Final answer:
Null measurements are an accurate electrical measurement technique that avoids altering the circuit conditions. Factors limiting null measurement accuracy include resistance variations and temperature effects on resistance. However, modern digital devices improve accuracy by being more sensitive and providing closer-to-zero current states.
Step-by-step explanation:
Understanding Null Measurements in Electrical Circuits
Null measurements are a precise method for measuring current and voltage within circuits. By ensuring no current flows through the measurement device, we preserve the original circuit conditions. One limiting factor in accuracy is the inherent resistance in the wires and connections. Although difficult, minimizing resistance through careful materials choice can help. However, some resistance variance over time is unavoidable. Another consideration is temperature: as it fluctuates, so does resistance. Even with ideal materials, this can't be wholly negated.
Digital devices provide a significant accuracy improvement over traditional analog meters like galvanometers for null measurements. Their greater sensitivity enables measurements of much smaller currents, thus achieving precision closer to the true 'zero' current state.
Ultimately, in the context of zeroing transducers, null measurements can be affected by these factors. However, the advancements in technology and digital meters that utilize solid-state electronics enable higher accuracies than past methods, making routine rezeroing less necessary. With accuracies achievable up to one part in 106, modern devices ensure that any deviations or drift from baseline are inconsequential for most practical purposes.