comparing DC to ac Flashcards
In a direct current (DC) circuit, current flows in the same direction, but in an alternating (AC) circuit, current changes direction periodically.
true
The biggest single advantage of AC is that it can be ? from one voltage to another.
transformed
? voltages are better for transmitting electricity over long distances.
higher
A higher voltage can be used to transmit the same amount of power at a(n) ? current value.
lower
The power loss (I2R) of a transmission line can be reduced by either decreasing the resistance of the wire or decreasing the amount of current.
true
Reducing the resistance of the wire by one-half will reduce power loss to 25%, but reducing the current by one-half will reduce the power loss to 50%.
false
When attempting to lower power loss by reducing current, ? must be raised by the same proportion to deliver the same amount of power to the user.
voltage
AC is raised from one level of voltage for transmission and then reduced to a different level of voltage for utilization by using ?
transformers
Using higher voltages to transmit electricity allows the use of ? wire.
smaller
The AC voltage waveform is in the positive direction for some period of time, and in the negative direction for some period of time. The name given to this waveform is the ? wave.
sine
Each complete revolution (360° travel) of the loop of wire in an AC generator is called a(n) ?
cycle
Each time the voltage reverses polarity, the current flow through the circuit changes ?
direction
At how many points along a complete (360°) sine wave will the voltage be equal to zero?
3
At what point is the voltage on a sine wave maximum positive?
90
Sine waves are so named because the voltage at any point along the waveform is equal to the maximum (peak) value ? the sine of the angle of rotation.
multiplied by
