In electric appliances, the relationship between current and voltage depends on the specific appliance and its electrical components. The rule you are referring to, where current increases when applied voltage decreases, is known as Ohm's Law, which applies to resistive loads. Ohm's Law states that the current (I) flowing through a conductor is directly proportional to the voltage (V) applied across it and inversely proportional to the resistance (R) of the conductor:
I = V / R
So, if the voltage (V) decreases while the resistance (R) remains constant, the current (I) will increase. This relationship is relevant for resistive loads like heating elements, incandescent light bulbs, and other appliances where the primary load is resistance-based.
However, for appliances that use motors, such as induction motors, the relationship between current and voltage is more complex due to the nature of the motor's operation. Induction motors work based on electromagnetic induction, and their current draw is influenced by several factors, including the mechanical load, motor efficiency, and power factor.
When the voltage applied to an induction motor decreases, the current draw may not always increase directly as it would in a purely resistive load. In some cases, the motor may experience reduced performance, such as decreased torque or speed, rather than a significant increase in current draw.
The exact relationship between voltage and current in an induction motor depends on various factors, including the motor's design, the type of load it's driving, and the motor's operating conditions. To understand the specific behavior of an induction motor under different voltage conditions, detailed motor performance analysis and testing are required.
In summary, Ohm's Law applies to resistive loads, where a decrease in voltage leads to an increase in current, assuming the resistance remains constant. However, for appliances using motors like induction motors, the relationship between voltage and current can be more complex and is influenced by various factors beyond just the voltage applied.