Chapter 7: Electric Potential Flashcards
What is electrical potential energy?
The potential energy due to a collection of point charges, also equal to the amount of energy required to assemble the collection of point charges (bring them in from infinity to their current positions).
What are the units of electrical potential energy?
Joules ( J )
Is electrical potential energy a vector or a scalar?
Like all forms of energy, electrical potential energy is a scalar. You can directly add the values instead of breaking them into components like vectors.
Can electrical potential energy be negative?
Yes, it can be positive or negative depending on the values of the charges.
What does the variable r mean in the electrical potential energy equation?
r is the straight-line distance between the two charges Q1 and Q2.
How do you calculate the electrical potential energy due to more than two charges?
Calculate the electric potential energy between each set of charges and add them up.
For example, if you have three charges Q1, Q2, and Q3, you’d find the following:
U(total) = k Q1 Q2 / r(12) + k Q1 Q3 / r(13) + k Q2 Q3 / r(23)
What is another name for the electric potential?
Voltage
What is the electric potential (voltage)?
The electric potential, or voltage, is the amount of energy required to move a charge in an electric field E. Another way to state this is that the electric potential is the energy per unit charge.
How is the electric potential (voltage) related to the electric potential energy?
The electric potential (voltage) is the electric potential energy per unit charge, so V = U/q.
Does electric potential (voltage), V, exist everywhere, or only where two charges are interacting?
Electric potential (voltage), V, can be measured everywhere in space. It is a field.
Does electric potential energy, U, exist everywhere, or only where two charges are interacting?
Electric potential energy (U) is the energy required to bring two or more charges together, so it requires two charges. It does not exist everywhere in space.
When does a voltage difference (delta V) exist between two points in space?
When a charged particle Q can gain or lose energy by moving between the two points in space.
What are the units of electric potential?
Volts ( V )
Is electric potential energy (U) conserved?
Like all other forms of energy, electric potential energy (U) is conserved and can be added to the conservation of energy equations.
A charged particle is moving in a constant electric field E. Can you use kinematics to determine the motion of the charged particle? Why or why not?
In order to use kinematics to solve for the motion of an object, the acceleration must be constant during the motion.
The force on the particle is equal to F = qE, and Newton’s Second Law says F = ma. Thus, if the electric field is constant, the acceleration is constant, and we can use kinematics.
