# Plane immersed in the earth's vertically downward-pointing magnetic field

## Homework Statement

This question and the next two refer to this situation:

http://i.imgur.com/dgJMR.png

A passenger jet is flying over Alaska in level flight at a constant altitude h = 10 km and constant speed of v = 300 m/s, immersed in the earth's vertically downward-pointing magnetic field of B = 30 μT. The distance between the tips of the aircraft's metal wings is d = 50 m.

Part A:
Calculate the potential difference ε between the aircraft's wing tips due its motion through the earth's magnetic field.
(a) ε = 0.0 volts
(b) ε = 0.45 volts
(c) ε = 0.90 volts

Part B
Which wingtip has positive charge, as viewed by a passenger in the airplane who is facing in the direction that the airplane is traveling?
(a) the right wingtip
(b) the left wingtip
(c) neither wingtip

## Homework Equations

emf = d flux / dt

flux = int[B*dA]

## The Attempt at a Solution

For part A, I tried formula above, I get answer C, because I thought I need to calculate difference for both wings? Part B I used F=BIL, however, I get the force is on right wing? What is the relationship between force ans its direction of the plane that traveling?

Thx

Delphi51
Homework Helper
For part A, I used the generator formula V = L*v*B = 50*300*30x10^-6 = 0.45 Volts. Had I used only one wing length I would have gotten half that voltage.

Part B is not a formula question. Use hand rules to figure out which way the electrons are pushed. Then you can tell which side is negative and which is positive.

For part A, I used the generator formula V = L*v*B = 50*300*30x10^-6 = 0.45 Volts. Had I used only one wing length I would have gotten half that voltage.

Part B is not a formula question. Use hand rules to figure out which way the electrons are pushed. Then you can tell which side is negative and which is positive.

Everything makes sense now, thanks!