOSFET)
c. The Silicon Controlled Rectifier (SCR)
d. The Diode
e. The Thyristor
6. Explain with clearly labelled diagrams the following terms as far as switches are
concerned;
a. “Normally Open”
b. “Common”
c. “Normally Closed”
7. Elucidate the workings of an Electromechanical Relay. Ensure that a well-labelled
diagram is used for the explanation.
8. Give Eight (8) advantages and eight (8) disadvantages of Electromechanical Relays.
9. Elucidate the workings of a Solid State Relay with a well annotated diagram.
10. Give Eight (8) advantages and eight (8) disadvantages of Solid State Relays.
11. What is a Contactor? Explain how a Contactor works with a well-illustrated diagram.
12. Explain in details the need for CONTACTORS.
13. What is the benefit of auxiliary contact?
14. How will you power an 18V, 3amps motor with a 5V, 0.3amps transistor?
NOTE: All circuit components must be well-labelled and all line currents and voltages
highlighted.
15. Using a cascade of exactly three relays, use an 18V, 0.3A power source to switch on a
240V, 13A fan.
NOTE: All circuit components must be well-labelled and all line currents and voltages
highlighted.
16. When the voltage available to power a relay circuit is more than what the relay
circuit needs, what needs to be done to enable the use of the excessive voltage
source to power the relay? ASSUME: Voltage source: 9V; Relay Voltage: 6V.
17. What would happen when the available power to a relay circuit is less than what the
relay circuit needs? ASSUME: Voltage source = 3V; Relay Voltage = 6V.