Direct and Alternating Current
Physics ⇒ Electricity and Magnetism
Direct and Alternating Current starts at 9 and continues till grade 12.
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Define the term 'root mean square (RMS) value' in the context of alternating current.
Describe one advantage and one disadvantage of using AC over DC.
Describe the function of a rectifier in an electrical circuit.
Explain the main difference between direct current (DC) and alternating current (AC).
A generator produces an AC voltage described by V(t) = 100 sin(314t) V. What is the frequency of the AC voltage?
Which device is used to convert AC to DC?
(1) Transformer
(2) Rectifier
(3) Inductor
(4) Capacitor
Which of the following best describes direct current (DC)?
(1) The current flows in one direction only
(2) The current reverses direction periodically
(3) The current has a sinusoidal waveform
(4) The current has no direction
Which of the following devices can store direct current for later use?
(1) Transformer
(2) Battery
(3) Generator
(4) Inductor
Which of the following is a disadvantage of using DC for power transmission?
(1) High energy loss due to resistance
(2) Difficulty in changing voltage levels
(3) Both (1) and (2)
(4) None of the above
Which of the following is NOT a typical application of direct current?
(1) Charging batteries
(2) Powering household lights
(3) Running electronic devices
(4) Electroplating
Which of the following is true for the direction of current in a DC circuit?
(1) It changes periodically
(2) It remains constant
(3) It is random
(4) It depends on the load
Which of the following statements about transformers is correct?
(1) Transformers work with both AC and DC
(2) Transformers only work with AC
(3) Transformers only work with DC
(4) Transformers convert DC to AC
Fill in the blank: The average value of a pure sinusoidal AC current over one complete cycle is ______.
Fill in the blank: The device used to convert DC to AC is called a(n) ______.
Fill in the blank: The SI unit of electric current is ______.
The frequency of the standard AC supply in most countries is ______ Hz.
State whether the following statement is true or false: Alternating current (AC) can be easily transformed to different voltages using a transformer.
State whether the following statement is true or false: The average power delivered by an AC source is half of the maximum power.
State whether the following statement is true or false: The direction of current in an AC circuit changes periodically.
State whether the following statement is true or false: The peak value of an AC voltage is always equal to its RMS value.
