What increases the resistance of wire at high frequencies?
Temperature
Voltage
Skin effect
Insulation
Correct Answer :
C. Skin effect
Related Questions
Which of the following has a positive temperature coefficient?
Mica
Manganin
Silicon
Carbon
What is the resonant frequency of a circuit when L of 25 microhenrys and C of 10 picofarads are in parallel?
10.1 kHz
10.1 MHz
101 MHz
101 kHz
The power factor of a circuit is equal to
RZ
XC/Z
XL/Z
R/Z
Voltage resonance means
Series resonance
Parallel resonance
Current magnification
Gain magnification
A wire of one kilometre length has a resistance of 20 . If the length is halveda then the new resistance is ___ the original resistance.
Half
Twice
One-fourth
Three times
In dividing or multiplying phasor quantitiesa ___ form is used.
Polar
Rectangular
Trigonometric
Exponential
Which of the following materials has the lowest dielectric strength?
Glass
Paper
Mica
Teflon
An open inductor has
Zero resistance and infinite inductance
Infinite resistance and zero inductance
Infinite resistance and infinite inductance
Zero resistance and zero inductance
Kirchhoff�s laws (KCL and KVL) are applicable to
DCcircuits
ACcircuits
DC as well as AC circuits
Passive networks alone
What is expected when two 20 k a 1 watt resistor in parallel are use instead of one 10 k a 1 watt?
Provides higher current
Provides less power
Provides more power
Provides wider tolerance
The distance between the capacitor plates increases two timesa then its capacitance
Increases two times
Increases four times
Decreases two times
Decreases four times
In adding or subtracting phasor quantitiesa ___ form is the most convenient.
Polar
Rectangular
Trigonometric
Exponential
A linear circuit is one whose parameters
Change with change in voltage
Change with change in current
Do not change with voltage and current
Change with change in voltage and current
If a coil has a Q of 10a it means that
The energy stored in the magnetic field of the coil is 10 times the energy wasted in its resistance
The energy wasted in its resistance is 10 times the energy stored in the magnetic field of the coil
It is a low Q coil
It is a high Q coil
Thevenin�s theorem is what form of an equivalent circuit?
Current
Voltage
Both current and voltage
Neither current nor voltage
A real current source has
Infinite internal resistance
Zero internal resistance
Large internal resistance
Small internal resistance
The temperature coefficient of resistance of electrolytes is
Negative
Positive
Zero
Infinite
What rating of a resistor determines its ability to absorb heat?
Wattage
Ohmic
Current
Voltage
If the output resistance of a voltage source is 4 a it internal resistance should be
Infinite
The internal resistance of an ideal current source is
Infinite
Zero
Equal to the load resistance
To be determined
In a resonant circuita if Q ? 10 resonant frequency _______ bandwidth.
Bisects
Exceeds
Is less than
Is equal to
An inductive load always has a ___ power factor
Leading
Lagging
Zero
Unity
Which of the following is a way of decreasing mutual inductance?
Moving the coils closer
Moving the coils apart
Decreasing the number of turns of either coil
Increasing the number of turns of either coil
In an ac circuit with a resistive branch and an inductive branch in parallela the
Voltage across the inductance leads the voltage across the resistance by 90°
Resistive branch current is 90° out of phase with the inductive branch current
Resistive and inductive branch currents have the same phase
Resistive and inductive branch currents are 180° outof-phase
Which of the following is a common material used in wire-wound resistors?
Manganin
Carbon
Bronze
German silver wire
The capacitor opposes any change in voltage across it by
Passing a voltage proportional to the rate of change of current
Acting as a short circuit at time equal to zero
Passing a current proportional to the rate of change of voltage
Acting as a short circuit at time equal to infinity
What dielectric is generally employed by a variable capacitor?
Mica
Air
Electrolyte
Ceramic
Transient period is considered over after
The ratio between the active power and the apparent power of a load in an ac circuit is called
Quality factor
Power factor
Power ratio
Power reactive
When current and voltage arte in phase in an ac circuita the ___ is equal to zero.
Resistance
Reactance
Inductance
Capacitance