Question

A) A horizontal straight wire 10 m long extending from east to west is falling with a speed or $5.0m/s$, 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?

B) A horizontal straight wire 10 m long extending from east to west is falling with a speed of $5.0m/s$, at right angles to the horizontal component of the earth’s magnetic field, $0.30\times {10}^{-4}W/b{m}^2$. What is the direction of the emf?

C) A horizontal straight wire 10 m long extending from east to west is falling with a speed of $5.0m/s$, at right angles to the horizontal component of the earth’s magnetic field, $0.30\times {10}^{-4}Wb/m^2$. Which end of the wire is at the higher electrical potential?

Answer 1

A) Given,
Length of the wire, $l=10m$
Falling speed of the wire, $v=5m/s$
Magnetic field strength, $B=0.3\times {10}^{-4}Wb/m^2$
Emf induced in the wire, $ϵ=Blv$
Putting the values, we get, $ϵ=0.3\times {10}^{-4}\times 10\times ϵ=1.5\times {10}^{-3}V$
Final answer: $ϵ=1.5\times {10}^{-3}V$


B) According to the Fleming’s right-hand rule, if we hold our right-hand forefinger, middle finger and the thumb at right angle to each other, then, if the forefinger represents the direction of the magnetic field in which the conductor is placed and the thumb represents the direction of motion of the conductor or the direction of applied force, then the direction of the middle finger represents the direction of induced current in the conductor.
The current is flowing in the direction from West to East.
Final answer: West to East

C) As the current flows from higher potential to lower potential, then the western end will be at higher potential.
Final answer: Western End