what is the cap of this cap
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Chapter 1 Ancient Greek Culture1.How did Zeus punish Prometheus for stealing fire from him?【宙斯如何惩罚盗火的普罗米修斯?】P 6Prometheus was chained to a mountain ,an eagle would devour his liver ,and his liver would grow out the next day before the eagle came to devour it again.(普罗米修斯被锁链锁在一座山上,他的肝脏被一只鹰吞噬,而他的肝脏又会在第二天,那只鹰来吃之前长出来)2.What does the phrase “Achilles’ heel” refer to?【“阿基里斯之踵”指的是什么呢?】P 12Achilles is the bravest and strongest of the Greek warriors in the Trojan War,and his heel is his only weakness,now use the word Achilles’ heel to describe ones only weakness.(阿基里是特洛伊战争中一个最勇敢最强壮的战士,后脚跟是他唯一的缺点,现在用这个词来形容一个人唯一的缺点)3.What is the name of the mountain where the ancient Greeks believed their gods lived?【古希腊人认为他们的神住在哪座山上?】P 6Mount Olympia (奥林匹亚山)4.Who is the god of the underworld?【阴间的神是谁?】P 8Hades(哈迪斯——冥王)5.Which battle in ancient Greece started from the apple of discord?【古希腊开战的祸根?】P13The Trojan War(特洛伊战争)6.What are the primary symbols of the sea god Poseidon?【海神波塞冬的主要标志?】P 8His weapon,trident(他的武器,三叉戟)7.What is the psychological term coined by Sigmund Freud based on the Greek mythological character Oedipus?【什么心理学词汇是西格蒙德·弗洛伊德根据希腊神话人物俄狄浦斯所创造的?】P 14Oedipus complex(恋母情结)8.Who was considered by Aristotle to be the first philosopher in Greek tradition? 【谁是亚里士多德认为的希腊传统上第一位哲♂学家】P 15Thales(泰利斯)9. In Greek mythology,Prometheus普罗米修斯made human beings out of clay(粘上), taught man how to survive in the harsh(严酷的)environment and stole fire from heaven for the benefit of man.10.Apollo 阿波罗is the sun-god and the god of music and poetry.11. Artemis(阿耳特弥斯), also known as Diana戴安娜, is the goddess of moon, wild animals, the hunt, vegetation, chastity and childbirth.12. Athena雅典娜is the goddess of war, handicraft and wisdom.13. Aphrodite阿佛洛狄忒is the goddess of beauty and love, better known by her Roman name Venus维纳斯.14. Eros is the son of Venus, better known by his Roman name Cupid丘比特_.15. Hermes赫尔墨斯is the god of thieves(蒂费斯小偷), travelers and merchants. He is often depicted with a pair of winged sandals有翅膀的凉鞋哈哈哈and a winged cap(有翅膀的帽子看上去好傻啊哈哈哈),which enable him to travel swifter than sight.16. Identify who each of the following descriptions is referring to. P 14-221) The greatest of ancient Greek epic poets, he is the author of the 'Iliad' and 'Odyssey'. (这个人是古希腊的伟大诗人,写过《伊利亚特》和《奥德赛》)B.荷马不是河马2) This philosopher was the teacher of Alexander the Great and set up h is own school---named---Lyceum.(这个人担任过亚历山大大帝的老师,还建立了“学会”)A.亚里士多德3) For this philosopher everything was related to mathematics and numbers were the ultimate reality. He influenced Plato and discovered a theorem that was named after him. D.毕达哥拉斯_4) This philosopher was the teacher of Plato and the protagonist of Plato’s dialogues. _E.苏格拉底5) This philosopher and student of Socrates founded the Academy in Athens, the first institution of higher learning in the Western world.C.柏拉图A. AristotleB. HomerC. PlatoD. PythagorasE. SocratesChapter 3 Food1.What can the word “salad” mean? And the phrase “salad days”?【“沙拉”是什么?“沙拉时光”又是什么?】P77Salad,a mixture of foods,consisting of chopped vegetables,meat,seafood and so on.Salad days, means a youthful time.(沙拉是一种混合食物,包含了切碎的菜,肉,海鲜之类的;沙拉时光指的是年轻的岁月)2.When can salad be served during a meal?【沙拉可以在那一餐上吃呢?】P78Salads may be served at any point during a meal(沙拉在什么时候都可以吃)3.Can you name some kinds of salad and explain them? What is the difference between green salads and vegetable salads?【你能举一些沙拉品种的例子并且解释它们吗?绿色沙拉和蔬菜沙拉有什么区别吗?】P78Side salads,a kind of side dish;Entree salads,as the main dishes.We can add some meat, fish in green salads, but not in vegetables salads.(配菜沙拉,一种配菜;主菜沙拉,充当主菜;我们可以在绿色沙拉里面加鱼加肉,但不在蔬菜沙拉中加)4.What are salad dressings? What are the three basic types of salad dressing applied in Western culture? Please give some examples of each type.【沙拉酱是什么?西方文化中的三大主要沙拉酱是什么?请举例】P79They are sauces for salads.The three basic types of salads dressing are vinaigrette,creamy dressing and cooked dressing.(他们是沙拉的酱汁。
