Question

A jet plane of wing span $20m$ is travelling towards west at a speed of $400{ms}^{-1}$. If the earth's total magnetic field is $4\times {10}^{-4}T$ and the drip angle is ${30}^o$, at that place, the voltage difference developed across the ends of the wing is

• A. $3.2V$
• B. $6.4V$
• C. $1.6V$
• D. $0.8V$

Answer 1

The correct option is C $1.6V$

The emf induced in a rod travelling in a magnetic field is given by $Bvl$ where $B$ is the magnetic field magnitude, $v$ is the speed of the rod perpendicular to the magnetic field and $l$ is the length of the rod.

The airplane wing can be assumed as a rod. Span of the wing = $20m$

Earth's Magnetic field = $4\times {10}^{-4}T$

Speed of the airplane = $400m/s$

Drip Angle = ${30}^o$

Velocity perpendicular to the magnetic field is $400\text{sin}\left({30}^o\right)=200m/s$

Induced EMF $V=Bvl=4\times {10}^{-4}\times 200\times 20=1.6V$