Calculate Wattage

Essential Question: How do I calculate wattage?

Mastery Objectives:

• SWBAT calculate wattage using amps and volts.

• SWBAT calculate wattage for computer parts to select a power supply.

• SWBAT Recall and use the formula: Watts (P)=Volts (V)×Amps (I)

• SWBAT Understand the real-world applications of watts (e.g., in appliances).

Ohm's Law: https://www.youtube.com/watch?v=HsLLq6Rm5tU 

“Have you ever noticed light bulbs say 60W or 100W? What does that mean?”

• Explain:

  • "Watt" is a unit of power, named after James Watt.

  • In electrical systems, power is how fast energy is used or produced.

Direct Instruction

• Introduce the formula:
  P = V X I
  Where:

  • ( P ) = Power (Watts)

  • ( V ) = Voltage (Volts)

  • ( I ) = Current (Amps)

• Example:

  • If a device uses 2 amps at 120 volts:
    P = 120 X 2 = 240 watts

Guided Practice

• Solve 2–3 problems together:

  • Example 1: A toaster uses 5 A at 110 V. What is the power?
    P = 110 times 5 = 550W
    
    

  • Example 2: A laptop charger outputs 65 W at 19.5 V. What is the current?
    I = P / V = 65 / 19.5 ≈ 3.33,A

5. Independent Practice (10 minutes)