批判性思维的重要性与如何崇拜的英语作文全文共3篇示例,供读者参考篇1The Power of Questioning Everything: Why Critical Thinking MattersHave you ever wondered why things are the way they are? Or why people believe certain things to be true? Well, that's what critical thinking is all about – questioning ideas, facts, and opinions instead of just accepting them at face value. Critical thinking is like a superpower that allows you to see the world from different angles and make well-informed decisions. Let me explain why it's so important and how you can become a master of critical thinking yourself!Why Critical Thinking is AwesomeIt helps you spot fake news and lies.In today's world, there's a lot of misleading information floating around, especially on the internet and social media. With critical thinking skills, you can learn to question the sources of information, look for evidence, and separate fact from fiction.This way, you won't be easily fooled by rumors, propaganda, or "fake news."It makes you a better problem-solver.Life is full of challenges and problems that need solving. Critical thinkers don't just accept the first solution that comes along. They explore different options, weigh the pros and cons, and come up with creative and effective solutions. This skill is valuable in school, at home, and in pretty much every aspect of life.It helps you understand different perspectives.Critical thinking encourages you to consider multiple viewpoints and perspectives, even if they're different from your own. This helps you become more open-minded, empathetic, and respectful of others' beliefs and cultures. It's a crucial skill for getting along with people from diverse backgrounds.It boosts your confidence and independence.When you rely on critical thinking, you're not just blindly following what others say or believe. You're forming your own opinions based on evidence and reasoning. This buildsself-confidence and independence, allowing you to trust your own judgment and decisions.How to Become a Critical Thinking NinjaNow that you know why critical thinking is so awesome, let's talk about how you can develop this skill. Here are some tips:Ask questions, lots of them!The first step to critical thinking is to cultivate a curious mindset. Don't be afraid to ask "why" or "how" questions, even if you think they might sound silly. Questioning things is how you learn and grow.Look for evidence and reliable sources.When someone makes a claim or states a fact, don't just accept it at face value. Ask for evidence or look for reliable sources that back up the information. Good sources include books, reputable websites, and experts in the field.Consider different perspectives.Try to look at situations from multiple angles and viewpoints. How might someone else see or experience the same thing? Understanding different perspectives helps you think more critically and make more informed decisions.Challenge your own assumptions.We all have beliefs and assumptions that we've picked up from our families, friends, or society. But critical thinkers are willing to challenge their own assumptions and beliefs when presented with new evidence or perspectives.Practice, practice, practice!Critical thinking is a skill that takes time and practice to develop. So, start applying these strategies in your everyday life – when you're doing homework, watching TV, or even playing games with friends. The more you practice, the better you'll get!Real-Life Examples of Critical ThinkingLet's look at some real-life examples of how critical thinking can be useful:Example 1: You see an advertisement for a new toy that claims to be "the best toy ever!" Instead of believing the ad right away, a critical thinker would ask questions like:What makes this toy better than others?Is there evidence or reviews to support the claim?Who made the advertisement, and what's their motive for saying it's the best?Example 2: Your friend tells you that a certain celebrity is a "horrible person" because they read something negative about them online. A critical thinker might respond:What's the source of that information? Is it reliable?Have you considered other perspectives or facts about this person?People can make mistakes, but does one negative thing make someone a "horrible person"?Example 3: In science class, your teacher explains how plants get energy from the sun through photosynthesis. A critical thinker might wonder:How do we know this is true? What's the evidence?Are there any other theories or explanations for how plants get energy?Can I find more information or conduct an experiment to better understand this process?As you can see, critical thinking helps you question information, consider multiple viewpoints, and makewell-reasoned decisions based on evidence. It's a powerful toolthat can serve you well in school, in your relationships, and throughout your life.So, the next time someone tells you something or tries to convince you of something, don't just accept it blindly. Put on your critical thinking cap and ask questions, seek evidence, and form your own opinions. You'll be amazed at how much more you'll learn and understand by embracing the power of critical thinking!