Difference between Voltage and Voltage Drop

A battery produces a voltage by converting chemical energy into electrical energy. This battery (or voltage source) provides the energy required to move the charge. Components such as resistors consume some energy while current flows and the voltage drop of a component is the amount of work per unit charge connected with the current running through it. A fraction of the voltage generated by the battery is accounted for by the voltage absorbed by a component. In other ways, the work done by the battery power source is distributed throughout the circuit’s components.

What is Voltage?

The voltage is defined as the difference in potential energy between two locations in a circuit. A voltage or potential difference is the difference in charge between higher and lower potentials. 

The electrons are compelled to flow across the circuit by the voltage or potential difference. The potential of one point is greater than the potential of the other point.  It is measured in volts and maybe measured with a voltmeter. The greater the force, the more electrons travel across the circuit, and hence the higher the voltage. Electrons would travel randomly in open space if there was no voltage or potential difference. The current is proportional to the voltage. Larger electrical appliances require greater voltage and current than smaller appliances. for example, the voltage can come from the power plant, battery, etc.

Now look into this dc circuit,

Voltage causing the bulb to glow

Here battery (V) is the voltage, the current flow to the bulb to glow and reaches back to the power source.

Voltage drop

The difference in potential over any two points is known as voltage drop. Here the voltage source is greater than the voltage drop. We can say that voltage is split across the components (like passive components or others) connected in the loop. This drop might be induced by a resistor, capacitor, or inductor (in AC), or it could be caused by anything else too. The voltage loss is proportional to the resistance, according to the ohms law.

The voltage drop formula is given by the Ohm’s law as,

V = R × I

where,

• V is the voltage drop (in Volts),
• R is the resistance (in Ohms), and
• I is the current (in Amps).

Example for voltage drop

Here in the circuit, the battery (V) is the voltage or power source, V₁ is the voltage drop across R₁, V₂ is the voltage drop across R₂ and V₃ is the voltage drop across R₃.

Difference between Voltage and voltage drop

Voltage	Voltage Drop
Voltage is nothing but potential difference.	Voltage drop is derivated from voltage.
It is nothing but producing voltage.	It is nothing but a loss in voltage.
Summing all the voltage drops  makes a voltage.	Voltage drop is not a total voltage  but a part of the voltage.
Voltage is a power source, the element is active (its own voltage).	Here voltage drop is some other voltage  created by an external source. The elements like a (passive) resistor, capacitor, etc.
This can have a voltage without the flow of current.	This cannot have a voltage drop without the flow of  current.
It is a force that makes electrons move  in a circuit.	Voltage is generated through current passing in a component.
The unit for voltage is Volt.	The unit for voltage drop is also Volt.

Sample Questions

Question 1: If a current of 12 A is flowing through a circuit that has a resistor of 8 ohms, calculate the total voltage.

Answer:

Given that,

Current (I) = 12 A,

Resistor (R) = 8 ohms.

Now, using the formula,

V = I × R

= 12 × 8

= 96 V

Question 2: What is the current flowing through the resistor 30 ohms, if the voltage is 60 V and 120 V?

Answer:

Given that,

For case I:

V = 60 V

R = 30 ohms

Therefore, using the formula:

V = I R

or 

I = V/R

= 60/30

= 2 A

Now, for case II:

V = 120 V

R = 30 ohms 

I = V/R

= 120/30

= 4 A

Question 3: Calculate the voltage drop V₃ across the R₃ resistor, If the voltage is 120 volts and R₁ is 12 ohms, R₂ is 5 ohms, R₃ is 8 ohms

circuit problem

Answer:

Given that,

V = 120 volts 

R₁ =12 ohms

R₂ = 5 ohms

R₃ = 8 ohms

Using the formula, lets determine the equivalent resistance:

R = R₁ + R₂ + R₃ 

=12 + 5 + 8

= 25 ohms

Now, from the formula, 

I = V/R

= 120/25

= 4.8 A

So voltage drop across R₃ is,

V₃ = R₃ × I

= 8 × 4.8 

= 38.4 V

Question 4: Calculate the total voltage from the given circuit if R₁ is 2 ohms, R₂ is 4 ohms, R₃ is 12 ohms and current I is 34 A.

Given Circuit 

Answer:

Given that,

R₁ = 2 ohms

R₂ = 4 ohms

R₃ = 12 ohms

I = 34 A

To find R,

1/R = 1/R₁ + 1/R₂ + 1/R₃

= 1/2 + 1/ 4 + 1/ 12

= 5/6

or

R = 6/5 

R = 1.2 ohms 

Now to find V,

V = I × R

= 34 × 1.2

= 40.8 V

Question 5: Calculate the value of the resistance, if the voltage across the circuit is 27 V and the current flowing through it is 3 mA. 

Answer:

Given,

Voltage  V  = 27 V

Current  I = 3 × 10^-3 A

Resistance R = ?

from formula , V = I × R

R = V/I

= 27 / 3 × 10^-3

= 9 ×10³ ohms