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T5C11

ELECTRICAL PRINCIPLES · Capacitance and inductance terminology and units; Radio frequency definition and units; Impedance definition and units; Calculating power

T5C11T5C →

How much current is required to deliver 120 watts at a voltage of 12 volts DC?

  1. A0.1 amperes
  2. B10 amperes
  3. C12 amperes
  4. D132 amperes
Why Power in a DC circuit is P = I x E, so current is found by dividing power by voltage: I = P / E. Here 120 watts divided by 12 volts gives 10 amperes. This is one of the three forms of the power wheel, alongside P = I x E and E = P / I.
Watch out The 0.1 ampere choice comes from flipping the division and computing 12 / 120, and 132 comes from simply adding the two numbers, which has no physical meaning.
PIE: P = I x E. Cover the unknown - current equals watts over volts, 120/12 = 10.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
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The rest of T5C

  1. T5C01 What describes the ability to store energy in an electric field?
  2. T5C02 What is the unit of capacitance?
  3. T5C03 What describes the ability to store energy in a magnetic field?
  4. T5C04 What is the unit of inductance?
  5. T5C05 What is the unit of impedance?
  6. T5C06 What is the abbreviation for kilohertz?
  7. T5C07 What is the abbreviation for megahertz?
  8. T5C08 What formula is used to calculate electrical power (P) in a DC circuit?
  9. T5C09 How much power is delivered by a voltage of 13.8 volts DC and a current of 10 amperes?
  10. T5C10 How much power is delivered by a voltage of 12 volts DC and a current of 2.5 amperes?
  11. T5C11 How much current is required to deliver 120 watts at a voltage of 12 volts DC?
  12. T5C12 What is impedance?
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