Home » 国际课程 » A-level课程 » Details

CIE A Level Physics复习笔记9.1.4 Electrical Power

Category: A-level课程, 教材笔记, 福利干货 Date: 2022年8月16日下午3:47

Calculating Electrical Power

In “Work, Energy and Power”, Power P was defined as the rate of doing work
- Potential difference is the work done per unit charge
- Current is the rate of flow of charge
So, the power dissipated (produced) by an electrical device is defined as:

9.1.2.3-Power-equation

Power of a component in an electrical circuit

Using V = IR to rearrange for either V or I and substituting into the power equation means we also write power in terms of resistance R

9.1.2.3-Power-in-terms-of-resistance

Power equation in terms of resistance

This means for a given resistance for example, if the current or voltage doubles the power will be four times as great

Worked Example

Two lamps are connected in series to a 150 V power supply. WE-power-question-image

Which statement most accurately describes what happens?

A. Both lamps light normally

B. The 15 V lamp blows

C. Only the 41 W lamp lights

D. Both lamps light at less than their normal brightness

ANSWER: A

9.1.2.3-Worked-example-power-2

Exam Tip

You can use the mnemonic “Twinkle Twinkle Little Star, Power equals I squared R” to remember whether to multiply or divide by resistance in the power equationsWhich equation to use will depend on whether the value of current or voltage has been given in the question

转载自savemyexams

以上就是关于【CIE A Level Physics复习笔记9.1.4 Electrical Power】的解答，如需了解学校/赛事/课程动态，可至翰林教育官网获取更多信息。

往期文章阅读推荐：

生物竞赛金牌教练的实战书单！生物学/生物化学/病理学...电子版免费领！

哈佛商学院2026暑期书单曝光！十余位教授私藏书单，本本是“商科天花板”