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# Electric Field Equation and Point Charges

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Activity Three: Place a positive charge and a negative charge close to each other to create a dipole. Again, predict what the field will look like. Then, test your prediction.

If your observation is different than your prediction, explain here what was wrong in your original thinking.

Include in your lab book the equation of the E-field at the black point for the above dipole where d >> s.

Activity Four: Make a line of positive charge. Predict what the field will look like. Then, test your prediction.

If your observation is different than your prediction, explain here what was wrong in your original thinking.

Write in your lab book how to find the electric field of a uniformly charged rod of length L at a distance r away from the center of the rod.

Activity Five: Draw a Parallel-Plate capacitor on the slightly-resistive paper using the conductive ink. Predict what the E-Field is going to look like, then test your prediction using the "E-Field Meter". After that, test your prediction on the website.

Activity Six: Describe, in words and picture again, just what an E-field is. Are there any changes from your original definition?

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Activity One: Describe in your lab book using both, words and/or pictures, the concept of the Electric Field.
Answer: Electric Field is the region in space around an electric charge or a system of charges, within which, other charged particles experience an electrostatic force.
Theoretically, the electric field due to a charged particle or a system of charges, extends upto infinity, but practically this electric field does not show detectable influence on other charged particles beyond a certain limit as the field strength decreases with increase in distance.
The electric field strength or electric field intensity E, for a charged particle or a system of charges, is defined as the ratio of the electrostatic force F, experienced by a positively charged particle + q0 (test charge) placed within the region of the electric field, to the magnitude of charge q0.
Therefore, E = F/ q0 (E and F are vector quantities)
The charges which produce electric field are known as source charges. The point at which Electric Field is to be determined is known as the observation point.

Activity Two: Place a single positive charge upon the screen. Sketch in your lab book what you think the "Electric Field" will look like. After your prediction, turn the "Field" on to see what the E-Field looks like.

Prediction : In the case of a positive charge, the electric lines of force are directed away from the charged particle in all possible directions. The Electric Field lines never cross each other.

Prediction matched with observation.
Write the E-field equation for a positive point-charge here:
Answer: E(r) = (1/ 4πε0) x q/r2
Activity Three: Place a positive charge and a negative charge close to each other to create a dipole. Again, predict what the field will look like. Then, test your prediction.

Prediction:

+q

Fig: Electric Field in a Dipole.
The direction of the Electric field is from the unit positive charge towards the unit negative charge in the dipole.
Prediction matched with the observation.

The electric field at the black spot is given as E = (1/ 4πε) x q/[d2+ (s/2)2]
Since, it is given that d>>s, so on ignoring (s/2)as compared to d, the above equation can be written as E = (1/ 4πε) x q/[d2]
Activity Four: Make a line of positive charge. Predict what the field will look like. Then, test your prediction.

Prediction:

Fig: The electric field (in 2-D) from a line of positive charge.
My prediction matched with the observation.

Write in your lab book how to find the electric field of a uniformly charged rod of length L at a distance r away from the centre of the rod.
Answer: The electric field of a uniformly charged rod of length L at a distance r away from the centre of the rod can be calculated either by taking the help of calculus or by applying Gauss's Law.

Activity Five: Draw a Parallel-Plate capacitor on the slightly-resistive paper using the conductive ink. Predict what the E-Field is going to look like, then test your prediction using the "E-Field Meter". After that, test your prediction on the website.
+ve plate --ve plate

Fig: Lines of force (Electric field) in a parallel plate capacitor.
Activity 6: Activity Six: Describe, in words and picture again, just what an E-field is. Are there any changes from your original definition?

Answer: Electric field Intensity and direction are expressed with the help of Field Lines. The number of field lines gives the intensity of the Electric Field. The arrows on the Field lines gives the direction of the Electric Field. The electric field direction is always from positive charges to negative charges. Hence, electric field lines always originate from positive charge and ends in negative charge.

This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

© BrainMass Inc. brainmass.com October 6, 2022, 10:22 am ad1c9bdddf>
https://brainmass.com/physics/electric/electric-field-equation-point-charges-261731