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Difficulty: MediumSwitches and Relays

In an electromechanical relay, the normally closed (NC) contacts maintain electrical continuity and allow current to flow through the load circuit when the control coil is de-energized.

Answer: Answer

Answer

True
Relay contact states are defined relative to the de-energized (unpowered) coil condition. Normally Closed (NC) contacts are held shut by a mechanical return spring when the coil has no current, thereby maintaining a complete circuit and allowing current to pass.

Step-by-Step Solution

1
Identify the operating definition of 'normal' in relay terminology.
The normal state refers to the resting condition of the relay when no voltage or current is applied to the electromagnetic coil.
All contact designations (Normally Open and Normally Closed) are standardized based on the unpowered coil state.
2
Determine the physical contact position of Normally Closed (NC) contacts in the unpowered state.
The internal return spring holds the movable armature firmly against the NC contact terminal, forming a continuous electrical path.
Mechanical spring tension keeps the circuit closed until magnetic force from an energized coil pulls the armature away.
3
Evaluate circuit continuity and current flow capability.
Because the physical contacts touch, electrical continuity exists and current can flow through the load circuit.
Closed contacts provide a low-resistance path allowing electrical current to circulate.

Key Concept

Normally Closed (NC) vs. Normally Open (NO) Relay Contact States
Estimated Time:45s
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Topics

Switches and Relays

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