Electrical Components Chapter 3

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Questions and Answers

What indicates that a switch may be faulty when tested in a circuit?

The switch will illuminate without power.

The switch is warm to the touch when powered.

The switch emits a clicking sound when activated.

The light does not turn on but illuminates when bypassed with a jumper wire. (correct)

Which method would NOT be appropriate to test a switch in a circuit?

Using a jumper wire to bypass the switch.

Testing voltage drop across the switch.

Measuring resistance for continuity.

Observing the physical state of the switch. (correct)

Which factor does NOT affect the strength of an electromagnet?

The color of the wire used for winding. (correct)

The size and length of core material.

The amount of current flowing through the wire.

The number of windings in the coil.

In what scenario would testing for continuity be relevant in an electrical setup?

To check if an open circuit exists. Signup and view all the answers

What is the primary function of a relay in a car's electrical system?

To control high current devices safely. Signup and view all the answers

What is the primary reason a fuse blows in a vehicle?

Too much current Signup and view all the answers

How can you visually inspect a cartridge fuse to check if it is blown?

Pull it out for a visual inspection Signup and view all the answers

What characteristic defines a circuit breaker compared to a fuse?

It can reset itself after tripping Signup and view all the answers

What is the function of a fusible link in a circuit?

Burns up before the main circuit wiring Signup and view all the answers

What type of switch is known as the most basic form of switch?

Single Pole Single Throw (SPST) Switch Signup and view all the answers

What is the best way to test if a switch is functioning properly?

By ensuring power goes in and comes out. Signup and view all the answers

When checking fuses, what is the first step that should be taken?

Make sure ignition is on for circuit voltage Signup and view all the answers

What may indicate that switch contacts are burnt?

No voltage output Signup and view all the answers

What is the primary function of a relay's electromagnetic coil?

To create magnetism and pull the switch closed Signup and view all the answers

What happens when terminal 87 is energized?

It has continuity with terminal 30 Signup and view all the answers

Which of the following is a difference between a 4 terminal relay and a 5 terminal relay?

4 terminal relays lack terminal 87a Signup and view all the answers

What is the potential consequence of jumping low current coil terminals?

Failure of the load to energize Signup and view all the answers

How can you determine the resistance value for a fixed resistor?

Using color bands and knowing their coding Signup and view all the answers

What effect does a stepped resistor have in blower motor circuits?

It alters the current flow to decrease speed Signup and view all the answers

What is a characteristic feature of a variable resistor like a rheostat?

It can physically change its resistance Signup and view all the answers

What is the primary function of a standard diode?

To allow current to flow in one direction only Signup and view all the answers

What may occur if the relay does not energize while a blower motor is set to high speed?

The blower motor will not operate Signup and view all the answers

Which type of transistor requires a positive voltage to turn on its base?

NPN transistor Signup and view all the answers

What is a common use for a potentiometer?

To control the brightness of dash lights Signup and view all the answers

In an LED, what happens when a forward voltage is applied?

The LED emits light Signup and view all the answers

How do capacitors function in electronic circuits?

By storing and rapidly discharging energy Signup and view all the answers

What primarily distinguishes a PNP transistor from an NPN transistor?

The voltage required to activate the base Signup and view all the answers

What role does a clamping resistor play in a circuit?

It dissipates voltage spikes Signup and view all the answers

What occurs when the positive terminal of a battery is connected to the positive terminal of a speaker?

The speaker moves outward Signup and view all the answers

Study Notes

Circuit Protection Devices

Fuses, circuit breakers, and fusible links are essential for protecting electrical circuits in vehicles.
Standard fuses have evolved to mini fuses due to space and efficiency considerations.

Fuse Functionality

Fuses blow primarily due to excessive current, which generates heat leading to failure.
To check if fuses are operational, use a test light to ensure power is present on both sides of the fuse.

Checking Fuses

Power should be verified at both ends of the fuse; the ignition must be on for circuits requiring voltage.
Some fuses may act as spares and show no power.
Cartridge fuses may need removal for visual inspection to confirm failure, as test lights may not be applicable.

Circuit Breakers

Circuit breakers trip like fuses but can reset automatically after cooling down.
A functioning circuit breaker will display a small amount of resistance.

Fusible Links

These are specially designed wires that burn out before the circuit wiring, acting as an extra layer of protection.
Testing involves physically pulling them to identify damage.

Switches

Various types of switches control current flow in vehicles, generally designed to open or close circuits.
SPST (Single Pole Single Throw) is the simplest switch type, while SPDT (Single Pole Double Throw) and DPDT (Double Pole Double Throw) enable more complex functionalities.

Switch Operation

Internal contacts need to be periodically inspected for damage.
Hood and trunk light switches may use mercury or a metal ball to operate.

Testing Switches

The best practice is to check for power input and output; if voltage does not transmit through a switch, it may be defective.
Resistance can be measured to ascertain continuity.

Circuit Construction

Basic circuits can be created using switches and light bulbs, while thorough testing can confirm their functionality.

Electromagnets

Formed when current flows through coiled wires; strength is influenced by current amount, coil windings, and core size.
Used in car relays that operate high-current components like fuel pumps and cooling fans.

Relays

These electromagnetic switches manage high amp draw devices while protecting the activating switch.
Standardized terminals (e.g., 85, 86, 30, 87, 87A) designate functional connections.

Fixed Resistors

Introduce resistance into circuits, decreasing current flow, and are commonly found in circuit boards.
Color bands on resistors help identify resistance values.

Stepped Resistors

Typically found in blower motor circuits to control fan speed; malfunctioning resistors affect operation.

Variable Resistors

Includes rheostats and potentiometers, allowing for adjustments in resistance and found in devices like dimmer switches and throttle position sensors.

Diodes

Act as one-way electrical check valves, allowing current flow in only one direction.
LEDs (Light Emitting Diodes) function similarly, producing light when current flows properly.

Transistors

Serve as high-speed electrical switches with a tri-leg setup (emitter, base, collector).
Differences between PNP and NPN transistors lie in the voltage required to activate their bases.

Capacitors

Function as rapid charge/discharge devices, useful for storing energy, timing applications, and noise filtering.

Speaker Functionality

Based on the interaction between an electromagnet and a permanent magnet, producing sound.
Proper polarity connection is necessary for correct speaker operation.

Summary

Knowledge of electrical components, their testing methods, and applications ensures safe and effective vehicle maintenance and repairs.

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Description

Explore the essential circuit protection devices in Chapter 3 of Electrical Components. This quiz covers fuses, circuit breakers, and fusible links, aiming to deepen your understanding of why these components are critical in preventing electrical failures. Test your knowledge on why fuses blow and how resistance, voltage, and current contribute to their operation.