Proper units, please ?

[Externet]

Hi.

In the formula E = V B L for the "Conclusions" paragraph at near bottom of page

----> http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract/8630/report/F

 

B being 0.00004 Tesla,

V being 2 metres/second,

L being 300 metres;

 

Should the V,L units be in centimetres or metres for E to be Volts ?

 

[ Did not copy and paste the pertinent portion here because figure 4 shows 'Copyright' ]

 

 

[studiot]

V is in metres per second

L is in metres

E is in volts

B is in Tesla or webers per square metre

 

Then everything is in rationalised MKS units (ISO metric).

 

Note also that your formula uses the vector cross product VxB, since both B and V are vectors.

This would normally also have a cosine of the angle between them, but since this is 90 cos(90) = 1.

Edited October 12, 2014 by studiot

[Externet]

Thanks again, studiot.

 

Solving with metres, the voltage that the strait of Gibraltar tidal current could produce on MHD with the earth magnetic field, is 24 millivolts. A surprisingly low figure.

Solving with centimetres, is 240 Volts.

 

Magnetic field N <---> S; current E <---> W

[studiot]

Millivolts sounds right.

 

Think of a solar panel or Hall effect generator.or even a humble accumulator.

 

They achieve higher voltages by series connection od multiple unts.