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An automatic electric iron use Electromagnet relay
True
False
False
An automatic electric iron does not use an electromagnetic relay for temperature control; instead, it uses a bimetallic strip thermostat. The bimetallic strip acts as a mechanical switch that opens or closes the circuit based on thermal expansion rather than electromagnetic force.
An automatic electric iron does not use an electromagnetic relay for temperature control; instead, it uses a bimetallic strip thermostat. The bimetallic strip acts as a mechanical switch that opens or closes the circuit based on thermal expansion rather than electromagnetic force.
╬ФL=L0тАЛ╬▒╬ФT тАФ representing the thermal expansion principle governing bimetallic operation
The bimetallic strip consists of two dissimilar metals with different coefficients of thermal expansion bonded together. When the heating element reaches the set temperature, the strip bends due to unequal expansion, physically breaking the contact and cutting off the power. As the plate cools, the strip returns to its original position, reconnecting the circuit.
Electric irons utilize a bimetallic strip thermostat for temperature regulation.
Bimetallic strips rely on the difference in the coefficient of thermal expansion (╬▒) of two metals.
Electromagnetic relays are typically used in motor starters, protection circuits, or high-voltage switching, not in resistive household heating appliances like irons.
The temperature setting in an iron varies the physical gap the bimetallic strip must bridge to disconnect the heating element.
Simple mechanical construction
Reliable and low cost
Does not require a separate control power source
Subject to mechanical wear and fatigue over time
Hysteresis causes temperature fluctuations around the set point
Electric Irons
Toasters
Water Heaters (Geysers)
Coffee Makers
The bimetallic thermostat converts thermal energy directly into mechanical movement.
Option A is incorrect because the iron uses a thermal switch, not an electromagnetic relay which requires a solenoid coil and magnetic flux linkage.
B is correct тАФ An automatic electric iron uses a bimetallic strip thermostat, not an electromagnetic relay, to regulate temperature via thermal expansion.
In competitive exams, remember that resistive household appliances (toasters, irons) use 'thermal' sensing, whereas industrial motors/heavy equipment often use 'electromagnetic' sensing.