Electromagnetism Revision

Flashcards covering key concepts of electromagnetism, electric forces, circuits, motors, generators, induction, and experimental data from lecture notes.

What happens to the magnetic poles when a magnet is cut or broken into smaller pieces?

Each piece becomes a smaller magnet with its own north pole and south pole.

How do magnetic domains differ between unmagnetized and magnetized materials?

Unmagnetized materials have random magnetic domains, while magnetized materials have aligned magnetic domains.

What is electric force, and does it require direct physical contact to act?

Electric force is a noncontact force between charged objects, meaning the objects do not need to touch for the force to act.

What electric charge interaction is illustrated in this diagram?

Opposite charges attract each other, whereas like charges repel each other.

How do distance and amount of charge affect the strength of an electric force?

A greater amount of charge produces a stronger electric force, a smaller distance produces a stronger electric force, and a greater distance produces a weaker electric force.

What components are used to form the electromagnet shown in this diagram?

A current-carrying wire coiled around an iron nail core connected to a battery.

What three modifications can be made to increase the strength of an electromagnet?

Placing an iron core inside the coil, adding more wire turns (loops) around the core, or increasing the electric current.

How can the north and south poles of an electromagnet be reversed?

By reversing the direction of the electric current.

What circuit components are present in this diagram, and when does current flow through it?

The circuit contains a battery, switch, wire, and light bulb; current flows only when the circuit switch is closed.

How does voltage affect electric current and light bulb brightness in a circuit with constant resistance?

Higher voltage produces a larger current and a brighter bulb, while lower voltage produces a smaller current and a dimmer bulb.

Why is a light bulb dimmer when connected to a $6\,V$ battery than when connected to a $12\,V$ battery?

The lower voltage of $6\,V$ provides less push, resulting in a smaller electric current passing through the bulb compared to a $12\,V$ battery.

What are the primary energy transformations in an electric motor and an electric generator?

An electric motor converts electrical energy into mechanical energy, while an electric generator converts mechanical energy into electrical energy.

Why does an electric motor spin continuously?

The permanent magnet and the electromagnet inside the motor alternately attract and repel each other, producing continuous rotation of the coil or shaft.

What process is shown in this diagram, and how is electric current generated?

Electromagnetic induction, where relative motion between a magnet moving into or out of a wire coil induces an electric current.

What three factors can increase the amount of induced current in a wire coil?

Faster relative motion between the magnet and coil, a stronger magnet, or a greater number of coil turns.

What happens to induced current if a magnet remains completely stationary inside a wire coil?

No relative motion occurs, so no continuous electric current is induced.

What are the key differences between Alternating Current (AC) and Direct Current (DC)?

Alternating current (AC) changes direction repeatedly and comes from wall outlets and power stations; direct current (DC) flows in one direction and comes from cells and batteries.

How do permanent magnets and electromagnets compare regarding current requirement, switchability, and pole reversal?

Permanent magnets require no electric current, cannot be switched off, and cannot easily have their poles reversed. Electromagnets require electric current, can be switched off, and can have their poles reversed by reversing current direction.

When an iron nail moves toward the south pole of a magnet, how do the nail's magnetic domains align?

Their north ends point toward the magnet because opposite magnetic poles attract.

Based on this investigation table, which student lifted the most paper clips, and what is the relationship between coil turns and paper clips lifted?

Student 5 lifted the greatest number ($34$ paper clips with $50$ coil turns). As the number of coil turns increases, the number of paper clips lifted increases.

In the electromagnet coil turn investigation using a $9\,V$ battery, what are the independent and dependent variables?

The independent variable is the number of coil turns, and the dependent variable is the number of paper clips lifted.