Introduction In 1833, German physicist Heinrich Lenz gave a general law for determining the direction of induced emf and hence that of induced current in a circuit. Lenz’s law states that the direction of induced current in a circuit is such that it opposes the cause or the change which produces it. Thus, if the … Read more
History John Ambrose Fleming, an English electrical engineer, is credited with inventing the Fleming right-hand rule in the late 19th century. The thumb, index finger, and middle finger of the left hand are used in the right-hand rule. Statement and Definition Flemings right hand rule gives the direction of induced current set up in a … Read more
There are two types of laws which govern the phenomenon of electromagnetic induction: A. Faraday’s laws which give us the magnitude of induced emf. B. Lenz’s law which gives us the direction of induced emf. A. Faraday’s laws of electromagnetic induction: These can be stated as follows: First Law Whenever the magnetic flux linked with … Read more
Electricity and magnetism are intimately connected. In the early part of the nineteenth century, the experiments of Oersted, Ampere and others established that moving charges (currents) produce a magnetic field. The converse effect is also true i.e., moving magnets can produce electric currents. In 1831, Michael Faraday in England and almost simultaneously Joseph Henry in … Read more
The materials which can be elastically stretched to large values of strain are called elastomers. For example, rubber can be stretched to several times its original length but still it can regain its original length when the applied force is removed. There is no well-defined plastic region, rubber just breaks when pulled beyond a certain … Read more
Modulus of Elasticity The modulus of elasticity or coefficient of elasticity of a body is defined as the ratio of stress to the corresponding strain, within the elastic limit. Modulus of elasticity, E = Stress / Strain Unit and Dimension The SI unit of modulus of elasticity is Nm-2 and its dimensions are [ML-1T-2]. Different … Read more
From experimental investigations, Robert Hooke, an English physicist (1635-1703 A.D.), formulated in 1679 a law known after him as Hooke’s law which states that the extension produced in a wire is directly proportional to the load applied. In 1807, Thomos Young pointed out that the strain is proportional to the extension of the wire and … Read more
If a small load is suspended from a wire, its length increases. When the load is removed, the wire regains its original length. But if a sufficiently large force is suspended from the wire, it is found that the wire does not regain its original length after the load is removed. The maximum stress within … Read more
Definition If a body gets deformed under the action of an external force, then at each section of the body an internal force of reaction is set up which tends to restore the body into its original state. The internal restoring force set up per unit area of cross-section of the deformed body is called … Read more
By a rigid body, we generally mean a hard solid object having a definite shape and size. In reality, solid bodies are not perfectly rigid. They can be stretched, compressed and bent. When an external force is applied, a body may get deformed. When the deforming force is removed, some bodies tend to regain their … Read more
