Physical Science: Electromagnetism - Class -IX

An electric generator uses electromagnetic induction to convert mechanical energy into electrical energy, which is the inverse function of an electric motor.

A transformer uses electromagnetic induction between two coils to change the voltage of an alternating current, either stepping it up or stepping it down.

Electromagnetic induction is the process where a changing magnetic field induces an electric current in a conductor. The other terms are not standard scientific definitions for this phenomenon.

Michael Faraday is credited with the discovery of electromagnetic induction in 1831, showing that magnetic fields can create electric currents. Oersted discovered the reverse effect, where current creates a magnetic field.

An electric motor uses electrical energy to create rotational movement, which is mechanical energy. This is the inverse of a generator, which converts mechanical energy into electrical energy.

A galvanometer is an instrument used for detecting and measuring small electric currents. The other options are either incorrect terms or unrelated devices.

Maglev (magnetic levitation) trains use powerful electromagnets to lift the train off the track, reducing friction and allowing for high speeds. This is a standard application of electromagnetic repulsion.

A light bulb uses the heating effect of current (incandescence) or gas discharge to produce light, not an electromagnet. Doorbell chimes, hair dryer motors, and MRI machines all rely on electromagnetic principles.

An electromagnet is a solenoid with a ferromagnetic core, which significantly concentrates and strengthens the magnetic field compared to a hollow solenoid. Therefore, an electromagnet is stronger.

A solenoid is simply a coil of wire. When an iron core is inserted, the magnetic field is amplified, turning the assembly into an electromagnet.

The magnetic field strength of a solenoid is directly proportional to the number of turns in the coil. Increasing the number of coils increases the density of the magnetic field lines.

A solenoid is defined as a coil of wire that acts as a magnet when an electric current passes through it. It is the basic structure for creating an electromagnet.

Oersted's experiment showed that a compass needle deflects when placed near a current-carrying wire, and the direction of deflection depends on the direction of the current.

Hans Christian Oersted discovered the link between electricity and magnetism in 1820 when he observed a compass needle moving near a live wire during a lecture.

Electromagnetism is the study of the interaction between electric currents and magnetic fields. This interaction is the basis for motors, generators, and electromagnets.