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Electricity and magnetism study guides cover fundamental force interactions, electric fields, Coulomb’s law, Ohm’s law ($V=IR$), series and parallel circuits, and electromagnetic induction with clear notes, formulas, and practice MCQs.
Before diving into advanced circuit calculations, read our beginner guide on how to learn physics easily to establish a strong study routine.
Electric charge is a fundamental property of matter. Protons carry positive charge (+e) and electrons carry negative charge (−e), where e = 1.6×10&sup-19; C. Like charges repel; unlike charges attract. Coulomb Law gives the magnitude of the force between two point charges: F = kq&sub1;q&sub2;/r², where k = 9×10&sup9; N·m²/C².
Electric current (I): Rate of flow of charge. I = Q/t, measured in Amperes (A).
Voltage (V): Electric potential difference — energy transferred per unit charge. Measured in Volts (V).
Resistance (R): Opposition to current flow. Measured in Ohms (Ω).
Ohm Law: V = IR. Voltage = current × resistance. Valid for ohmic conductors at constant temperature.
Series: Components share the same current. R⊂total; = R&sub1; + R&sub2; + R&sub3;. Voltage divides proportionally to resistance.
Parallel: Components share the same voltage. 1/R⊂total; = 1/R&sub1; + 1/R&sub2; + 1/R&sub3;. Current divides between branches.
Moving charges create magnetic fields. A current-carrying conductor in a magnetic field experiences a force: F = BIL. A changing magnetic flux induces an EMF (Faraday Law): EMF = −NΔΦ/Δt. Lenz Law states the induced current opposes the change causing it.
Essential circuit equations, Ohm’s law formulas, power equations, and SI units for exam revision.
Unit: V (Volts)
Unit: W (Watts)
Unit: N (Newtons)
Unit: N/C or V/m
Unit: A (Amperes)
Unit: V (Volts)
Clear answers to key questions about Ohm’s law, series/parallel circuits, and Faraday’s law.
Ohm’s Law states V = IR: voltage across a conductor is proportional to current through it at constant temperature. Double the voltage and you double the current. Double the resistance and you halve the current.
Series: same current through all components; resistances add; voltage divides. Parallel: same voltage across all branches; total resistance decreases; current divides between branches.
Faraday Law states that a changing magnetic flux through a circuit induces an EMF: EMF = −NΔΦ/Δt. The negative sign (Lenz Law) means the induced current opposes the change that caused it.
To visualize electric fields and practice circuit simulations, explore interactive models at PhET Interactive Simulations.
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Complete physics formula cheat sheet for all circuit and electricity topics.