Is Voltage Inversely Proportional to Current? Answered!

Is Voltage Inversely Proportional to Current? Answered! |

Voltage has an essential role in any electric circuit; it’s why the particles move from one direction to the other. No circuit can operate without a voltage source; there will be no force to move the particles to operate the device. The same goes for the electric current because the voltage is responsible for its pressure, so is voltage inversely proportional to current?

Is Voltage Inversely Proportional to Current?

No, the voltage is not inversely proportional to the current; however, they can be inversely proportional in only one case. If the power is constant, the voltage and the current can be inversely proportional; the power formula is P= VI, so if you have a source of power that is 10 watts and another source of power that is 10 watts.

To increase the voltage and the power stays the same at 10 watts, the current has to decrease because the power is the total of multiplying the voltage and the current, so if one increases, the other has to decrease to keep the power constant. So this is the only case where the voltage can be inversely proportional to the current.

Ohm’s law is another way to show that voltage and the current are directly proportional; the voltage can be calculated in Ohm’s law through this equation V= IR. The voltage here is directly proportional to the current and constant resistance; on the contrary, the current is always inversely proportional to the resistance.

Is Voltage Inversely Proportional to Resistance?

No, the voltage is neither inversely proportional nor directly proportional to the resistance, the voltage doesn’t increase as the resistance increases, and the voltage always has a fixed value. So you can imagine the case here as it was a river; the voltage would be the pressure of the river’s water.

Meanwhile, the current will be the flowing water, and the resistance is a rock in the river path. The voltage or the pressure will stay the same regardless of the size of the rock in its path; the pressure stays the same. If the rock gets bigger, this won’t change the pressure of the water, even if it blocks the path.

The only thing that will get affected is the water passing, which is current; if the path is blocked, there will be no flow of water, but they will have the same pressure.

What Does Voltage Mean?

The voltage refers to the pressure that results from the power source; this pressure is used to push the current’s particles to move through a conductor, which is a work that is used to power up devices such as electric blubs. The voltage is measured in voltage V; the voltage can also be seen in the symbol E.

This is due to, in the beginning, the voltage was referred to as electromotive force (EMF); you can see this in early equations of electricity as Ohm’s law. If you have a simple circuit consisting of a lamp, wire, and battery, the voltage’s source will be the battery; there will be a potential difference between the battery’s poles.

What Is the Difference Between AC Voltage and DC Voltage?

The voltage can differ as the current differs; the current has two types which are alternating current “AC” and direct current “DC,” and each one has different features and uses, for example:

AC Voltage

  • It flows in waves
  • Its direction changes with time through constant intervals.
  • Generators are used to produce it through mechanical energy.
  • It varies from country to country; for example, the USA has 120 volts.
  • Many devices can’t use AC directly; a rectifier has to be used to convert it to a DC.

DC Voltage

  • It has only one direction, which doesn’t change with time.
  • Batteries are used to generate direct currents.
  • DC sources have poles which means that they have polarity.
  • Used in portable devices such as flashlights, cameras, and remote controllers.

Are Voltage and Potential Difference The Same Thing?

Yes, they refer to the same thing: the multiplication of resistance with the electric current. The two terms are used interchangeably; however, potential difference refers to the difference between two points in an electric circuit. The difference between the two points shows how much work or volt is needed.

For example, if you want a small number of volts, you can use an alkaline battery, generating 1.5 volts. However, big devices in households need a more considerable number, so the power source in houses could be 120 or 220-240 volts.

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Is Current Inversely Proportional to Resistance?

Yes, the current is inversely proportional to resistance; increasing the resistance will decrease the current; however, increasing the current doesn’t decrease the resistance. You can imagine it as a road full of cars, and the road has obstacles in it; when the obstacles increase, the cars will be affected.

But when you increase the number of cars, this doesn’t affect the obstacles. Another way to explain the case is that electricity can be imagined as a river, the water is current, and the rocks in the river are the resistance. Increasing the water doesn’t affect the rocks; their number will stay the same; however, increasing the rocks affect the water passing through.

What Are The Factors That Affect The Resistance?

The resistance isn’t affected by either current or voltage; however, the resistance can still be affected by four factors: the wire’s length, the wire’s cross-sectional area, temperature, and the material’s nature. This can be seen in the resistance formula R= ρ*L/A.

Where ρ stands for resistivity, which depends on the material’s nature, L refers to the wire’s length, and A stands for the wire’s cross-sectional area.

  • The Wire’s Length
    It increases the resistance because the current takes more time to overcome the resistance; therefore, the long wires have more resistance than the short wires.
  • The Wire’s Cross-sectional Area
    It decreases the resistance because the larger the area is, the more room the current has to pass through; when the wire has a small cross-sectional area, the current particles have less space to move, so they collide with each other, the resistance increases.
  • The Resistivity
    The resistivity depends on the nature of the wire’s material; each material has a specific resistivity; for example, the copper has a 1.72 x 10-8 Ωm resistivity, while silver has a 1.59 x10-8 Ωm resistivity.
  • The Temperature
    It increases the resistance when the wire’s temperature increases; this gives the particles of the current more kinetic energy, so they start to collide; therefore, energy increases.

How To Decrease Wire’s Resistance?

The main factors which affect the resistance are the wire’s length, the wire’s cross-sectional area, temperature, and the material’s nature, and you can decrease the resistance of a wire only through them. For example:

    • Material’s Nature
      You can change the wire’s material to another material with a smaller resistivity.
    • Wire’s Length
      You can use shorter wires, as they have much less resistance than the long ones.
    • Wire’s Cross-sectional Area
      You can use wires with larger cross-sectional areas, “thicker wires,” as they have much less resistance than those with small cross-sectional areas, “thin wires.”
    • Temperature
      You can try lowering the temperature, the more high the temperature, the more wire resistance.


To sum up, voltage and current are not inversely proportional except in one case, which is when the power is constant; if you increase the current, the voltage needs to be decreased to have constant power, and if you increase the voltage, the current needs to be decreased to have constant power.

On the contrary, voltage and current are directly proportional in many other cases; for example, in Ohm’s law, if you have a constant resistance increasing the current will increase the voltage, and increasing the voltage will increase the current. However, it’s different regarding the relation between voltage and resistance.

The voltage doesn’t get affected by the resistance, and the resistance doesn’t get affected by the voltage. So the voltage has a fixed value even if you have increased the resistance because the voltage is the pressure of the current, so the pressure stays the same, but the current intensity is the one that gets affected.

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