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Loading Effect Explained In 2 Minutes !!

posted Jul 31, 2017, 12:12 PM by Rohit Bhaskar

​Before we start, let me clarify that this post is on loading effect in electronic circuits and not loading effects given to web pages (hmm.. seems like another good future topic ;p )

2 things are included included in loading effect. One is that a load (measuring instrument) takes power from its own circuit and other that the load has a resistance of its own, which affects overall resistance of the circuit. (Series or parallel resistance)

  1. Loading Effect hugely affects Electrical Measuring Instruments. A Measuring Instrument is supposed to measure a particular quantity without drawing any power from the system in which it measures. However, in most of the analog measurements, the Instrument does draw some power without which it cannot measure the quantity. An example is a shunt connected voltmeter draws some current to measure the voltage. Hence some additional power is drawn from the supply.
  2. When a load circuit having low effective impedance is connected to a supply circuit having higher effective impedance. This happens because the net parallel resistance is lower than any individual resistors making up the parallel combination. So on connecting the load circuit effective reduces the resistance, drawing more (load) current causing greater voltage drop in the supply circuit.

This can be eliminated if the load resistance is much greater than the source resistance. So ideally buffers would totally eliminate loading (we will cover buffers in a future post 😉 )

That’s all for today, though this was a short post!