Can You Get Electrocuted On A Flight?

A Boeing 777 is flying due north at v = 900 km/h v=900\text{ km/h} (typical cruising speed) and at an altitude where the vertical component of the Earth's magnetic field is B = 50 μ T B=50~\mu T . The wingspan of the 777 is about 60 m. Determine the induced voltage in Volts across the tips of the wings.


The answer is 0.75.

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

7 solutions

Milly Choochoo
Mar 13, 2014

Oh the classic Brilliant E&M question...

First off, convert the velocity from km/h to m/s

900 k m h = 250 m s 900 \frac{km}{h} = 250 \frac{m}{s}

Now, as the conducting plane flies through this uniform magnetic field, the charges inside will feel a magnetic force which will cause the positive charges to move to the left tip. This new movement of charge (which is otherwise known as current) will also feel a magnetic force that will point backwards. So that means that the plane must be exerting a force so that it can maintain a constant velocity, thereby holding the force felt by the charges due to their initial northward velocity constant. This force is simply the electric force.

F e l e c t r i c = F m a g n e t i c F_{electric} = F_{magnetic}

E q = q v × B Eq = q |v \times B|

E = v B E = vB (the velocity and magnetic field are always perpendicular)

Voltage in an ideal circuit is equal to the constant electric field within the circuit times the distance/length of the wire.

V = E d = v B d V = Ed = vBd

Plug in 250 m s 250 \frac{m}{s} for v v , 50 μ T 50 \mu T for B B , and 60 m 60 m for d d .

V = 0.75 V V = \boxed{0.75 V}

B = 50 * 10^-6 T

v = 900 * 5/18 = 250 m/s

L = 60 m

emf = BLV

emf = 50 * 10^-6 * 250 * 60 = 0.75 volts

no way was confused with the pattern of answering :(

Sumeet Sagar - 7 years, 2 months ago

Log in to reply

I know that feel bro :D

Sherif Elmaghraby - 7 years, 2 months ago

what's b?

Abdullah Khan - 7 years, 3 months ago

Log in to reply

It is the magnetic field and measured in teslas

Sherif Elmaghraby - 7 years, 3 months ago

SAME METHOD I WAS USED...

kuldeep ugale - 7 years, 2 months ago

forgot changing the velocity :(

Salman Dar - 7 years, 2 months ago
Rohan Rao
Mar 6, 2014

Use the concept of Motional EMF. The induced voltage is BvL = 0.75V, when numbers are plugged in with correct SI Units.

damn....used it in mph instead of mps!!!!....

Yash Jaiswal - 7 years, 3 months ago

Log in to reply

next time you copy the same comment from someone else , try to change a little in it :D

Sherif Elmaghraby - 7 years, 3 months ago

Hi guys..can someone please help me with my 4th year high school physics?please..I'm not that smart like u guys..I need help.

Jetro Amian - 7 years ago

The voltage V V generated on moving a conductor by a magnetic field B B is given by Faraday's Law or the rate of change of magnetic flux: V = Δ ( B A ) Δ t V=\frac{\Delta (BA)}{\Delta t} , where A A is the area perpendicular to the magnetic field covered by the conductor in time t t .

For a plane flying with a speed v = 900 k m / h v = 900km/h , wingspan l = 60 m l = 60m , in a constant magnetic field B B , the voltage generated:

V = Δ ( B A ) Δ t V = B Δ A Δ t = B v l = 50 × 1 0 6 × 900 × 1000 60 × 60 × 60 = 0.75 V V=\frac{\Delta (BA)}{\Delta t} \Rightarrow V=\frac{B\Delta A}{\Delta t} = Bvl = 50 \times 10^{-6}\times \cfrac{900\times 1000}{60\times 60}\times 60 = \boxed{0.75}\space V

Jabale Rahmat
Mar 26, 2014

Voltage/Potential difference = Work Done/ Time

Work Done = Force * Distance

Force = BQv

v = 250m/s

B= 50*10E-6

therefore, volt = 50*10E-6 * 250 * 60 = 0.75 V

Senthil Kumar
Mar 12, 2014

E = Blv; B= 50 micro tesla; l=60m; v=900 km/hr=250 m/s; E= 0.75 V

Venture Hi
Mar 6, 2014

EMF or electromagnetic force is the product of L, v and B where L is length in meters, v is the speed in m/s and B is in Tesla.

Oh, answer is NO :-)

Venture HI - 7 years, 3 months ago

damn....used it in mph instead of mps!!!!.....

Sayam Chakravarty - 7 years, 3 months ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...