Question

PART 1: THE ELECTRIC FIELD
Procedure: Assemble in groups of 2-3 around the pod computers. You may also use a laptop or tablet. Open the Charges and Field simulation:
http://phet.colorado.edu/en/simulation/charges-and-fields
and click on the “play” symbol to open. Once the simulation opens, check the box next to grid. Your instructor will show you a few things about this simulation before you begin.
Explore: Answer all questions and all parts below.
1. First, explore by placing a 1 nC positive charge and E-Field Sensor in the test area. Observe the sensor’s arrow as you drag it around the in the field. How does the arrow change as you move it around?
2. Replace the positive charge with a negative charge. To remove charges, drag them back into their box. How does what the E-Field Sensor show differ with the negative charge? How is it the same?
3. How is it different?
4. The E-Field Sensor represents a positive test charge and the arrow represents the force exerted by the E-field on the test charge. Basically, you’re measuring how an electric field, set up by whatever charges are present, would affect a small, positive charge placed there (more on this in class if you haven’t seen this already!).
o Determine the E vs. r relationship for the following charge configurations. This means making a hypothesis, taking data from the simulation, making a graph on Excel (or similar), finding the best-fit relationship.

o (Click on show numbers and tape measure to measure the distances from a field-creating charge to a test charge. The tape measure can be dragged to a specific distance and placed anywhere on the field.)

o Scenario 1: a single positive charge: what is the relationship between E (in V/m) and the distance from the charge (in m)? ▪ Your prediction (fill in the blanks): • If: _______________________________________________

• Then: ____________________________________________

• Because: __________________________________________

▪ Your data:

Scenario 1: A single positive charge (+1.0 nC)
r (m)	E (V/m or N/C)

Answer 1

We knwo that the electricfield lines are originates from positive charge and ends at negative charge

that the field lines from the positive charge are radially outward and at -ve charge are radially inward

when we place 1 nC positive charge and moving the electric field sensor around it

and the electric field of a charge q at a distance r is  

E = kq/r^2

that is as we move the sensor away from the charge the arrow length decreases and we kept the sensor near the charge the arrow lenght increases  

same thing will be for negative charge also but the direction of the arrow is inward that is toward the charge