Class 9 (Science Assignment)

 

 Electricity and Magnetism

Electricity and magnetism are closely related forms of energy. In the early 19th century, scientist Hans Christian Oersted discovered that an electric current flowing through a wire produces a magnetic field around it. This finding helped scientists understand that electricity and magnetism are not separate phenomena, but part of a combined force known as electromagnetism.

One important application of electromagnetism is the electromagnet. An electromagnet is made by wrapping a coil of wire around an iron core and passing an electric current through the wire. When the current flows, the iron core becomes magnetized and acts like a temporary magnet. When the current stops, the magnetism disappears. Electromagnets are widely used in devices such as electric bells, cranes for lifting heavy metal objects, and electric motors.

Electric motors are machines that convert electrical energy into mechanical energy. They work because a current-carrying coil placed inside a magnetic field experiences a force, causing it to rotate. This principle is also used in generators, but in reverse: mechanical energy is used to rotate a coil within a magnetic field, producing electricity.

Understanding the relationship between electricity and magnetism allows engineers to design machines that power industries, homes, and communication systems. Without electromagnetism, we would not have many modern technologies, from fans and refrigerators to speakers and trains.

Questions

1.     What did Oersted discover about electric current and magnetism?

2.     How is an electromagnet created, and why is it called “temporary”?

3.     Give two examples of devices that use electromagnets.

4.     What is the main function of an electric motor, and how does it work?

5.     How does the working principle of a generator differ from that of a motor?

6.     Why is electromagnetism important in modern technology?