Understand Ohm's Law for Mohm Resistors

Introduction

Ohm's Law provides a fundamental understanding of electrical circuits, describing the relationship between voltage, current, and resistance. When it comes to resistors with extremely high resistances (in the megohm range), it becomes crucial to understand how Ohm's Law applies specifically to these Mohm resistors.

Ohm's Law for Mohm Resistors

Ohm's Law states that the current (I) flowing through a resistor is directly proportional to the voltage (V) applied across it and inversely proportional to the resistance (R):

I = V / R

For Mohm resistors, the resistance values are significantly higher than for typical resistors, typically ranging from one million ohms (1 Mohm) to several gigohms (10^9 ohms). This means that even small changes in voltage can result in significant changes in current.

Table 1: Typical Resistance Values for Mohm Resistors

Applications of Mohm Resistors

Mohm resistors find applications in various electronic circuits, including:

• Voltage dividers
• High-impedance sensors
• Amplifiers
• Precision instruments

Pain Points

Using Mohm resistors can encounter certain pain points:

• High sensitivity: Small voltage variations can lead to large current changes, requiring precise voltage control.
• Parasitic capacitance: Mohm resistors can exhibit parasitic capacitance, which can affect circuit performance at high frequencies.

Motivations

The motivations for using Mohm resistors include:

• High impedance: Mohm resistors provide very high impedance, isolating circuits from unwanted currents.
• Precision: Mohm resistors offer high precision in applications requiring accurate voltage and current measurements.

Tips and Tricks

• Use low-noise power supplies: To ensure precise voltage control, use power supplies with low noise levels.
• Consider parasitic capacitance: Account for parasitic capacitance when designing circuits using Mohm resistors, especially at high frequencies.
• Choose appropriate resistors: Select Mohm resistors with suitable resistance values and tolerances based on the specific circuit requirements.

Step-by-Step Approach to Using Mohm Resistors

1. Determine the required resistance value based on the circuit design.
2. Choose a Mohm resistor with the appropriate resistance and tolerance.
3. Mount the resistor securely in the circuit.
4. Verify the circuit's performance by measuring voltage, current, and resistance values.

Conclusion

Understanding Ohm's Law is crucial when working with Mohm resistors. Their high resistance requires careful consideration of voltage changes and parasitic capacitance. By addressing these pain points and following the tips and tricks, engineers can effectively utilize Mohm resistors in various electronic circuits, harnessing their high impedance and precision.