Test: The Bar Magnet, Magnetism and Gauss’s Law (January 14) - NEET MCQ

Diamagnetic materials are those which when placed in a magnetizing field are feebly magnetized in a direction opposite to that of the magnetizing field. Therefore, it is feebly repelled by a magnet. Example: zinc, gold, etc.

The relative permeability of ferromagnetic materials is much larger than 1. Ferromagnetic substances are those, which when placed in a magnetic field are strongly magnetized in the direction of the magnetizing field, i.e., it is strongly attracted by a magnet.

Diamagnetic materials have a small and negative value of magnetic susceptibility. Paramagnetic materials have a small and positive value of magnetic susceptibility and ferromagnetic materials have a large and positive value of magnetic susceptibility.

Iron is a ferromagnetic material. Ferromagnetism decreases with a rise in temperature, and above a certain temperature called “Curie’s temperature,” ferromagnets become paramagnets. For iron, it is approximately, 800 °C.

Soft iron has high permeability and low retentivity and is used as an electromagnet. The area under the hysteresis loop for soft iron is less. So where the repeated cycles of magnetization occur, there on using soft iron core, energy losses are less. That is why soft iron is used in cores of transformers, galvanometers, generators, etc.

Three quantities are needed to specify the magnetic field of the earth on its surface, namely, the horizontal component, the magnetic declination and the magnetic dip. These are known as elements of the earth’s magnetic field or magnetic elements.

Magnetic dip or inclination at a place is defined as the angle made by the Earth’s magnetic field with the horizontal in the magnetic meridian. It is denoted by δ.
Magnetic declination at a place is defined as the angle between the geographic meridian and magnetic meridian.

No, this statement is false. The Earth always has a vertical component except at the equator. Similarly, the earth always has a horizontal component except at the poles.

Angle of dip is 90^o at geographical North Pole because attraction on the North Pole of needle is very strong and the needle remains in vertical plane. At the magnetic equator, the needle will point horizontally, i.e. dip angle is 0^o. As you move from the magnetic equator towards the magnetic pole, the angle increases in the northern hemisphere. So, the angle of dip is maximum.

If a magnet is freely suspended or inclined or dipped, the angle between the horizontal and the angle of inclination of the magnet that is inclined only by the earth’s magnetic field will indicate the magnetic latitude. The relation is as follows:
tanδ=2tanλ