A(n) __________ is a graph showing how an electrical value changes over a period of time.
WAVEFORM Ref: 1.09
The ac waveform is called a(n) __________ wave.
SINE Ref: 1.14
Frequency is the number of __________ an electrical system goes through in a unit of __________.
CYCLES; TIME ...
203 TRANSFORMERS AND AC CIRCUITS
A(n) __________ is a graph showing how an electrical value changes over a period of time. - correct answer WAVEFORM Ref: 1.09
The ac waveform is called a(n) __________ wave. - correct answer SINE Ref: 1.14
Frequency is the number of __________ an electrical system goes through in a unit of __________. - correct answer CYCLES; TIME Ref: 1.19
In what unit is frequency measured? - correct answer HERTZ (Hz) Ref: 1.20
The number of cycles generated in one complete revolution of an alternator equals half the number of __________. - correct answer POLES Ref: 1.27
What is the frequency of the output of a four-pole alternator running at 1800 revolutions per minute? - correct answer 60 Hz Ref: 1.28 to 1.31
Do motors running on 50 Hz run faster or slower than motors running on 60 Hz? - correct answer SLOWER Ref: 1.35
Peak-to-peak value is defined as the distance from the ___________ point on a waveform to the___________ point. - correct answer MAXIMUM; MINIMUM Ref: 1.40
An ac source is said to be __________to a dc source if they both produce heat in a resistor at the same rate. - correct answer EQUIVALENT Ref: 1.45
The RMS value of potential difference always equals __________ times the amplitude. - correct answer 0.707 Ref: 1.48
Any variation in the __________ in a conductor produces a change in its magnetic field. - correct answer CURRENT Ref: 1.50 Any change in the magnetic field surrounding a conductor induces a(n) __________ across the conductor. - correct answer POTENTIAL DIFFERENCE Ref: 1.52
The potential difference induced across a coil depends on the __________ in the coil and on the rate that the __________ changes. - correct answer NUMBER OF TURNS; MAGNETIC FIELD. Ref: 1.53
Ohm's law says that the __________ in a conductor is proportional to the ___________ across it. - correct answer CURRENT; POTENTIAL DIFFERENCE Ref: 1.56
You can apply all the dc rules and laws to an ac circuit if the circuit contains only ___________. - correct answer RESISTANCE Ref: 1.61
When you apply dc rules and laws to ac circuits, you must use the ___________ values of ac current and potential difference. - correct answer RMS Ref: 1.62
On a waveform, what is represented along the horizontal axis? a. AC potential difference
b. Current c. DC potential difference d. Time - correct answer d. Time Ref: 1.09
Amplitude is the distance from ___________
a. maximum to maximum b. maximum to minimum c. zero to maximum d. zero to midpoint - correct answer c. Zero to maximum. Ref: 1.17
In a four-pole alternator, the magnetic poles are spaced ___________ apart. a. 90° b. 180° c. 270° d. 360° - correct answer a. 90 degrees. Ref: 1.25
The number of cycles produced in one complete revolution of the rotor in an alternator equals ___________ the number of poles.
a. 0.707 times b. exactly
c. half d. twice - correct answer c. Half. Ref: 1.27
What is the frequency of the output of a two pole alternator running at 6000 rpm? a. 50 Hz b. 60 Hz c. 100 Hz d. 120 Hz - correct answer c. 100 Hz. Ref: 1.28 to 1.31
To find the root mean square, you calculate the square root of the mean of all the squares of a. all individual values b. the amplitude c. the maximum negative values d. the peak-to-peak values - correct answer a. All individual values. Ref: 1.47
The root mean square of potential difference or current for a sine wave is 0.707 times the
a. amplitude b. average value c. maximum negative values d. peak-to-peak value - correct answer a. Amplitude. Ref: 1.48 The importance of an induced potential difference is greatest when the conductor is in the shape of a(n) __________.
a. closed loop b. coil c. open loop d. straight line - correct answer b. Coil. Ref: 1.53
Joule's law says the amount of heat produced in a resistor depends in part on the amount of a. current in the resistor b. frequency of the ac source c. magnetic field produced in resistor d. potential difference across the source rules - correct answer a. Current in the resistor. Ref: 1.56
You can apply all the dc rules and laws to ac circuits if the circuits contain only a. capacitance b. conductance c. inductance
d. resistance - correct answer d. Resistance. Ref: 1.61
In an ac generator, the potential difference depends on the __________ of the conductor and on the __________ at which it moves through the magnetic field. - correct answer SPEED; ANGLE Ref: 2.02
How big is a degree, compared to a full circle? - correct answer 1/360 OF A FULL CIRCLE Ref: 2.04
What two angles mark the beginning and end of a cycle? - correct answer 0°, 360° Ref: 2.05
What does the name "triangle" mean? - correct answer THREE ANGLES Ref: 2.08
The sum of the three interior angles of a triangle always equals ___________. - correct answer 180° Ref: 2.09
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