篇2The Power of Questioning Everything: Why Critical Thinking MattersHave you ever been told something by an adult or read something in a book and thought to yourself "But how do they know that's true?" I have those kinds of thoughts all the time! I'm the kid who is always asking "Why?" and sometimes driving my parents and teachers a little crazy with all my questions. But you know what? I think asking questions and thinking critically is one of the most important things we can do. Let me explain why.Critical thinking means not just believing everything you hear or read, but questioning it. It means diving deeper, looking at sources, considering different perspectives, and then formingyour own opinion or conclusion based on logic and evidence rather than just blindly accepting what you're told. Does that make sense?The opposite of critical thinking is just passively accepting everything at face value without questioning it at all. But if we all did that, we'd believe everything we saw on TV commercials about which sugary cereal is the best! We'd believe every crazy conspiracy theory our silly uncle shares on social media. We might even end up believing things that are clearly silly and untrue, like the earth being flat or that licking a frozen metal pole in winter gives you superpowers.Thinking critically helps us see through lies, resist manipulation, and form beliefs grounded in facts and reason rather than rumor or faulty logic. That's a powerful skill to have! I don't know about you, but I don't want to go through life being fooled and tricked all the time.Let me give you an example of critical thinking in action. Let's say you read online that a certain type of fruit suddenly causes infertility and makes people sick. Your first instinct might be to panic and avoid that fruit entirely. But by using critical thinking skills, you would instead ask:What is the source of this claim? Is it a respected medical journal or just some rando blogger?What evidence are they providing that this fruit is dangerous? Have there been real scientific studies?Could there be any other explanation for why some people felt sick after eating that fruit?What do other experts and nutritionists say about the safety of this fruit?By digging deeper and looking at it from all angles instead of just blindly believing the initial claim, you are much more likely to end up with an accurate and well-reasoned understanding. Maybe it turns out there was just a bad batch of that fruit but overall it's perfectly safe. Or maybe there is a legitimate risk, but only for certain at-risk groups. Critical thinking provides you with a way to find the truth.Thinking critically has all kinds of benefits beyond just not getting tricked. It helps us learn more deeply by constantly questioning and analyzing what we're taught rather than just memorizing facts. It helps us become better problem solvers by thoroughly examining issues and weighing potential solutions. It makes us better decision makers in all areas of life.And you know what? It actually makes us smarter over time! Studies show that kids who are taught critical thinking skills in school have better memory, better reading comprehension, and perform better academically overall. How cool is that? Just by constantly asking "Why?" we are giving our brains an awesome workout.I know some people think constantly doubting and questioning everything is annoying or disrespectful. But in my opinion, there's nothing more respectful than using your brain to its full potential. We shouldn't just blindly accept everything adults and authority figures tell us. We should analyze it, discuss it, and decide for ourselves if it rings true. That's the road to growing up into an independent, free-thinking adult!Of course, taken too far, overly doubting everything including obvious facts can become a problem. We have to use our critical thinking skills along with common sense. For example, I'm not going to spend hours questioning whether the earth is round or if 2+2 really equals 