How can I measure electric field strength for my coursework extension?

[jaderberg]

I need to do an extension to a piece of coursework so i thought that a good one (which relates to my initial experiment which was millikans oil drop) would be to try and prove simply that E = V/d. I have about an hour to do it in...does anyone have any ideas how i can go about this?

I can get hold of a very large voltage supply and two metal plates but i don't know how to measure electric field strength...any ideas?

 

[Math Jeans]

You could measure the voltage of the magnet, and the distance between the plates as your baseline for the formula. Then you could put a charged object inbetween the plates and with a spring meter, measure the force, and show that only an electric field with a magnitude of V/d would cause the force that was put upon the charge.

 

[jaderberg]

yeah this is kind of train of thought i was thinking of but some questions:
why would i need to measure the voltage of a magnet?
also what object could i use and how could i charge it with a known amount of charge?

 

[robphy]

Millikan experiment?
http://dev.physicslab.org/Document.aspx?doctype=3&filename=AtomicNuclear_MillikanOilDrop.xml
...given knowledge of the mass and charge of an electron, you can determine the electric field.

Alternatively, does PASCO make an electric field sensor?

 

[Math Jeans]

yeah this is kind of train of thought i was thinking of but some questions:
why would i need to measure the voltage of a magnet?
also what object could i use and how could i charge it with a known amount of charge?

Well, the reason you would need to measure the voltage would be to help prove the formula, as in, you need the initial electric field, and you would use that to show that it would be that electric field that creats the certain force.

Charging is simple if you have the correct materials. If you can simply get an object that can hold a charge, hook it up to a power source and use a multimeter to measure the charge on the object (I hope you have a multimeter).

 

[jaderberg]

robphy this is just an extension thing on top of my millikan experiment (which i already have results for).

maths jeans: oh right, i just didnt really understand where the magnet came into it. say if i used a small sheet of plastic and charged it, wouldn't connecting a multimeter remove the charge?