Electric Field
In physics, fields describe regions of space where every point is assigned a specific physical quantity (or value). Consequently, any object placed within a field may experience specific behaviors or interactions due to its presence.
Many fields exert a physical force on objects placed within them. Take a gravitational field as an example: a mass placed in a gravitational field experiences a force determined by the strength and nature of that field. This force is a vector quantity, meaning it has both a magnitude and a direction—specifically pointing toward the mass generating the field. To illustrate this, fields are commonly represented using vector arrows that indicate the direction and relative strength of the force.
This brings us to electric fields. Electric charges generate fields that exert forces on other charges placed within them.
Interactive
Before we look at the theory, Let's look at an interactive.
- Place a positive charge in the region below. You can alter the strength of the charge be increasing the number of point charges
What do you notice abut the strength and direction of the field? - The arrow represent the force a positive test charge will experience in that field
- Add a sensor. It represents a positive test charge. Move it around
What does the arrow generated represent? - Reset the screen and repeat using a negative charge
What do you notice?
Theory
Lets now look at the theory. The video examines the nature of electric fields and how we represent fields around single charges, multiple charges and plates.
Return to the pHET animation above and see if you recreate the various example mentioned in the video
This fun activity requires you to score hockey goals using your understanding of electric fields.
Place either positive charges or negative charges around the screen to get the black test charge into the goal. Try to do it with the least number of charges.
Level one is easy, but three is a challenge!