AP Physics C: Electricity and Magnetism Flashcards: Ampère's Law
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 11 cards to help you master important concepts.
In the equation $\oint\vec{B}\cdot d\vec{l}=\mu_{0}I_{enc}$, what does the term $I_{enc}$ represent?
$I_{enc}$ represents the total net current that is enclosed by, or passes through, the imaginary Amperian loop.
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In the equation $\oint\vec{B}\cdot d\vec{l}=\mu_{0}I_{enc}$, what does the term $I_{enc}$ represent?
$I_{enc}$ represents the total net current that is enclosed by, or passes through, the imaginary Amperian loop.
For a long solenoid, how would you increase the magnetic field inside it without changing the solenoid's physical structure?
According to the equation $B=\mu_{0}nI$, you can increase the magnetic field inside the solenoid by increasing the current (I) flowing through its coils.
What is the equation for the magnetic field near a long, straight current-carrying wire, derived from Ampère's Law?
The magnetic field (B) at a distance (r) from a long, straight wire with current (I) is given by the equation $B=\frac{\mu_{0}I}{2\pi r}$.
State the integral form of Ampère's Law.
The integral form of Ampère's law is $\oint\vec{B}\cdot d\vec{l}=\mu_{0}I_{enc}$, which relates the line integral of the magnetic field around a closed loop to the enclosed current.
What fundamental physical principle does Ampère's law describe?
Ampère's law describes the fundamental principle that a magnetic field is created by a moving charge carrier, or more generally, an electric current.
What is Ampère's Law?
Ampère’s law relates the magnitude of the magnetic field along a closed imaginary path to the current enclosed by that path.
In the solenoid equation $B=\mu_{0}nI$, what does the variable 'n' represent?
The variable 'n' represents the turn density of the solenoid, defined as the number of turns (or loops) per unit length.
What is an Amperian loop?
An Amperian loop is a closed imaginary path used in Ampère's law to calculate the magnetic field generated by an enclosed electric current.
What is the equation for the magnetic field inside a long solenoid, derived from Ampère's Law?
The magnetic field (B) inside a long solenoid is given by the equation $B=\mu_{0}nI$, where 'n' is the number of turns per unit length.
Using the equation for a long, straight wire, what happens to the magnetic field strength if you double the distance (r) from the wire?
According to $B=\frac{\mu_{0}I}{2\pi r}$, the magnetic field is inversely proportional to the distance. Doubling the distance (r) will halve the magnetic field strength.
How is Ampère's Law related to Maxwell's equations?
Ampère’s law, with Maxwell’s addition, forms the fourth equation in Maxwell's equations, the set of fundamental equations that fully describe electromagnetism.