49 Questions
What is the primary advantage of using an auto-transformer?
It allows for voltage transformation using a single winding.
In an auto-transformer with an adjustable tap, what is the purpose of the movable tap?
To provide a variable-output voltage within the transformer's range.
If a voltage of 200 V is applied between points B and C in the auto-transformer schematic, what voltage would be available from points A and B?
100 V
What voltage would be available from points A and C in the auto-transformer schematic if 200 V is applied between points B and C?
300 V
What is the relationship between the voltage across the secondary winding and the voltage across the primary winding in an auto-transformer?
The secondary voltage has the same relationship to the primary voltage as if they were two distinct windings.
Which of the following statements about auto-transformers is correct?
Auto-transformers can only be used at frequencies above their normal operating frequency.
What is the purpose of a Variac auto-transformer?
To provide a variable-output voltage within the transformer's range.
In the auto-transformer schematic, if the tap is at point A, how will the secondary voltage (Es) compare to the primary voltage (Ep)?
Es will be less than Ep.
In the auto-transformer schematic, if the tap is at point B, how will the secondary voltage (Es) compare to the primary voltage (Ep)?
Es will be greater than Ep.
What type of wave can be generated by processing a square wave through an integrator?
Triangular wave
In electronics, how is integration achieved to generate a triangular wave?
By charging and discharging capacitors
What mathematical function describes one function being affected by another, as seen in integration?
Calculus
If acceleration is integrated over time, what physical quantity does it give?
Velocity
When an AC sinusoidal voltage is applied across a resistor, what type of current will flow?
Sine wave current
How is integration achieved in mathematics?
Through the use of calculus
In what way does an integrator process a square wave to create a triangular wave?
Through mathematical function manipulation
What method is used to achieve integration in electronics for generating triangular waves?
Charging and discharging capacitors
Which waveform has equal rise and fall times?
Triangular wave
What is the identifying feature of a sawtooth wave?
Different rise and fall times
Which waveform is generated by a simple on/off switch at low frequencies?
Square wave
What type of wave is used as the clock signal in modern computer processors?
Square wave
How is a simple sawtooth wave generated?
By rapidly charging and discharging a capacitor
What is the primary difference between a triangular wave and a sawtooth wave?
The timing of the rise and fall periods
Which waveform has a smooth, continuous curve?
Sine wave
What is the maximum frequency of a square wave that can be generated using a simple on/off switch?
Limited by the switch speed
In a purely capacitive circuit, the current:
Leads the voltage by 90°
If the load is purely inductive, the current will:
Lag the voltage by 90°
The amount of shift between voltage and current is referred to as:
Phase angle
When an alternating current is connected across an inductor, the inductor has an effect on the circuit similar to that of a:
Resistor
Which of the following statements is true about phase relationships in AC circuits?
Phase relationships depend on circuit components
In a purely capacitive circuit, the phasor representing current is drawn:
90° anti-clockwise from the voltage phasor
What is the phase angle between current and voltage if the load is purely resistive?
0°
In an AC circuit with both inductive and capacitive components, the phase angle between current and voltage:
Depends on the relative values of inductance and capacitance
What is the phase angle between the circuit current (IT) and the applied voltage in the LCR circuit?
36.85 degrees
How is the phase angle calculated in a series LCR circuit?
tan θ = (VC - VL) / VR
What determines whether the phase angle of a circuit is leading or lagging in a phasor diagram?
Polarity of the X-axis voltage
In a series LCR circuit, what does SOH-CAH-TOA help determine?
Phase angle of the applied voltage
What is the relationship between the circuit current (IT) and the resistor voltage (VR) in a series LCR circuit?
IT is in phase with VR
What significance does the frequency of the applied voltage have on circuit values?
Affects phase angle calculation
How is the phase difference represented between the circuit current (IT) and the resistor voltage (VR) in a phasor diagram?
-36.85 degrees
What role does Tan θ play in determining the circuit's phase relationships in a series LCR circuit?
Helps find phase angle between voltages
When a switch is initially closed in a circuit with an inductor and resistor connected in series to a DC power source, what happens?
There will be no current flow initially due to the inductor opposing any change in current.
What happens to the back EMF induced in the inductor after the initial instant when the switch is closed?
The back EMF reduces, allowing the current to increase.
According to Kirchhoff's voltage law, what is the relationship between the voltage drops across the inductor ($V_L$) and resistor ($V_R$) and the supply voltage ($V_s$) at any instant?
$V_L + V_R = V_s$
When inductors are connected in series, what happens to the total inductance?
The total inductance is the sum of the individual inductances.
When inductors are connected in parallel, what happens to the total inductance?
The total inductance is the reciprocal of the sum of the reciprocals of the individual inductances.
What is the formula used to calculate the total inductance of inductors connected in series?
$L_{total} = L_1 + L_2 + \ldots + L_n$
What is the formula used to calculate the total inductance of inductors connected in parallel?
$\frac{1}{L_{total}} = \frac{1}{L_1} + \frac{1}{L_2} + \ldots + \frac{1}{L_n}$
If two inductors of $5$ mH and $10$ mH are connected in parallel, what is the total inductance?
$3.33$ mH
Learn about techniques to minimize losses in electric transformers like reducing wire resistance and considering weight and physical dimensions. Discover how reversing the magnetism of a transformer's core results in hysteresis losses releasing energy as heat.
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