# Electromagnet Lab - Oersted, Right-Hand Grip Rule, Relay, Bell, Motor

> Middle-school electromagnetism: Oersted's experiment, solenoid poles and field lines, electromagnet strength, relay alarms, electric bell, motor and generator.

- URL: https://qilingtools.com/en/physics/electromagnet
- Category: Physics Tools (https://qilingtools.com/en/physics)
- Tags: [Physics](https://qilingtools.com/en/tags/physics), [Education](https://qilingtools.com/en/tags/education)
- Last updated: 2026-10-29
- Price: Free, no sign-up
- Privacy: Runs locally in the browser; files are never uploaded

An interactive tour of the electricity and magnetism unit of middle-school physics. Close the switch and watch a compass under a wire swing; swap the battery or the winding and the solenoid's field lines, the compasses around it and its N and S poles change, to fix the right-hand grip rule. Other pages count pins picked up by an electromagnet, run relay alarms, animate an electric bell, and show the motor and generator effects.

## How to use

1. Choose a topic at the top, such as Solenoid or Relay
2. Change the current direction, winding, current, turns, temperature or water level
3. Watch the needles, armature, contacts and lamps, and read the status line
4. Try Practice for random multiple-choice questions with instant feedback

## Features

- Oersted's experiment with switchable current direction and wire above or below the needle
- Solenoid field lines computed from summed line currents, with compasses pointing along the real field
- Electromagnet picking up pins vs current, turns and iron core, including a series comparison
- Relay in four settings: motor control, temperature alarm, water level alarm, burglar alarm
- Animated electric bell, force on a conductor, and induced current from a draggable conductor
- Nine kinds of random questions, with diagrams for the solenoid ones

## FAQ

### How do I use the right-hand grip rule?

Grip the coil with your right hand so your curled fingers follow the current round the turns; your thumb points to the N pole. Mark the current direction from the battery's + terminal first, then see whether the current in the front of the coil runs up or down.

### How can I make an electromagnet stronger?

Increase the current, add more turns, or put an iron core inside. Reversing the current only swaps the N and S poles; it does not change the strength. In class the number of pins picked up shows the strength.

### How does a relay let a low voltage control a high voltage?

A relay has two separate circuits. The control circuit only powers the electromagnet, at low voltage and small current. When the electromagnet pulls the armature down, its contacts close the working circuit, which can run a 220 V motor or lamp. People only touch the safe low-voltage side, and control can be automatic or remote.

### What is the difference between the motor and generator effects?

A motor uses the force of a magnetic field on a current to turn electrical energy into kinetic energy, so its circuit has a power supply. A generator uses electromagnetic induction: a conductor in a closed circuit cuts field lines and a current is induced, turning kinetic energy into electrical energy, so its circuit has a meter instead of a supply.

### Why is there no current when the conductor moves up and down?

Here the field lines are vertical. Moving up or down runs along the field lines without cutting them, so no current is induced. Moving left or right cuts them, and reversing the motion reverses the current.

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