4. Some things are so thoroughly established through evidence that we can accept them as basic truths.But for everything else — stuff we learn in school, information in the news, claims made by politicians orcompanies trying to sell us stuff — I think a healthy dose of critical thinking is crucial. Don't you?So how can you become a more critical thinker? Here are some tips:Always ask questions! Why is something true? What's the evidence? Are there other possible explanations? This simple habit will get your critical thinking gears turning.Don't just accept everything at face value. When you encounter a claim or someone's opinion, explore it from multiple angles before deciding if you agree.Look for trusted, reliable sources. Just because something is on the internet or you heard it from a friend doesn't make it accurate. Learn to identify experts and credible sources.Consider different perspectives. Just because you initially agree with something doesn't mean you shouldn't critically analyze it from other viewpoints too.Use logic and reasoning. If someone's argument has holes, flaws, or contradictions in it, point those out! Solid logic should back up any conclusion.Be willing to change your mind. Critical thinkers remain open to revising their opinions and beliefs when presented with new and compelling evidence that contradicts them.Practice on everything! Critical thinking isn't just for academics. Apply these habits to movies you watch, stories you read, stuff you see on social media, anything!I know it can feel weird or uncomfortable at first to constantly question things, especially when it comes to adults and authority figures. You might get accused of being a "smart aleck" or told to quit arguing. But in my opinion, being a critical thinker who is always eager to learn and understand deeply is something to be proud of, not embarrassed about!If we all exercise our critical thinking muscles more often, I believe the world will be a better place. We'll be harder to manipulate, trick, or mislead. We'll be able to distinguish fact from fiction. And we'll make smarter choices as individuals and as a society.So next time someone tells you to just accept something on blind faith, don't be afraid to respectfully ask "Why?" Think for yourself, analyze the evidence, and make up your own mind. The ability to think critically is one of the most valuable skills we can develop. It leads to deeper knowledge, better decisions, and aricher understanding of our amazingly complex world. Let's all start flexing those critical thinking muscles today!篇3The Power of Critical ThinkingHave you ever wondered why some people seem to be better at solving problems or making decisions than others? The answer lies in their ability to think critically. Critical thinking is like a superpower that can help you navigate through life's challenges and make the best choices.What is Critical Thinking?Critical thinking is the ability to analyze information objectively and make rational judgments. It involves questioning assumptions, considering different perspectives, and using logical reasoning to draw conclusions. When you think critically, you don't just accept information at face value; instead, you examine it carefully and ask questions like:Is this information accurate and reliable?Are there any biases or hidden agendas?What are the strengths and weaknesses of this argument?Are there alternative explanations or solutions?By asking these kinds of questions, you can avoid being misled by false information or making hasty decisions based on incomplete or biased data.Why is Critical Thinking Important?Critical thinking is essential in almost every aspect of life. Here are just a few reasons why it's so important:Problem-solving: Life is full of problems, big and small. Whether you're trying to figure out how to deal with a bully at school or solve a complex math equation, critical thinking can help you analyze the situation, consider different options, and find the best solution.Decision-making: Every day, we make countless decisions, from what to wear to how to spend our time. Critical thinking helps us weigh the pros and cons of each option and choose the one that aligns with our goals and values.Learning: Critical thinking is essential for effective learning. When you think critically, you don't just memorize information; instead, you understand it deeply