6. Which of the following
property of objects can be used
to group nickel and iron objects
together?
O (a) Magnetic attraction
O(b) Heat conduction
O (c)Floatation
O (d) Electrical conduction
Answers
Answer:
Magnetic attraction.
...
....
Answer:
The ancient Greeks and Chinese discovered that certain rare stones, called lodestones, were naturally magnetized. These stones could attract small pieces of iron in a seemingly magical way, and were found to always point in the same direction when allowed to swing freely, suspended by a piece of string, or floating on water. Early navigators used these magnets as rudimentary compasses to help them determine their direction while at sea.
The word "magnet" comes from Magnesia, a district in Thessaly, Greece where it is believed that the first lodestone was mined.
Over the years, magnets have evolved into the high-strength materials we have today. It was discovered that by creating alloys of various materials, one could create similar effects to those found in natural lodestone rocks, and increase the level of magnetism.
However, it was not until the 18th century that the first man-made magnets were created. Progress in creating stronger magnetic alloys was very slow until the 1920s when alnico magnet materials (an alloy of nickel, aluminum and cobalt) were formulated. Ferrite magnets were developed in the 1950s and rare-earth magnets in the 1970s. Since then, the science of magnetism has grown exponentially, and extremely powerful magnetic materials have made miniature and powerful devices possible. (top)