What are the characteristics of conductors?
- Allow easy electron movement
- Examples: copper, aluminum, silver, gold
Conductors facilitate the flow of electrical current.
What are the characteristics of insulators?
- High resistance
- Block current flow
- Can store charge
- Examples: rubber, plastics, glass
Insulators prevent the flow of electrical current.
What are semiconductors?
- Have properties between conductors and insulators
- Example: silicon
Semiconductors are used in various electronic components.
According to the 1-10-100 rule, what happens at 1 mA?
Felt
This rule describes the effects of electrical current on the human body.
According to the 1-10-100 rule, what happens at 10 mA?
Causes muscle contraction
This rule highlights the dangers of electrical currents.
According to the 1-10-100 rule, what happens at 100 mA?
Can be fatal
This emphasizes the lethal potential of electrical currents.
What is the function of a switch in an electrical circuit?
Controls the flow of electrical current
A switch can open (off) or close (on) a circuit.
What is the resistance of a closed switch?
Nearly zero resistance
Closed switches allow current to flow freely.
What is the resistance of an open switch?
Near-infinite resistance
Open switches prevent current from flowing.
Name the types of switches classified by poles and throws.
- Single-pole, single-throw (SPST)
- Single-pole, double-throw (SPDT)
- Double-pole, single-throw (DPST)
- Double-pole, double-throw (DPDT)
These classifications determine how switches operate in circuits.
What is the purpose of a fuse in a circuit?
Protects circuits from overloads
A fuse melts to break the circuit if excessive current flows.
What components are needed for a complete DC circuit?
- Power source
- Closed switch
- Load (like a lamp)
- Conductors (e.g., copper wires)
These components allow current flow in a circuit.
What is the effect of insulators in a circuit?
Do not allow current to flow
Insulators cannot complete a circuit.
When measuring resistance with a multimeter, how should you hold the probes?
By their insulation, not the metal tips
Touching the metal can affect the accuracy of the measurement.
What should you do to measure your body resistance accurately?
- Loosely hold the probes
- Reverse the ohmmeter leads
- Increase grip
- Wet your thumb and finger
These methods help in obtaining accurate resistance readings.
How many connecting terminals does an SPDT switch have?
3
SPDT switches allow switching between two different circuits.
Which switch can reverse the polarity of a circuit?
DPDT
This switch is useful for controlling motor direction.
What is the voltage drop across a closed switch?
0 V
A closed switch does not impede current flow.
What is the expected resistance of an open (blown) fuse?
Infinite Ω
A blown fuse does not allow current to pass.