and can apply it to new situations.Communication: Critical thinking helps you express your thoughts clearly and persuasively. It also enables you tounderstand and evaluate the arguments of others, leading to more productive discussions and better collaboration.Future success: In today's rapidly changing world, the ability to think critically is highly valued in school, the workplace, and beyond. Employers and educators recognize the importance of critical thinking and seek individuals who can analyze complex issues, solve problems creatively, and adapt to new situations.How to Cultivate Critical ThinkingDeveloping critical thinking skills takes practice, but it's a valuable investment in your personal and academic growth. Here are some strategies to help you become a more critical thinker:Ask questions: Curiosity is the foundation of critical thinking. Don't be afraid to ask questions, even if they seem simple or silly. Questioning helps you understand things better and identify potential flaws or gaps in information.Consider different perspectives: Try to look at issues from multiple angles. Seek out diverse viewpoints and opinions, and try to understand the reasoning behind them. This will broaden your perspective and help you avoid tunnel vision.Challenge assumptions: Don't accept information or beliefs at face value. Question assumptions and examine the evidencesupporting them. Ask yourself, "Why do I believe this?" and "Is there a better explanation or alternative?"Think logically: Practice using logical reasoning to analyze information and draw conclusions. Look for cause-and-effect relationships, compare and contrast ideas, and identify patterns or inconsistencies.Be open-minded: Approach problems and situations with an open mind. Resist the urge to jump to conclusions or dismiss ideas that contradict your existing beliefs. Be willing to change your mind if presented with compelling evidence.Practice, practice, practice: Critical thinking is a skill that requires practice. Look for opportunities to apply critical thinking in your daily life, whether it's analyzing the plot of a book, evaluating the claims in advertisements, or solving puzzles or riddles.Critical thinking is a powerful tool that can help you navigate the complexities of life with greater clarity and confidence. By developing this skill, you'll be better equipped to solve problems, make informed decisions, and achieve your goals. So, embrace the power of critical thinking and watch your potential soar!。
Unit2Lesson2Is this your cap?教学目标:1.能够正确描述衣物。
2.能够听说认读单词cap isn’t。
3.能够运用下列句型谈论衣物的所属关系Is this your cap? Yes, it is. / No,it isn’t.教学重点:运用所学的句型,“Is this your cap?”来询问别人,如:sweater, schoolbag, pen, pencil, ruler 等,来复习所学的词汇。
教学难点:学生能正确读出句子和答句。
“Is this your Cap ?以及答句Yes, it is. /No, it isn’t.教学过程课前交流:T: Now, please look at my eyes. Are you ready? Ss:Yes.T: Class begins.Step1. Warm-up1.Greetings2.Sing a song:Play the flash:the students sing the song《What’s this?》【设计意图】以歌曲开始,把学生带入英语课堂氛围。
并滚动旧知识,将上节课学过的介绍物品进行复现。
3.Free talk:(Everyday English.)【设计意图】每日英语秀,这个环节每节课拿出几分钟让孩子们秀英语,同学们通过pk 激发学习英语的兴趣。
PPt 出示学过的物品的名称。
生问:What’s this?生答:It’s a schoolbag./book,pencil-case,pencil,ruler……描述: I have a new … It’s… It’s cool/lovely. I like it./I love it.Then practice it in pairs(用图片展示毛衣,裙子、帽子、钢笔、铅笔等图片,并让学生用I have a new …的已学句型去介绍自己的所有物,滚动旧知识。
科技英语翻译1.1 翻译的标准第1节翻译练习1The powerplantis the heartof a ship.The powerunit for drivin g the machin es is a 50-hp induct ion motor.动力装置是船舶的心脏。
驱动这些机器的动力装置是一台50马力的感应电动机。
第1节翻译练习2Semico nduct or device s, called transi stors, are replac ing tubesin many applic ation s.Crampe d condit ionsmeansthat passen gers’legscannot move around freely.All bodies are knownto posses s weight and occupy space.半导体装置也称为晶体管,在许多场合替代电子管。
我们知道,所有的物体都有重量并占据空间。
空间狭窄,旅客的两腿就不能自由活动。
第1节翻译练习3The remova l of minera ls from wateris called soften ing.A typica l foliag e leaf of a plantbelong ing to the dicoty ledon s is compos ed of two princi pal parts: bladeand petiol e.去除水中的矿物质叫做软化。
双子叶植物典型的营养叶由两个主要部分组成:叶片和叶柄。
1.2 对译者的要求第4节翻译练习1Einste in’srelati vitytheory is the only one whichcan explai n such phenom ena.All four (outerplanet s) probab ly have coresof metals, silica tes, and water.爱因斯坦的相对论是能解释这种现象的唯一理论。
代词代词是代替名词的一种词类。
大多数代词具有名词和形容词的功能。
英语中的代词,按其意义、特征及在句中的作用分为:人称代词、物主代词、指示代词、自身代词、相互代词、疑问代词、关系代词和不定代词八种。
一、人称代词是表示"我"、"你"、"他"、"她"、"它"、"我们"、"你们"、"他们"的词。
