Relays and Reed Switches Overview

What is the primary function of the hinged lever in a relay?

In a relay, what is the purpose of the electromagnet?

Which of these describes the key advantage of using a relay switch?

What is the 'pull-on current' in a relay, as mentioned in the text?

What is the fundamental difference between a relay and a reed switch, based on the content?

What does the fact that the text refers to the relay as a 'mechanical current amplifier' imply?

What does the diagram provided demonstrate about a car's starter motor circuit using a relay?

What material are the reeds in a reed switch made of, according to the provided text?

Relays

Relays are electromagnetic switches
Consist of an electromagnet, a hinged lever, and a pair of contacts
When no current flows, the contacts are separated
When a current flows, the electromagnet attracts the armature, bringing the contacts together
This completes the circuit and allows current to flow
Allow a low-voltage circuit to control a high-voltage circuit
Used as a mechanical current amplifier
Used as a level sensor
The current needed to activate a relay is called the pull-on current, and the smaller current required to release it is called the drop-off current
Examples of use include washing machines, cars, etc.

Advantages of Relays

One circuit can control another
Low-voltage circuits can control high-voltage circuits
Small current in input circuit can control large current in output
Can be used in mechanical current amplification and level sensing

Reed Switches

Consist of thin iron strips (reeds) inside a glass tube
Reeds are made of magnetic material
When a current flows in a coil, the magnetic field produces magnetization in the reeds, attracting their ends to opposite poles
Function like relay switches, with input current on terminals A and B and output circuit on terminals C and D

This quiz covers the fundamentals of relays and reed switches, exploring their components, mechanisms, and applications in circuits. Understand how these devices are used to control high-voltage circuits with low-voltage inputs and their advantages in various settings such as washing machines and cars.