4.2.4 Power

• What is the definition of power in physics?

  Rate of energy transfer
• Power is defined as the energy used divided by the time
• Match the power formula with its variables:

  $P =$$\frac{E}{t}$ ↔️ Power (P), Energy (E), Time (t)

  $P =$$VI$ ↔️ Power (P), Voltage (V), Current (I)

  $P =$$I^{2} R$ ↔️ Power (P), Current (I), Resistance (R)
• Power is measured in watts (W).


  True
• In the power formula $P =$$\frac{E}{t}$, the variable $P$ represents power
• The formula for power in terms of energy and time is $P =$$\frac{W}{t}$
• Which formula relates power, voltage, and current?

  $P =$$VI$
• Order the variables in the power formula from their symbols to their full names:

  1️⃣ $P$

  2️⃣ Power

  3️⃣ $W$

  4️⃣ Energy

  5️⃣ $t$

  6️⃣ Time
• Which formula relates power, voltage, and current?

  $P =$$VI$
• Energy is measured in joules.

  True
• The symbol for energy is E
• What is the formula for power using current and resistance?

  $P =$$I^{2} R$
• What is the definition of power in terms of energy and time?

  Energy used divided by time taken
• The unit of power is the watt, which is equivalent to joules per
• Power is the rate of energy transfer
• The formula for power in terms of energy and time is P = \frac{E}{t}
• A heater transfers 12000 joules of energy in 2 minutes. Its power is 100 watts.
• The power formula $P =$$\frac{E}{t}$ is used when energy and time are known
• What is the power of a light bulb that uses 60 joules of energy every second?

  60 watts
• The unit of power is the watt (W).


  True
• What is energy measured in when using the power formula?

  Joules (J)
• The formula to calculate power using current and resistance is $P =$$I^{2} R$
• What is one watt equivalent to in terms of joules and seconds?

  $\frac{J}{s}$
• What is the formula for power in terms of energy and time?

  $P =$$\frac{E}{t}$
• Match the variable with its unit:

  Power ↔️ Watts

  Energy ↔️ Joules

  Time ↔️ Seconds

  Voltage ↔️ Volts

  Current ↔️ Amperes
• Energy is measured in joules
• A light bulb using 60 J of energy in 10 seconds has a power of 6 watts.


  True
• One watt of power is the transfer of 1 joule of energy in 1 second.


  True
• What is the unit of time in physics?

  Seconds (s)
• What does the formula $P =$$VI$ represent?


  Power in terms of voltage and current
• What is the power of an electrical device that operates at 240 volts and draws a current of 0.5 amps?

  120 watts
• When is the power formula $P =$$VI$ used?


  When voltage and current are known
• Power is measured in watts
• What is another formula for power using voltage and current?

  $P =$$VI$
• One watt is equivalent to one joule per second.


  True
• Power is the rate at which energy is transferred or converted.


  True
• What is the relationship between power and joules per second?

  1 watt = 1 joule per second
• What is the unit of energy?

  Joules (J)
• A light bulb that uses 60 joules of energy in 10 seconds has a power of 6 watts.

  True
• The formula $P =$$I^{2} R$ calculates power dissipated by a resistor.


  True