According to Ohm’s law,

Mathematically it can be represented as,

**Potential difference ∝ Current**

**V ∝ I ** (So when the value of V increases then the value of I also increases simultaneously)

V = IR

Where,

V is Voltage in volts (V)

R is Resistance in ohm (Ω)

I is Current in Ampere (A)

__Formulae:__

- To find Voltage(V),

**V = IR**

- To find Current(I),

\(I=\frac{V}{R}\)

- To find Resistance(R),

\(R=\frac{V}{I}\)

**V I R**triangle can be used to calculate all formulations of ohm’s law.

#### Ohm’s Law Magic Triangle:

The triangle for Ohm’s law is

- If the value of Voltage is asked and the values of the current and resistance are given, then to calculate voltage simply cover the We are left with the
**I**and**R**or**I X R**. So, the equation for Voltage is Current multiplied by Resistance.

**Example 1:**If resistance of an electric iron is 50Ω and 3.2A Current flows through the resistance. Find the voltage between two points.

**Ans. **Given,

Resistance (R) = 50Ω

Therefore, Voltage (V) = I X R

= 3.2A x 50 Ω

=160V

- If the value of Resistance is asked and the values of the current and voltage are given, then to calculate resistance simply cover the
**R**, we are left with the**V**at the top and**I**to the bottom left or**V ÷ I**.

**Example 2:**An EMF source of 8.0 V is connected to a purely resistive electrical appliance (a light bulb). An electric current of 2.0 A flows through it. Consider the conducting wires to be resistance free. Calculate the resistance offered by the electrical appliance.

**Ans. **Given,

Voltage (V) = 8.0 V

Current (I) = 2.0 A

Therefore, Resistance (R) = V ÷ I = \(\frac{V}{I}\)

= \(\frac{8}{2} = 4\)

- If the value of current is asked and the values of the resistance and voltage are given, then to calculate current simply cover the
**I**. We are left with Voltage over Resistance or**V ÷ R**. So the equation for Current is Voltage divided by Resistance.

**Example 3:**If the filament resistance of an electric bulb is 330 Ω and Potential difference of two points 110V. Find the current flowing through the filament.

**Ans. **Given,

Resistance (R) = 330 Ω

Voltage (V) = 110V

Therefore, Current (I) = V ÷ R = \(\frac{V}{R}\)

= \(\frac{330}{110} = 3A\)

### Calculation of Electrical Power:

The electrical power can be calculated using the Ohm’s law and by substituting the values of voltage, current and resistance.

__Formulae to find power:__

- When the values for voltage and current are given,

**P = V X I**

- When the values for voltage and resistance are given,

P = \(V^{2}\div R\)

- When the values for voltage and current are given,

P = \(I^{2}\times R\)

### Power Triangle:

In the power triangle, the power (P) will be on the top and current(I) and voltage (V) at the bottom.

- When the values of current and voltage will be given, the formula for finding power will be,

**P = I X V**

- When the values of power and voltage will be given, the formula for finding current will be,

I = \(\frac{P}{V}\)

- When the values of power and current will be given, the formula for finding voltage will be,

V = \(\frac{P}{I}\)

**Ohm’s Law Pie Chart:**

**Ohm’s Law Matrix Table:**

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