Current & Potential Difference | Electricity | Physics | FuseSchool

Summary

This video covers the relationship between current, resistance, and potential difference (voltage), demonstrating how to calculate resistance using Ohm's law (V = IR). It explains the measurement of potential difference across components using a voltmeter in parallel and current with an ammeter in series. The video walks through practical examples, highlighting how to rearrange the equation to solve for current and resistance. By the end, viewers understand the importance of these electrical concepts, how to use voltmeters and ammeters, and how to apply Ohm's law to calculate electrical values.

Takeaways

• 💡 Potential difference, also known as voltage, is essential to make a current flow across an electrical component.
• 🔋 Cells or batteries provide the potential difference required for current flow in a circuit.
• 📏 Ohm's law links potential difference (V), current (I), and resistance (R) using the equation V = IR.
• ⚡ Voltage is measured in volts (V), current is measured in amperes (A) or capital I, and resistance is measured in ohms (Ω) represented by R.
• 🔄 The V = IR equation can be rearranged to find either current, voltage, or resistance depending on the values provided.
• 🔧 A voltmeter is used to measure potential difference and must be connected in parallel with the component being measured.
• 🔌 An ammeter is used to measure current and is connected in series with the component.
• 🧮 To calculate resistance, both current and voltage must be measured, and values substituted into the V = IR equation.
• 📝 A worked example showed that rearranging the formula to I = V/R gave a current of 0.3 amps.
• 📚 The summary emphasized the key concepts of voltage, current, resistance, and how to measure and apply them using Ohm's law.

Q & A

What is the relationship between current, resistance, and potential difference?

Ohm's law states that the potential difference (voltage) is equal to the current multiplied by the resistance, expressed as V = I × R.

What is potential difference also known as, and why is it important?

Potential difference is also known as voltage. It is important because it is required to make a current flow across an electrical component.

How do cells or batteries contribute to a circuit?

Cells or batteries provide the potential difference (voltage) needed to make a current flow in the circuit.

What are the units for potential difference, current, and resistance?

Potential difference (voltage) is measured in volts (V), current is measured in amperes (A), and resistance is measured in ohms (Ω).

How do you rearrange the formula V = I × R to find the current?

To find the current (I), rearrange the formula to I = V ÷ R, which means current is equal to the potential difference divided by the resistance.

How is the potential difference measured across a component in a circuit?

Potential difference is measured using a voltmeter, which must be connected in parallel with the component you are measuring.

How is current measured in a circuit?

Current is measured using an ammeter, which should be connected in series (in line) with the component to measure the current.

What is the correct setup if you want to measure both current and potential difference in a circuit?

To measure both, place the ammeter in series with the component and the voltmeter in parallel with the component.

How can you calculate resistance once you know the current and potential difference?

Once you have measured the current and the potential difference, you can substitute these values into the equation V = I × R to solve for resistance (R = V ÷ I).

What is the resistance of a lamp if the potential difference is 1.5 volts and the current is 1 amp?

The resistance would be 1.5 ohms, calculated using the formula R = V ÷ I.