Final answer:
Power in physics is measured in watts and represents the rate of energy transfer. Calculations for power absorbed or supplied involve different formulas depending on the context, like photoelectric effects or electrical circuits. Conservation of energy principles dictates that in circuits, the power supplied must equal the total power dissipated by the resistors.
Step-by-step explanation:
The formula for power, which is the rate at which energy is absorbed or supplied, is given in watts (W) in the SI system, representing energy per unit time, or joules per second (J/s).
Finding the Power Absorbed or Supplied by Elements
In physics problems, such as those involving photoelectrons or electrical circuits, we use various formulas to calculate the power absorbed or supplied. For example, from a 1.00-mm² area of sodium metal exposed to 500-nm electromagnetic (EM) radiation with an intensity of 1.30 kW/m², we can calculate the number of photoelectrons ejected per second and the power they carry away, considering the binding energy of 2.28 eV.
Electrical Power in Circuits
In the context of electrical circuits, power is calculated using the formula P = IV, where I is the current and V is the voltage. In a circuit with multiple resistors, the total power supplied by the source is equal to the sum of the powers dissipated by the resistors (conservation of energy). This is represented as P1 + P2 + P3 = total power, and in an example could be 0.360 W + 2.16 W + 4.68 W = 7.20 W.