LR Circuits - Review for AP Physics C: Electricity and Magnetism

The video tutorial reviews LR circuits in AP Physics C, focusing on the behavior of circuits with inductors and resistors. It explains the initial and steady-state conditions of current, applies Kirchoff's Loop Rule, and derives equations for current as a function of time. The concept of time constant is introduced, and the tutorial draws an analogy between LR circuits and motion with drag force. The session concludes with a preview of LC circuits.

What components are present in an LR circuit?

• Battery, resistor, capacitor, and switch

• Battery, resistor, inductor, and switch

• Battery, inductor, capacitor, and switch

• Battery, resistor, diode, and switch

What is the initial current in an LR circuit when the switch is closed?

• Maximum current

• Half of the maximum current

• Double the maximum current

• Zero

According to Kirchoff's Loop rule, what is the sum of the electric potential differences around a loop?

• Equal to the inductance

• Equal to the resistance

• Equal to zero

• Equal to the EMF

What is the final steady state current in an LR circuit after a long time?

• EMF divided by resistance

• EMF divided by inductance

• Zero

• Inductance divided by resistance

What mathematical technique is used to derive the equations for current in an LR circuit?

• Fourier transform

• Matrix multiplication

• U substitution and integration

• Differentiation

What is the time constant for an LR circuit?

• Inductance divided by resistance

• EMF divided by inductance

• Resistance divided by inductance

• EMF divided by resistance

What percentage change does one time constant represent in an LR circuit?

• 63.2%

• 50%

• 90%

• 75%

In the analogy between LR circuits and motion, what is the electrical equivalent of acceleration?

• Inductance

• Derivative of current with respect to time

• Voltage

• Current

What is analogous to the force of gravity in the LR circuit analogy?

• Current

• EMF

• Resistance

• Inductance

What role does the inductor play in an LR circuit over a long period?

• It acts as a capacitor

• It opposes changes in current initially but acts like a short circuit over time

• It increases the current

• It decreases the current