Electric Field Mapping October 2009

Electric Field Mapping October 2009 - HB 09-25-07 Electric...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: HB 09-25-07 Electric Field Mapping Lab 3 1 Electric Field Mapping Lab 3 Equipment mapping board, U-probe, resistive boards, templates, dc voltmeter (431B), 4 long leads, 16 V dc for wall strip Reading Your textbook. Precautions 1. Before turning mapping board over, remove voltage leads from board. 2. Turn mapping board over by grasping two diagonal corners of board. Please do not grasp edges of mapping board, which may break a wire underneath the board near the edge. 3. Handle resistive boards carefully by edges. It is easy to scratch the resistive coating. 4. During the experiment, keep checking that the knurled nuts, particularly the one to the U-probe, are tight. 1 Description and Theory The force between charged particles is attributed to an electric field ~ E which has the di- mensions of force per unit charge. A charge q in the presence of an electric field produced by other charges experiences a force q ~ E . Another useful quantity is the voltage or potential (these two words are equivalent), which have the dimensions of work per unit charge, or in S.I. units, joules/coulomb (J/C). This last combination of units, J/ C), is called the volt (V). The potential between two points a and b, or the potential at a with respect to b, is given by V a- V b = V ab = R b a ~ E d ~ , where d ~ is a differential displacement. If a surface is constructed so that the electric field ~ E is always perpendicular to it, the potential difference between any two points on the surface will be zero. The surface has a constant voltage and is called an equipotential surface. If several charged conductors exist in a region of vacuum or air, electric field lines and equipotential surfaces can be constructed. A voltmeter is an instrument that has two metal probes. If the two probes are put in contact with any two conductors, the voltmeter will give the voltage or potential between the two conductors. But the voltmeter will not give the voltage between two points in vacuum or air because vacuum or air cannot supply the necessary charge or electrical current necessary to make the voltmeter work. It can be shown that if perfect conductors are embedded in a homogeneous resistive medium, the electric field and equipotentials are the same as in vacuum. This is the technique used in this experiment. Highly conducting paint is used to paint electrodes on a flat resistive board. Voltage differences are applied to the electrodes and the equipotential surfaces in the resistive medium are found by using a voltmeter....
View Full Document

This note was uploaded on 03/25/2011 for the course PHY 102 taught by Professor Khurana during the Spring '11 term at NYU.

Page1 / 6

Electric Field Mapping October 2009 - HB 09-25-07 Electric...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online