人称代词有人称、数和格的变化,见下表:数单数复数格主格宾格主格宾格第一人称I me we us第二人称you you you youhe him they them第三人称she her they themit it they them如:He is my friend.他是我的朋友。
It's me.是我。
二、物主代词表示所有关系的代词,也可叫做代词所有格。
物主代词分形容性物主代词和名词性物主代词二种,其人物和数的变化见下表。
数单数复数人称第一第二第三第一第二第三人称人称人称人称人称人称形容词性my your his/her its our your/their物主代词名词性mine yours his/hers its ours yours/theirs物主代词如:I like his car.我喜欢他的小汽车。
Our school is here,and theirs is there.我们的学校在这儿,他们的在那儿。
三、指示代词表示"那个"、"这个"、"这些"、"那些"等指示概念的代词。
指示代词有this,that,these,those等。
如:That is a good idea.那是个好主意。
四、表示"我自己"、"你自己"、"他自己"、"我们自己"、"你们自己"和"他们自己"等的代词,叫做自身代词,也称为"反身代词"。
UNIT 1第一单元Lessons 1~6第一~第六课The Clothes We Wear 我们穿的衣服Lesson 1 Skirt and Trousers 第一课 短裙和裤子○1 This is a red skirt. 这是一条红色的短裙我喜欢它。
黄色是我最喜欢的颜色。
衬衫 短裙 裤子 T 恤衫 毛衣 ○2 Let ’s do it! 让我们做! Match and colour. 连线并涂色This is a T-shirt. 这是一件T 恤衫。
It’s red. 它是红色的。
These are trousers. 这些是裤子。
They’re black. 它们是黑色的。
This is a shirt. 这是一条衬衫。
It ’s green. 它是绿色的。
○3What is he/she wearing?他/她穿着什么?He is wearing a green sweater. She is wearing a white T-shirt. 他穿着一件绿色的毛衣。
她穿着一件白色的T恤衫。
He is wearing blue trousers. She is wearing a yellow skirt. 他穿着蓝色的裤子。
她穿着一条黄色的短裙。
○4Let’s play!让我们玩吧!Group work. Listen and guess.分组。
听一听然后猜一猜。
Lesson 2 New and Old第二课新的和旧的○1New or old?新的还是旧的?This is a new sweater. This is an old sweater. 这是一件新毛衣。
这是一件旧毛衣。
These are new trousers These are old trousers. 这是新裤子。
这是旧裤子。
○2Let’s do it!让我们做!Look and write.看看然后写写。
初一上册英语基础知识清单Unit7: How much are these socks询问价格或数量01关于双数词汇02货币单位03提供帮助的服务用语04其他句子05目录CONTENTS询问价格或数量Inquiry for price or quantity"What’s the price of+商品?"句型也是用来询问价格的,这个句型更直接地询问商品的价格。
例如:What's the price of that shirt?(那件衬衫多少钱?)在我们购买商品或者比较商品价格时,这个句型非常实用。
What’s the price of+商品?本单元我们学习了询问价格的句型之一是"How much is+单数商品?",使用这个句型我们可以询问一个商品的价格。
例如:How much is this book?(这本书多少钱?)这种句型在日常生活中很常见,如超市购物,网购等情况都会用到。
How much is+ 单数商品?"How much are +复数商品?",是另一个询问价格的句型。
当我们需要询问多样物品的价格时,我们使用这个句型。
例如:How much are these socks?(这些袜子多少钱?)学会这个句型,能够帮助我们更准确地询问和理解商品的价格。
How much are + 复数商品?询问价格的句型"How many + 可数名词"是询问数量的一个常用方式。
例如:"How many apples do you have?" (你有多少个苹果?) 学习这个句型可以帮助我们理解和询问数量。
"How much + 不可数名词"可以用来询问不可数名词的数量。
例如:"How much water do you want?" (你想要多少水?) 这个句型在日常生活,尤其是在烹饪,购物等环境中使用。
TDK Components USA, Inc.Steve MaloyWhat is the Capacitance of this Capacitor?and answer format readers find most helpful.compensates for this natural phenomena in a question provides an explanation of aging and how TDKdielectric aging and its effect on capacitance. This paper TDK recognizes not all users of MLCCs are aware of AbstractFrequently asked questions regarding aging and its effect on capacitance.MLCC Application NotesWhat is the Capacitance of thisCapacitor?Frequently asked questions regarding aging and itseffect on capacitance.By Steve MaloyQuestion 1 : What is “aging”?Aging is generally referred to as a decrease in capacitance over time in EIA Class II capacitors. It is a natural and unavoidable phenomena that occurs in all ferroelectric formulations used as the dielectric material. Aging is reversible and occurs due to changes in the dielectric’s crystal structure with temperature and time. Aging is typically reported as a percent capacitance loss per decade of time.Because aging is logarithmic in nature, the loss ofcapacitance is greatest in the first 10 hours of age.Figure 1 : Capacitance Aging Characteristic(Taken from the TDK Chip Capacitor Catalog - Document ID:BBE-008B, 04/92)Note : The dissipation factor also ages, decreasing several times faster than the capacitance. And, EIA Class III and IV also exhibit aging characteristics.Industry “official” definitions of aging can be found in EIA-521 and IEC-384-9.Question 2:What is the difference between a Class I capacitor and a Class II capacitor?A Class I capacitor 1(C0G, C0H, C0K, etc.) is made from ceramic materials that are not sensitive to temperature changes, thus the capacitance value of a capacitor measured at a low temperature (example -25°C) will not significantly vary from the same capacitor measured at a higher temperature (ex.75°C). EIA refers to these as “temperature compensating,” and are measured in ppm/°C.These capacitors typically have low capacitance values because of the ceramic material used to manufacture them but they exhibit nearly perfect capacitance stability regardless of their temperature,making them an excellent choice for applications in which frequency control is needed such as in radio or television tuners. An example