Increasing resistance in a circuit typically causes a decrease in current flow, according to Ohm’s Law (V = IR), where V is voltage, I is current, and R is resistance. If the circuit operates with a constant voltage source, increasing resistance will cause a proportionate increase in voltage across the resistor. This relationship ensures that the total voltage in the circuit remains consistent, with the increased resistance absorbing more voltage proportionally.
A varistor is a type of voltage-dependent resistor that exhibits a non-linear resistance characteristic. It is designed to protect circuits against transient voltage spikes and surges by changing its resistance in response to the applied voltage. Under normal operating conditions, a varistor has a high resistance. However, when a voltage spike occurs, the varistor’s resistance decreases sharply, diverting excessive current away from sensitive components and thereby protecting the circuit.
When resistance is increased in a series circuit, the voltage drop across the resistor also increases. This is because the total voltage supplied by the source is distributed among all components in series according to their resistances. As the resistance of a series resistor increases, it consumes more of the total voltage, resulting in a higher voltage drop across that resistor.
Increased resistance does not reduce the total voltage supplied by a source in a circuit. Instead, it redistributes the voltage across different components based on their resistances. A higher resistance component will have a larger voltage drop across it, while the total voltage remains constant according to the circuit’s power supply.
The resistance of a varistor depends on the specific type and manufacturer, as varistors are designed to have varying resistance characteristics depending on the applied voltage. Typically, varistors have high resistance under normal conditions and lower resistance when subjected to high voltage transients. The resistance can range from several ohms to hundreds of kiloohms, depending on the design and intended application of the varistor in protecting electronic circuits from voltage surges.