04/10/2014 Electromagnetism - Notes Quiz

Explanation
Electric charges, whether positive or negative, are responsible for creating magnetic fields. When charges move, they produce a magnetic field around them. This phenomenon is known as electromagnetism and is a fundamental principle in physics. Therefore, it can be concluded that flowing electric charges create magnetic fields.

Explanation
Electric fields are different from magnetic fields because they exert a force on a charge in the same or opposite direction, depending on the charge's polarity. Electric fields are created by electric charges and can attract or repel other charges. Magnetic fields, on the other hand, exert a force on moving charges and are created by moving electric charges or magnetic materials.

Explanation
Looping a wire into a coil will create a combined magnetic field. When a current flows through a wire, it creates a magnetic field around it. When the wire is looped into a coil, the magnetic fields of each loop combine to form a stronger magnetic field. This combined magnetic field is useful in various applications such as electromagnets, transformers, and inductors.

Explanation
An electromagnet is created when an iron core is placed inside a looped wire or solenoid. When an electric current flows through the wire, it creates a magnetic field around the wire. The iron core enhances the strength of this magnetic field by concentrating the magnetic lines of force. This makes the electromagnet stronger and capable of attracting or repelling objects, depending on the direction of the current. Electromagnets are widely used in various applications such as electric motors, generators, speakers, and magnetic locks.

Explanation
Electromagnets are able to change their strength and direction because they rely on the flow of electric current. By controlling the current passing through the coil of wire, the strength of the magnetic field produced by the electromagnet can be adjusted. Similarly, by changing the direction of the current, the direction of the magnetic field can be altered. Therefore, the correct answer is "current" or "Current".

Explanation
Electric motors use electromagnets to turn an axle. The term "motors" refers to the general category of devices that convert electrical energy into mechanical energy. In this context, "Motors" with a capital "M" could be referring to a specific brand or type of electric motor. Regardless, both "motors" and "Motors" are correct answers as they accurately describe the devices that use electromagnets to turn an axle.

Explanation
Loudspeakers use a solenoid wrapped around one pole of a permanent magnet. Sound is reproduced as the changing current produces a change in magnetic fields.

Explanation
A generator is a device that converts mechanical energy into electrical energy. It does this by utilizing a rotating coil of wire, also known as a solenoid, placed in a magnetic field. When the coil rotates, it cuts through the magnetic field lines, causing an electric charge to be generated. This process allows generators to produce electricity by converting the mechanical energy provided to them into electrical energy.

Explanation
Generators resemble electric motors but generate electricity instead of using it. Electric motors convert electrical energy into mechanical energy to perform work, while generators do the opposite by converting mechanical energy into electrical energy.