Electric Potential and Voltage
Voltage is the energy per unit charge.
About this topic
Electric potential is the energy per unit charge at a point, and voltage (potential difference) is the energy transferred per coulomb moving between two points: V = W/q, measured in volts. A 9 V battery gives 9 joules to each coulomb.
Think of voltage as electrical pressure pushing charge round a circuit, or as the height difference in a gravitational analogy. Charge flows from high to low potential, just as a ball rolls downhill. In a uniform field, E = V/d. An electron accelerated through 1000 V gains 1000 electron-volts of kinetic energy, about 1.6 × 10⁻¹⁶ J, which is how old television tubes and electron microscopes get their fast beams.
Voltage is what a voltmeter measures, always connected across a component in parallel. It is why a small battery can power a torch while the thousands of volts in a power line are dangerous.
A common mistake is to say voltage flows through a circuit; voltage is a difference across two points, while current is what flows. A bird on a bare wire is safe because there is no significant potential difference between its feet.
Key ideas
- V = W/q
- Volts = joules per coulomb
- Batteries provide emf
Quick check
Use cases: where Electric Potential and Voltage helps
- Homework: review the key idea behind Electric Potential and Voltage before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Electric Potential and Voltage without notes.
- Visual learning: play with the interactive lab to see how Electric Potential and Voltage changes when you adjust its inputs.
- Teaching a friend: explain Electric Potential and Voltage in your own words, then compare your version with the key ideas.
The same laws describe car crashes, sports, satellites and everyday machines.
Frequently asked questions
What is Electric Potential and Voltage?
Voltage is the energy per unit charge.
What will I learn in Electric Potential and Voltage?
V = W/q. Volts = joules per coulomb. Batteries provide emf.
Is Electric Potential and Voltage part of Physics?
Yes. It is one of 150 Physics topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Electric Potential and Voltage lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Electric Potential and Voltage?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.