MA High School Introductory Physics MCAS Module 6 electricity and magnetism: a complete overview of electric charge and Coulomb's law, current and Ohm's law, electrical energy and power, series and parallel circuits, magnetism, and electromagnetic induction

What Module 6 actually demands

Module 6 covers electricity and magnetism, which the Massachusetts STE framework spreads across two reporting categories rather than one. The force topics, electric charge and Coulomb's law (HS-PS2-4) and magnetism and electromagnetic induction (HS-PS2-5), live in Motion and Forces; the energy of fields (HS-PS3-5) lives in Energy. The reference sheet gives two of this module's formulas, Ohm's law and electrical power, but leaves the circuit rules and all of magnetism for you to recall. The standards lean on using mathematics (the circuit formulas), developing models (circuit diagrams and field lines), and constructing explanations (how induction works), under cause and effect and systems and system models.

This guide ties together the matching dot-point pages, each with its own practice questions: electric charge and Coulomb's law, current and Ohm's law, electrical energy and power, series and parallel circuits, magnetism and magnetic fields, and electromagnetic induction.

Electric charge and Coulomb's law

There are two kinds of charge, positive and negative, and the rule is like repel, unlike attract. Coulomb's law says the electric force is proportional to the product of the charges and inversely proportional to the square of the distance, tested through proportional reasoning (double the distance, quarter the force). It has the same inverse-square form as gravity, but the electric force can push or pull while gravity only pulls. Charge is conserved.

Current and Ohm's law

Current is the flow of charge (amperes), voltage is the push that drives it (volts), and resistance is the opposition (ohms). Ohm's law $V = IR$ links them and is on the reference sheet; rearrange to $I = V/R$ or $R = V/I$. At fixed voltage, current and resistance are inversely related, so more resistance means less current. This is the workhorse formula for circuit calculations.

Electrical energy and power

Electrical power is the rate of transferring energy, $P = IV$ (on the sheet), in watts. The energy a device uses is $E = Pt$ (convert time to seconds for joules). Circuits transform electrical energy into light, heat, motion, or sound, never destroying it, with heat the usual waste. A higher-power device transfers more energy per second and runs up energy use faster.

Series and parallel circuits

In series (one path), the current is the same and the voltage divides; resistance adds, and one break stops everything. In parallel (separate branches), the voltage is the same across each branch and the current divides; adding branches lowers total resistance, and one branch can fail while others work. Homes are wired in parallel so each device gets full voltage and switches independently. Swapping the series and parallel rules is the most common error.

Magnetism and magnetic fields

Magnets have north and south poles, with like poles repelling and unlike attracting, and are surrounded by a magnetic field (lines from north to south, strongest at the poles). The key link the MCAS tests: an electric current produces a magnetic field, the basis of the electromagnet, which switches on and off with the current and grows stronger with more current, more turns, or an iron core.

Electromagnetic induction

The reverse of the electromagnet: a changing magnetic field produces a current in a conductor. Moving a magnet into a coil induces a current; a stationary magnet in a steady field induces none. The induced current grows with a stronger magnet, faster motion, or more turns. A generator turns a coil in a field so the field constantly changes, converting kinetic energy into electrical energy, the reverse of a motor and the source of most electricity.

Check your knowledge

A mix of recall, calculation, and explanation questions covering Module 6. Attempt them under timed conditions, then check against the solutions.

1. State whether two positive charges attract or repel. (1 mark)
2. Two charges feel a force $F$. The distance between them is doubled. State the new force. (2 marks)
3. A current of $3.0$ A flows through a $4.0$ ohm resistor. Calculate the voltage across it. (2 marks)
4. A $12$ V battery drives a $2.0$ A current through a component. Calculate its resistance. (2 marks)
5. A device runs at $120$ V and draws $0.50$ A. Calculate its power. (2 marks)
6. In a series circuit, state how the current through each component compares. (1 mark)
7. In a parallel circuit, state how the voltage across each branch compares to the battery voltage. (1 mark)
8. State what happens when the north pole of one magnet is brought near the north pole of another. (1 mark)
9. State what produces the magnetic field in an electromagnet. (1 mark)
10. State the condition needed to induce a current in a coil, and the energy transformation a generator performs. (2 marks)