ECE 331 - TEST 2 QUESTIONS WITH VERIFIED SOLUTIONS LATEST UPDATE 2026
can the voltage across an inductor be discontinuous? - Answers yes, v = L*di/dt, if i(t) has a corner
then the voltage will be discontinuous at that point
can the current through an inductor be discontinuous? - Answers no, v = L*di/dt, if i(t) is
discontinuous the voltage will be infinite, which is physically impossible.
can the voltage across a capacitor be discontinuous? - Answers no, I(t) = c*dv/dt, if v(t) is
discontinuous the current will be infinite, which is physically impossible
can the current through a capacitor be discontinuous? - Answers yes, I(t) = c*dv/dt, if v(t) has a
corner then the current will be discontinuous at that point.
dialectric - Answers what separates a pair of conducting plates (capacitor)
e.g. air, mylar, tantalum, ceramic, titania
maxwells law - Answers q(t) = c*v(t)
conduction current - Answers the type of current that flows in wires
displacement current - Answers the type of current that flows between the plates of a capacitor
energy stored/absorbed/delivered in a capacitor - Answers w(t) = c* 1/2 * v^2
energy delivered: w(t1) - w(t2)
energy absorbed: w(t2) - w(t1)
energy stored is always non negative
energy stored: w(t2) = energy stored at t = t2
Rth = - Answers Voc/isc
RC switch circuit t<0 and t-> inf - Answers DC circuit in S.S. therefore C is an open circuit
open circuit - Answers current is zero
voltage divsion - Answers source * (resistor(s) in parallel w source / resistor + other resistors in series)
Tau for RC switch circuits - Answers tau = Rth*C
RL switch circuit t<0 and t-> inf - Answers DC circuit in S.S. therefore L is a short circuit
current division - Answers source * (1/resistor(s) w current aka in series w L) / (1/resistor(s) + 1/other
resistors in parallel)
Tau for RL Switch Circuits - Answers L / Rth
short circuit - Answers v = 0
v(t) given as equation, Ix(t) = ? - Answers ix(t) = C * dv/dt + V/R (if there's a resistor)
capacitors: I(t) and w(t) - Answers I = C * dv/dt
w = C * 1/2 * v^2
inductor - Answers v = L * di/dt
w = L * 1/2 * I^2
trig identity for sin to cos - Answers sin(a) = cos(a - 90)
RL switch circuits iL(t)= - Answers = iL(inf) + [iL(0) - iL(inf)]*e^(-t/tau)
RC switch circuits vC(t)= - Answers = vc(inf) + [vc(0) - vc(inf)]*e^(-t/tau)
RL ix pos/neg - Answers current:
same dir -
opposite dir +
voltage:
current in dir of source pos to neg +
current in dir of source neg to pos -
RC vx pos/neg - Answers voltage:
matching signs +
switched signs -
current:
source current in dir of vx neg to pos +
source current in dir of vx pos to neg -
can the voltage across an inductor be discontinuous? - Answers yes, v = L*di/dt, if i(t) has a corner
then the voltage will be discontinuous at that point
can the current through an inductor be discontinuous? - Answers no, v = L*di/dt, if i(t) is
discontinuous the voltage will be infinite, which is physically impossible.
can the voltage across a capacitor be discontinuous? - Answers no, I(t) = c*dv/dt, if v(t) is
discontinuous the current will be infinite, which is physically impossible
can the current through a capacitor be discontinuous? - Answers yes, I(t) = c*dv/dt, if v(t) has a
corner then the current will be discontinuous at that point.
dialectric - Answers what separates a pair of conducting plates (capacitor)
e.g. air, mylar, tantalum, ceramic, titania
maxwells law - Answers q(t) = c*v(t)
conduction current - Answers the type of current that flows in wires
displacement current - Answers the type of current that flows between the plates of a capacitor
energy stored/absorbed/delivered in a capacitor - Answers w(t) = c* 1/2 * v^2
energy delivered: w(t1) - w(t2)
energy absorbed: w(t2) - w(t1)
energy stored is always non negative
energy stored: w(t2) = energy stored at t = t2
Rth = - Answers Voc/isc
RC switch circuit t<0 and t-> inf - Answers DC circuit in S.S. therefore C is an open circuit
open circuit - Answers current is zero
voltage divsion - Answers source * (resistor(s) in parallel w source / resistor + other resistors in series)
Tau for RC switch circuits - Answers tau = Rth*C
RL switch circuit t<0 and t-> inf - Answers DC circuit in S.S. therefore L is a short circuit
current division - Answers source * (1/resistor(s) w current aka in series w L) / (1/resistor(s) + 1/other
resistors in parallel)
Tau for RL Switch Circuits - Answers L / Rth
short circuit - Answers v = 0
v(t) given as equation, Ix(t) = ? - Answers ix(t) = C * dv/dt + V/R (if there's a resistor)
capacitors: I(t) and w(t) - Answers I = C * dv/dt
w = C * 1/2 * v^2
inductor - Answers v = L * di/dt
w = L * 1/2 * I^2
trig identity for sin to cos - Answers sin(a) = cos(a - 90)
RL switch circuits iL(t)= - Answers = iL(inf) + [iL(0) - iL(inf)]*e^(-t/tau)
RC switch circuits vC(t)= - Answers = vc(inf) + [vc(0) - vc(inf)]*e^(-t/tau)
RL ix pos/neg - Answers current:
same dir -
opposite dir +
voltage:
current in dir of source pos to neg +
current in dir of source neg to pos -
RC vx pos/neg - Answers voltage:
matching signs +
switched signs -
current:
source current in dir of vx neg to pos +
source current in dir of vx pos to neg -
