A horizontal straight wire 10 m long extending from east to west is falling with a speed of 5.0 m s-1, at right angles to the horizontal component of the earth’s magnetic field, 0.30 \(\times\)10-4 Wb m-2 .
- What is the instantaneous value of the emf induced in the wire?
- What is the direction of the emf?
- Which end of the wire is at the higher electrical potential?
A horizontal straight wire 10 m long extending from east to west is falling with a speed of 5.0 m s-1, at right angles to the horizontal component of the earth’s magnetic field, 0.30 \(\times\)10-4 Wb m-2 .
- What is the instantaneous value of the emf induced in the wire?
- What is the direction of the emf?
- Which end of the wire is at the higher electrical potential?
Solution and Explanation
Length of the wire, I = 10 m
Falling speed of the wire, v = 5.0 m/s
Magnetic field strength, B = 0.3 x 10-4 Wb m-2
a. Emf induced in the wire, e = Blv
=0.3×10-4×5×10
=1.5×10-3 V
b. Using Fleming's right had rule, it can be inferred that the direction of the induced emf is from West to East.
c. The eastern end of the wire is at a higher potential.
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Concepts Used:
Faradays Laws of Induction
There are two laws, given by Faraday which explain the phenomena of electromagnetic induction:
Faraday's First Law:
Whenever a conductor is placed in a varying magnetic field, an emf is induced. If the conductor circuit is closed, a current is induced, known as the induced current.
Faraday's Second Law:
The Emf induced inside a coil is equal to the rate of change of associated magnetic flux.
This law can be mathematically written as:
∈\(-N {\triangle \phi \over \triangle t}\)
