Science Olympiad Test: Magnetic Effects of Electric Current- 1 - Class 10 MCQ

• A naturally magnetized piece of mineral magnetite is called a lodestone. They are called natural magnets, and they can attract iron. The magnetism property was first discovered in antiquity via lodestones. in which the Middle English refers to the "course stone" or "leading stone"
• Artificial magnets are stronger than naturally occurring magnets like lodestone.
• Again artificial magnets are classified into two types, permanent magnets, and electromagnets.
• Permanent magnets are made of carbon steel or different metal alloys like AlNiCo which is an alloy of Aluminium, Nickel, and Cobalt; or even a nonmetal like a ferrite which can be very strongly magnetized.
• Electromagnets have low carbon steel or special alloys of steel it have a coil of current-carrying material wrapped around them.

Magnetic force acts perpendicular to the motion of the charged particle and as such the speed of the particle remains unchanged.

As per the Right-Hand thumb rule, the direction of curling of fingers of the right hand gives the direction of magnetic field lines.

The most suitable material to be used as the core of an electromagnet is soft iron and it has high permeability but its availability and cost makes it uneconomical.

The four main factors that affect the strength of an electromagnet are the loop count, the current, the wire size, and the presence of an iron core.

Magnetic field due to current-carrying wire is independent of its diameter or cross-sectional area of so long as the current remains the same.

Permanent magnets are made from special alloys (ferromagnetic materials) such as iron, nickel and cobalt, several alloys of rare-earth metals and minerals such as lodestone.

Electric fuses are always connected in series with the live wire. Electric fuses are always connected in series with the live wire.

emf induced is proportional to the rate of change of magnetic flux.
When a magnet is moved towards the coil quickly, the rate of change of flux is larger than if the magnetic is moved slowly, thus larger emf is induced due to the quick movement of the coil.

Generally, a small dynamo requires a permanent magnet. Using Faraday's law of induction, rotating a coil of wire and magnetic fields to convert mechanical rotation into a direct electric current. Thus, a dynamo converts mechanical energy to electrical energy.