In a simple definition, the Voltage drop in an electrical or electronic circuit is the lowering or decreasing of electric potential along with the path of the flow of electric current in that circuit. There is no practical electrical or electronic circuit where voltage drop does not occur. In all the closed electrical or electronic circuits, a voltage drop occurs.

Here is the list of places where voltage drop occurs,

• Internal Resistance of the Power Source
• Across current-carrying conductors
• Across electrical contacts
• Across electrical or electronic components
• Across connectors

Causes of Voltage Drop

Resistance and the flow of current, both are the main responsible factors for voltage drop.

1. Voltage Drop in the Power Source

An ideal power source has no internal resistance but a practical power source has internal resistance. So, when a load is connected to the power source current starts flowing from the power source to the load through the internal resistance. So, as the current flows through the internal resistance, it also creates a voltage drop.

2. Voltage Drop across Conductors

Generally, all the wires or electrical conductors have internal resistance depending upon the properties of the manufacturing material. So when those conductors conduct current, a voltage drop will occur due to their internal resistance.

3. Voltage Drop across Electrical Contacts

Voltage drop occurs in an electrical contact due to the contact resistance. This contact resistance depends upon the size of contacts, area of the contact point, properties of contact material, strength or tightness of the contact, etc.

4. Voltage Drop across components

Almost all the electrical or electronic components have an internal resistance that is constant. So, due to that, a constant voltage drop occurs when they are connected in a circuit. Also, resistance property changes in some components due to the nature of the flowing current, frequency, etc. So, for those variable voltage drops occurs.

5. Voltage Drop across the Load

Electrical loads are those that actually consume electrical power. An electrical load only makes a higher voltage drop. This depends upon the internal resistance of the load and the current consumed by the load.

Voltage Drop Formula and Calculation

The formula for voltage drop is very simple. If you don't know the internal resistance of the circuit then the voltage drop can be calculated by subtracting the receiving end voltage from the sending end voltage.

So, the voltage drop Vd = Vs-Vr

Let's understand with a circuit example.

No, if we calculate the voltage drop,

Effects of Voltage Drop

1. Voltage Drop causes to decrease or reduction in the voltage from the actual source voltage to load voltage.

2. Voltage drop causes to decrease in the flow of electric current also.

3. Voltage drop produces power loss in the circuit, or it wastes electrical energy.

4. Voltage drop can step down both AC and DC voltage.

5. Voltage drop makes the circuit less efficient.

Applications and examples Voltage Drop

1. Rheostat works on the principle of voltage drop. It steps down voltage by dropping the voltage.

2. Old or conventional electrical fan regulator also works on the principle of voltage drop. It varies voltage across the ceiling fan coil and the flow of current by varying the voltage drop in its variable resistor.

3. Transformerless power supply with series capacitor also works on the principle of voltage drop but here the voltage drop happens due to the capacitive reactance, not resistance.