Power is an important idea to know when we talk about how well machines and devices work.

In simple terms, power is how quickly work gets done or how fast energy moves from one place to another. We can show this with a math formula:

$$P = \frac{W}{t}$$

Here, $P$ stands for power, $W$ is the work done, and $t$ is the time taken.

Key Points:

• Efficiency:

Efficiency, written as $\eta$, shows how much useful work comes out compared to the total energy used. We can write it like this:

$$\eta = \frac{W_{\text{out}}}{W_{\text{in}}} \times 100\%$$

• Types of Machines:

  • Electric motors usually work at about 85-95% efficiency.
  • Internal combustion engines, like the ones in cars, are less efficient, usually around 20-30%.

• Power Sources:

  • Solar panels can be about 20% efficient at converting sunlight into energy.

  • Wind turbines, which use wind to create energy, are generally around 35-45% efficient.

By understanding power, engineers can create better systems that use energy more wisely and waste less of it.