KERALA PSC / PHYSICS / MAGNETISM / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE / KERALA PSC PRELIMINARY / NOTES

 

KERALA PSC / PHYSICS / MAGNETISM / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE / KERALA PSC PRELIMINARY / NOTES

KERALA PSC / PHYSICS / MAGNETISM / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE / KERALA PSC PRELIMINARY / NOTES

·      Lode stones are natural magnets, because of the directional property, the substance was called Lodestone or leading stone.

·      Substances, when placed in a strong magnetic field acquire a weak magnetism in a direction opposite to that of applied magnetic field are known as diamagnetic substances. These substances are found to be somewhat repelled when brought closer to the ends of a strong magnet.

·      Diamagnetic materials have negative susceptibility

·      Bismuth, antimony, zinc, silver, copper, gold, lead, water, alcohol, hydrogen and the inert gases are diamagnetic

·      The law of magnetic poles states that like poles repel, unlike poles attract

·      A freely suspended magnet stands vertical at magnetic south pole

·      The substances which are strongly magnetized by relatively weak magnetic field and acquire magnetism in the same sense as the external magnetic field, are known as ferromagnetic substances. These substances are attracted fast towards a magnet when brought close to either of the poles of the magnet. Iron, Nickel, Cobalt, Magnetite etc…, are some examples of ferromagnetic substances. Platinum, solutions of salts of iron, oxygen, manganese, palladium, osmium etc…, are examples of paramagnetic substances.

·      A pair of unlike magnetic poles of equal strengths separated by a small distance constitute a magnetic dipole. The magnetic dipole moment M.

·      Units of dipole moment are Joule/Tesla or ampere Xmetre².

·      Every atom of a diamagnetic substance has not magnetic dipole moment equal to zero.

·      Ferromagnetism is just an alternative name for strong paramagnetism

·      Inside a magnet, direction of magnetic lines of force is from south to north

·      Paramagnetism is temperature dependent

·      Diamagnetism is independent of temperature

·      Soft iron is more strongly magnetized than steel. Soft iron loses the magnetism as soon as current is switched off but steel retains some magnetism.

·      Oxygen is paramagnetic

·      Tesla is the unit of strength of magnetic field.

·      The instruments which are dependent of magnetic power of electricity are fan, telephone receiver, Dynamo etc…

·      Temperature above which a ferromagnetic substance becomes paramagnetic is called curie temperature of the substance. Curie temperature of temperature of iron is 770⁰C

 

KERALA PSC / PHYSICS / MAGNETISM / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE / KERALA PSC PRELIMINARY / NOTES