Physics Topic
Voltage, Resistance, and Ohm's Law
- Read notes
- Flashcards
- Quiz
- Confident
Study focus - 3 things
- Voltage pushes charge around a circuit; resistance opposes current
- Ohm's law is voltage = current x resistance
- Use V = IR carefully, with volts, amperes, and ohms
Section 1Voltage
Voltage, or potential difference, is the push that moves charge around a circuit. It is measured in volts, written V. A higher voltage can push more current through the same resistance.
Section 2Resistance
Resistance is how much a component opposes current. It is measured in ohms, written Ω. A high resistance makes it harder for current to flow.
Section 3Ohm's law
Ohm's law says voltage = current x resistance, or V = IR. Here's the trick: write the formula first, substitute values second, then calculate. This helps avoid swapping current and resistance.
Section 4Circuit meaning
In a phone charger or a small school circuit, voltage, current, and resistance are linked. If resistance increases and voltage stays the same, current decreases. That is why thin or damaged wires can cause problems.
Examples
A current of 2 A flows through a 6 Ω resistor. Find the voltage.
Use V = IR. V = 2 x 6 = 12 V.
A small speaker in a sound system has 8 Ω resistance and 3 A current. What voltage is across it?
Use Ohm's law: V = IR = 3 x 8 = 24 V.
Now let's water it
Session runs notes to flashcards to quiz back-to-back.