of such is found below:C0G =±30 PPM over a temperature range of -55~+85°CA Class II capacitor 2 (X7R, Y5V, Z5U) is made from ceramic materials that are derived from a barium titanate base which is temperature sensitive. Thus the various temperature classifications stating the extent of the sensitivity over a given temperature range. These capacitors allow for larger capacitance values in the small surface mount packages.Examples of Class II TemperatureCharacteristics 3are below:X7R = ±15% over a temperature range of-55~+125°CY5V = +22%, -82% over a range of -30~+85°C Z5U = +22%, -56% over a range of +10~+85°C Additionally, capacitors made from barium titanate bases (Class II, III, and IV) are ferroelectric and therefore susceptible to “aging” in which a capacitor’s ability to hold capacitance will decrease over time if left in an unheated and/or uncharged state. Class I capacitors are not ferroelectric and therefore do not age.Question 3:Why and how do capacitors of barium titanate age?Over time the internal molecular structure changes in such a way as to create an alignment of electrical dipoles. This alignment results in a molecular structure that can hold less electrical charge than when the molecules are in a totally random state, such as at the time of heating or mounting (soldering) on a printed circuit board.4Figure 2 : Alignment of Electric dipoles Question 4 : What is de-aging?De-aging is a heat treatment used to reset the aging phenomena. Simply put, it restarts the aging process, but it does not prevent it. Heating the capacitor above its Curie Temperature causes the crystalline structure to return to its optimum unaligned configuration resulting in maximum capacitance. TDK recommends 150°C/1 hour for de-aging. Note : It is important to record the time of last heat (TOLH), or de-aging time, for future capacitance measurements.Question 5:Is “aging” just a TDK phenomena?No. The “aging” that is observed is common to all manufacturers of Class II, III, and IV ceramic capacitors. Since aging is formulation dependent, the aging rate will vary from manufacturer to manufacturer.Question 6 :How does a capacitor manufacturer compensate for aging?Since the capacitance of BaTiO3 based capacitors changes with time, aging poses a unique problem for component manufacturers – that is, ‘what is the capacitance of this capacitor?’Like voltage and frequency test conditions, the industry has long recognized the aging issue and has determined a standard by which all capacitors should be measured : IEC-384-9. Simply stated the capacitance must be within the specified tolerance at 1000 hours age (or TOLH).5The capacitor manufacturer uses the material’s known aging rate and mathematically determines the capacitance tolerance limits for any point in time after de-aging (see figures 3 and 4 below). The components are 100% electrically sorting with respect to its aging rate and TOLH. For example, a +/- 10% tolerance part may be sorted at +13/- 7% if the dielectric material’s aging rate is 3%. By utilizing this technique manufacturers can guarantee all capacitors to be within cap tolerance at 1000 hours based on TOLH.Figure 3 : Example sorting limits for Class Imaterial, K Tolerance(a)(b)Figure 4 : Example sorting limits for Class IImaterial, K ToleranceNOTE : Because aging causes a decrease in capacitance over time, it is possible for the capacitance to be above the upper tolerance limit at times less than 1000 hours from TOLH, and less than the lower tolerance limit at times greater than 1000 hours from TOLH.Question 7 : How should a capacitor user compensate for aging?The capacitor user should expect the Class II, III, and IV capacitors to be within cap tolerance ~ 6 weeks (1000 hrs) from TOLH, the approximate lead time of most components from manufacturer to user. The capacitor user should not expect the Class II, III, or IV component to be within the cap tolerance immediately after solder, glue curing, or any other elevated temperature processes (capacitor will consequently de-aged).In predicting aging/de-aging behavior, in circuit test systems may need to be widened to allow for capacitor aging.References:1EIA-198-D, Page I-12EIA-198-D, Page I-13EIA-198-D, Page I-34Halliday and Resnick, Fundamentals of Physics, 2nd Edition, 1981, Page 4925IEC-384-9 (1988), Appendix AAcknowledgements:1. 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