Ohm's Law relates voltage (E, electromotive force), current (I), and resistance (R) by the equation E = I × R. To calculate current, solve that equation for I, which gives I = E / R — current equals voltage divided by resistance. Units: E in volts, R in ohms, I in amperes. This means current is directly proportional to voltage and inversely proportional to resistance; there is no squaring of E in the basic Ohm's Law relationship.

Memory aids:

• Think of E as an Eagle, I as an Igloo, and R as a Rabbit (Gordon West mnemonic).
• If E is on the left, I and R are on the right (E = I × R).
• If E is on the right, the Eagle is above the others, so I = E / R or R = E / I depending on which is above the other.
• "Eagle over Rabbit" reminds you that I = E / R (Eagle above Rabbit).

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Ohm's Law relates voltage (E, for electromotive force), current (I), and resistance (R). The law states that the voltage across a resistor is the product of the current through it and the resistance: E = I × R. In units this is volts = amperes × ohms, which shows the dimensional consistency.

You can rearrange this relationship to solve for any one variable: I = E / R and R = E / I.

Be careful not to confuse formulas for voltage with formulas for power. For example, I²R appears in power calculations (P = I²R), not as the expression for voltage.

Memory aids / mnemonics:

• Think of E as an Eagle, I as an Igloo, and R as a Rabbit (Gordon West mnemonic).
• If the Eagle (E) is on the left, the Igloo and Rabbit are together on the right — multiplication: E = I × R.
• If E is on the right, the Eagle is always above: R = E / I (E over I) and I = E / R (E over R).

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Ohm's Law relates voltage (E, for electromotive force), current (I), and resistance (R). The law is usually written as E = I × R. Solving that equation for resistance gives R = E / I, so resistance equals voltage divided by current.

Memory aids:

• Gordon West mnemonic: think of E as an Eagle, I as an Igloo, and R as a Rabbit.
• If E (the Eagle) is on the left, I and R (the Igloo and Rabbit) are next to each other on the right, meaning multiplication (E = I × R).
• If E is on top (over another symbol), divide: R = E / I because the Eagle is above the Igloo; I = E / R because the Eagle is above the Rabbit.
• In short: E = I × R, so R = E / I and I = E / R.

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Ohm's Law relates voltage (E), current (I), and resistance (R) by the equation E = I × R. Solving for resistance gives R = E / I.

Substitute the given values: R = 90 volts / 3 amperes = 30 ohms.

Memory aids:

• Think of E as an Eagle, I as an Igloo, and R as a Rabbit: E = I × R (Igloo and Rabbit on the ground). If you need R, use R = E / I (Eagle above Igloo).

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Ohm's Law relates voltage (E), current (I), and resistance (R): E = I × R.

Solving for resistance gives R = E / I = 12 volts / 1.5 amperes = 8 ohms.

See Ohm's Law on Wikipedia: https://en.wikipedia.org/wiki/Ohm's_law

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Ohm's Law relates voltage (E or V), current (I), and resistance (R):

E = I × R

Solving for resistance gives R = E / I. Substituting the given values: R = 12 volts / 4 amperes = 3 ohms. Volts divided by amperes yield ohms, so the circuit resistance is 3 ohms.

See Ohm's Law on Wikipedia

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Ohm's Law relates voltage (E), current (I), and resistance (R):

E = I × R

Solve for current: I = E / R = 120 volts / 80 ohms = 1.5 amperes.

Memory aids:

• E = Electromotive force (Volts)
• I = Intensity (Current, Amperes)
• R = Resistance (Ohms)
• See Ohm's Law on Wikipedia: https://en.wikipedia.org/wiki/Ohm's_law

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Ohm's Law relates voltage, current, and resistance:

E = I × R

Where:

• E is voltage in volts (V)
• I is current in amperes (A)
• R is resistance in ohms (Ω)

We are given voltage and resistance and need current, so rearrange the formula:

I = E / R

Substitute the values:

I = 200 V / 100 Ω = 2 A

Memory aids:

• Ohm's Law: E = I × R
• To find current: I = E / R
• To find voltage: E = I × R
• To find resistance: R = E / I
• (Reference) See Ohm's law on Wikipedia for more detail

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Ohm's Law relates voltage (E), current (I), and resistance (R):

E = I × R

Solving for current gives:

I = E / R = 240 V / 24 Ω = 10 amperes

See Ohm's Law on Wikipedia: https://en.wikipedia.org/wiki/Ohm's_law

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This is an application of Ohm's law. Voltage across a resistor equals current multiplied by resistance: V = I × R. So V = 0.5 A × 2 Ω = 1 V, therefore the voltage is 1 volt.

Memory aids:

• E = I × R (alternate symbol for voltage)
• V = I × R
• See Ohm's Law: https://en.wikipedia.org/wiki/Ohm's_law

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Ohm's Law gives the relationship between voltage (E or V), current (I), and resistance (R):

E = I × R

You can rearrange this to find any one quantity if you know the other two:

• E = I × R
• R = E / I
• I = E / R

For this problem:

• I = 1 A
• R = 10 Ω

E = I × R = 1 A × 10 Ω = 10 V

Therefore, the voltage across the resistor is 10 volts.

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Use Ohm's Law: V = I × R. With a current of 2 amperes through a 10-ohm resistor, V = 2 A × 10 Ω = 20 volts.

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Explanation

In a series circuit there is only one path for current to flow, so the same current passes through every component in that path. Current is the rate of charge flow; because the charges that pass through one component must also pass through the next (there's no alternate route), the current is identical in each element. Voltage, however, can differ across each component and will add up to the total source voltage.

In the animation below, the amount of voltage is indicated by the darkness of the green, and the current is represented by the "walking ant" animation.

Memory aids:

• Series: the letter "S" can remind you that current is the "S"ame through all components.
• Parallel is like train tracks — paths run side by side.
• Series is like a movie series — one episode after another.

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In a parallel circuit each component is connected across the same two nodes, so the potential difference (voltage) across every component is identical even though the currents through them may differ.

In the animation below, the amount of voltage is indicated by the darkness of the green, and the current is represented by the "walking ant" animation.

There is full source voltage on one side and no voltage on the other, and because each component is connected across those same two points, the voltage is the same across all components in a parallel circuit.

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