A helicopter rises vertically upwards with a speed of 100 `m//s`. If the helicopter has a length of 10m and horizontal component of earth's magnetic field is `5 xx 10^(-3)Wb//m^(2)`, then the induced emf between the tip of the nose and the tail of the helicopter is

Options

A. 50 V
B. 0.5 V
C. 5 V
D. 25 V

Answer

C

Explanation

In case of motional emf, the motion of the conductor in the field exerts a force on the free charge in the conductor, so that one end of the conductor becomes positive, while the other negative resulting in a potential difference across its ends due to which a non-conservative electric field is set up in the conductor. In steady state the magnetic force on the free charge is balanced by the electric force due to induced field.
`qE=qvB` or `q=((v)/(i))qvB`
i.e., `v=BvI`
So, the induced emf between tip of nose and tail of helicopter is given by
`E=BvI`
`=5xx10^(-3)xx10xx100`
E=5V