Unit conversion

• What is the standard unit for electrical power?

  Watts (W)
• Why is it necessary to state measurements with units?

  To ensure clarity and accuracy in the measurements
• What happens to the size of a measurement when it is converted into a different unit?

  The size of the measurement remains the same
• How do you convert 50 mA to amperes?

  50 mA = 50 × 0.001 A = 0.05 A
• How is electrical power calculated?

  By multiplying current by voltage
• What is the power when a 50 mA current passes through a 230 V light bulb?

  11.5 W
• What is the formula for calculating electrical power?

  Power = current × voltage
• What is the power when a 12 mV LED has a current of 0.02 A passing through it?

  0.24 mW
• Why might a measurement need to be converted into the SI equivalent?

  To be useful for calculations
• How do you convert hours into seconds for calculations?

  1 hour = 60 × 60 = 3,600 seconds
• How is electrical energy calculated?

  By multiplying power by time
• What is the energy transferred by a 35 W light bulb when it is on for four hours?

  504,000 J
• What is the standard unit for energy?

  Joules (J)
• How do you calculate the energy transferred when power is in watts and time is in seconds?

  Energy = power × time
• What are the steps to convert a measurement expressed with a prefix back to standard form?

  • Identify the prefix
  • Multiply by the corresponding power of ten
  • Use the standard unit for calculations
• What are the key concepts of unit conversion in physics?

  • SI units
  • Multiple and sub-multiples of units
  • Conversion between different units
  • Importance of significant figures