MAE 488 Quiz 4 EXAM Questions AND Correct Answers
Back EMF is proportional to the motor ___________ - ✔✔speed/ angular velocity
DC motors are based on two concepts from physics: ___________ force and ___________ law. (choose
from: Faraday, magnetic, electric, lorentz, kirchoff) - ✔✔Lorentz, Faraday
Define Lorentz Force - ✔✔is the force generated on a current carrying conductor in the presence of a
magnetic field
Describe the difference between an armature-controlled and a field-controlled DC motor in one or two
sentences. - ✔✔Armature-controlled DC motors vary torque/speed by changing the armature voltage,
keeping the field constant.
Field-controlled DC motors vary torque/speed by changing the field voltage, with constant armature
current.
For a capacitor, i(t)=_____ - ✔✔i(t) = C dv/dt
In an RLC circuit, what would the state variables be, and why? - ✔✔• v_C(t): Capacitor → stores energy
in electric field → state variable is voltage across it
• i_L(t): Inductor → stores energy in magnetic field → state variable is current through it
• State variables must represent stored energy.
Kirchoff's Current law states that the sum of the currents entering the node is equal to : - ✔✔the
currents exiting the node.
Kirchoff's Voltage Law states that the signed sum of the voltages in a closed circuit or loop is equal to: -
✔✔0
Ohm's Law for a resistor in the Laplace domain is: V(s)=_____ - ✔✔V(s) = RI(s)
Back EMF is proportional to the motor ___________ - ✔✔speed/ angular velocity
DC motors are based on two concepts from physics: ___________ force and ___________ law. (choose
from: Faraday, magnetic, electric, lorentz, kirchoff) - ✔✔Lorentz, Faraday
Define Lorentz Force - ✔✔is the force generated on a current carrying conductor in the presence of a
magnetic field
Describe the difference between an armature-controlled and a field-controlled DC motor in one or two
sentences. - ✔✔Armature-controlled DC motors vary torque/speed by changing the armature voltage,
keeping the field constant.
Field-controlled DC motors vary torque/speed by changing the field voltage, with constant armature
current.
For a capacitor, i(t)=_____ - ✔✔i(t) = C dv/dt
In an RLC circuit, what would the state variables be, and why? - ✔✔• v_C(t): Capacitor → stores energy
in electric field → state variable is voltage across it
• i_L(t): Inductor → stores energy in magnetic field → state variable is current through it
• State variables must represent stored energy.
Kirchoff's Current law states that the sum of the currents entering the node is equal to : - ✔✔the
currents exiting the node.
Kirchoff's Voltage Law states that the signed sum of the voltages in a closed circuit or loop is equal to: -
✔✔0
Ohm's Law for a resistor in the Laplace domain is: V(s)=_____ - ✔✔V(s) = RI(s)
