How does Ohm's Law apply to variable resistors and potentiometers?
1 Answer
Ohm's Law is a fundamental principle in electrical circuits that relates three key electrical variables: voltage (V), current (I), and resistance (R). It states that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them. Mathematically, Ohm's Law is expressed as:
V = I * R
Where:
V = Voltage (measured in volts, V)
I = Current (measured in amperes, A)
R = Resistance (measured in ohms, Ω)
Now, when it comes to variable resistors and potentiometers, Ohm's Law still applies, but with some considerations due to their variable nature.
Variable Resistors (Rheostats):
A variable resistor, also known as a rheostat, is a two-terminal passive electronic component whose resistance can be adjusted to control the current flow through a circuit. The resistance of a variable resistor can be changed by physically moving a slider or rotating a knob.
Ohm's Law applies to variable resistors just like it does to fixed resistors. The current flowing through the variable resistor is directly proportional to the voltage across it and inversely proportional to the resistance setting. If you increase the resistance, the current will decrease for a given voltage, and vice versa.
Potentiometers:
A potentiometer (pot) is a three-terminal variable resistor with an adjustable voltage divider. It has a resistive track across which a wiper moves, allowing the voltage output to be varied between the two outer terminals.
In the context of a potentiometer, Ohm's Law applies not only to the overall resistance but also to the voltage output across the wiper terminals. The voltage output (V_out) is determined by the position of the wiper along the resistive track and the input voltage (V_in). The relationship between the output voltage and the input voltage and resistance is given by:
V_out = (R_wiper / R_total) * V_in
Where:
R_wiper = Resistance between the wiper and one of the outer terminals (variable)
R_total = Total resistance of the potentiometer (constant)
V_in = Input voltage
So, in this case, the output voltage is directly proportional to the position of the wiper (variable resistance) and the input voltage, and inversely proportional to the total resistance.
Keep in mind that for some specialized potentiometers, the resistance between the wiper and one of the outer terminals may not be linear, leading to non-linear relationships between the wiper position and output voltage. However, for most standard potentiometers, the resistance track is linear, and Ohm's Law can be applied as described above.
V = I * R
Where:
V = Voltage (measured in volts, V)
I = Current (measured in amperes, A)
R = Resistance (measured in ohms, Ω)
Now, when it comes to variable resistors and potentiometers, Ohm's Law still applies, but with some considerations due to their variable nature.
Variable Resistors (Rheostats):
A variable resistor, also known as a rheostat, is a two-terminal passive electronic component whose resistance can be adjusted to control the current flow through a circuit. The resistance of a variable resistor can be changed by physically moving a slider or rotating a knob.
Ohm's Law applies to variable resistors just like it does to fixed resistors. The current flowing through the variable resistor is directly proportional to the voltage across it and inversely proportional to the resistance setting. If you increase the resistance, the current will decrease for a given voltage, and vice versa.
Potentiometers:
A potentiometer (pot) is a three-terminal variable resistor with an adjustable voltage divider. It has a resistive track across which a wiper moves, allowing the voltage output to be varied between the two outer terminals.
In the context of a potentiometer, Ohm's Law applies not only to the overall resistance but also to the voltage output across the wiper terminals. The voltage output (V_out) is determined by the position of the wiper along the resistive track and the input voltage (V_in). The relationship between the output voltage and the input voltage and resistance is given by:
V_out = (R_wiper / R_total) * V_in
Where:
R_wiper = Resistance between the wiper and one of the outer terminals (variable)
R_total = Total resistance of the potentiometer (constant)
V_in = Input voltage
So, in this case, the output voltage is directly proportional to the position of the wiper (variable resistance) and the input voltage, and inversely proportional to the total resistance.
Keep in mind that for some specialized potentiometers, the resistance between the wiper and one of the outer terminals may not be linear, leading to non-linear relationships between the wiper position and output voltage. However, for most standard potentiometers, the resistance track is linear, and Ohm's Law can be applied as described above.