Three components of a relay

1. Coil: The coil is an electromagnetic component that generates a magnetic field when voltage is applied. This magnetic field is used to activate the relay's contacts.

2. Contacts: The contacts are the switch-like components inside the relay that open or close when the coil is activated. These contacts are used to control the flow of current in a circuit.

3. Housing: The housing or casing of the relay is the outer covering that protects the internal components from damage and environmental factors. It also provides a means for mounting the relay securely in place.