Electromagnetism and its Applications

In the mid-1800s, Hans Oersted discovered that electric current creates a magnetic field, influencing a compass needle. He found that twisting a wire into a solenoid enhances the magnetic force, which can be further amplified by inserting an iron core, forming an electromagnet. Electromagnets are strong but temporary, losing magnetism when the current stops. A practical example is a scrapyard electromagnet, which lifts metal when powered and releases it when off.

What did Hans Oersted discover about the relationship between electricity and magnetism?

• Electricity can be stored in magnets.

• Electricity and magnetism are unrelated.

• Magnets can generate electricity.

• Electric current produces a magnetic field.

How does the direction of electric current affect a compass needle near a wire?

• The needle moves in the direction of the current.

• The needle does not move at all.

• The needle moves in the same direction regardless of current.

• The needle moves in the opposite direction of the current.

What happens to the magnetic force when a wire is twisted into a solenoid?

• The magnetic force disappears.

• The magnetic force decreases.

• The magnetic force remains the same.

• The magnetic force becomes greater.

How can the strength of a solenoid's magnetic field be increased?

• By placing an iron object inside the coils.

• By using a longer wire.

• By using a thicker wire.

• By reducing the number of coils.

What happens to an electromagnet when the electric current is turned off?

• It becomes a permanent magnet.

• It retains its magnetic properties.

• It loses its magnetic properties.

• It becomes stronger.