Question

what symbol would best represent an electric fan speed controller in an electric circuit?

Explanation:

1. Analyze each symbol:

• The first symbol (switch - open) represents a switch, not a speed controller.
• The second symbol (light bulb) represents a load like a bulb, not a speed controller.
• The third symbol (resistor - zig - zag) can represent a variable resistor or a component that controls current (which is what a fan speed controller does, as it adjusts resistance to change speed).
• The fourth symbol (battery) represents a power source, not a speed controller.

1. Conclusion: The zig - zag resistor - like symbol is the one that best represents a fan speed controller as it can act as a variable resistor to control current (and thus speed) in the circuit.

Answer:

The third symbol (the zig - zag resistor - like symbol, \(\sim \!\!\!\!\!\! \text{W}\!\!\!\!\!\! \sim\))