Test Papers – National Board Exam (IX-X)
NEET & AIIMS 12th PCB Physics Demo Videos
Hello, students, welcome to the lecture video of the chapter Alternating Current. Current which varies with respect to the time over the range of values. So, in this module we will be solving the problems from a very simple concept, phase shift and time period. So, let’s get started with the first problem.
Two sinusoidal voltages of the same frequency are shown in the diagram. What is the frequency and the phase relationship between the voltage? Frequency in Hertz and phase lead of N over M in radians. So, look at these options and the right answer is b. So, carefully observe the wave forms, we have two wave forms one is M and another N. By taking these two we should find frequency. Finding the frequency is quite easy, as they have mentioned the time period if you carefully observe the wave forms. So, now let us see the solution for this problem. So, phase difference the state of vibration difference. So, when you take a wave form, so at what state it is vibrating that is what we call, its phase. When you compare the same thing with another wave form, the difference what you get, that is what we call phase difference. So, in this case we have wave forms as you see in this case. So, first wave form M, so let me mark the phase for this wave, that is 0 pi by 2 pi 3 pi by 2, 2 pi. And now let us take another wave form that is N. So, it is starting from the phase pi by 2 then what is the difference you can observe. Yes, it is minus pi by 2. It is clear phase lead of N over M is minus pi by 2. Since time period taken to complete one cycle is 0.4 sec. So, now we have got the time period. How to get the frequency then? So, getting the frequency is quite easy out of the time period, frequency is equal to 1 by time period that is going to be 1 divided by 0.4. So, the answer is going to be 2.5 Hertz. So, all you have to observe the starting point between the wave points to know about their phase shift.
So, let’s move on to the next problem. So, in case if the same problem was asked for the case of time difference then the formula is going to be time period divided by 2 pi into phase difference. This is for time difference. When you know the phase difference then only you can go for the time difference. So, let’s move onto the next question.
The instantaneous values of current and voltage in an AC circuit are respectively I is equal to 4 sin omega t and E is equal to 100 cos omega t plus pi by 3. The phase difference between voltage and current is, so, take a look at these options. So, the right answer is c. So, now in this case we have got two waves, so, let us know about the instantaneous values of current and voltage. So, instantaneous current that is i is equal to i0, i0 means peak value sin omega t. Instantaneous voltage v, v is equal to v0, v0 is the peak value of the voltage omega t plus pi. So, what is pi? Yes, it is phase difference between the current and voltage in this case. So, now do we have the same forms even in the problem? So, let us take a look at the given equations, current is given in terms of sin but the voltage are in the case EMF, so is given as the function of cos. So, now let us bring this EMF equation to the sin version. So, as you can do sin of pi by 2 plus omega t plus pi by 3. To convert the cos into sin. When you simplify, the simplified version will be 100 sin omega t plus 5 pi by 6. So, when you carefully observe these two equations. So, by knowing the instantaneous equations, what you find in the place of phase difference. It is 5 pi by 6. So, by just comparing the equations make sure both of them are in the same functions. That means sin, sin, so, in that case what do you get in the place of pi. That is your phase difference.
So, let us move onto the next problem. If the frequency of an alternating current is 50 Hertz then the time taken for the change from zero to positive peak value and positive peak value to negative peak value of current are respectively. So, take a look at these options and the right answer is a. So, we have given the frequency, by using the frequency we should find out the time taken to raise from zero to peak and positive peak to negative peak. So, to understand that let us see the wave form for this. As you have the complete wave here. So, the time taken here to complete one cycle time period. The same time period can be observed in other portion also as you can see. In this case we need to find out for zero to peak value that is, it is going to be from the origin to the peak point then the time period is going to be T divided by 4. So, now the time taken to reach zero to peak value t is equal to T divided by 4, where t is equal to 1 by f that is going to be 1 by 4f when you substitute the frequency the answer is going to be 1 by 200 sec. Is it the end of problem, no? So, you should find out one more time. So, now to understand the concept from the positive to negative peak, take a look at this wave form. In this case we have the time period in this portion and we need to find out the time taken from the positive peak to negative peak. Now, the time taken is going to be T divided by 2. So, now t dash is equal to T divided by 2. T is equal to 1 by f, that is going to 1 by 2, when you substitute the value of frequency, it is going to be 1 by 100 second.
Thank you.
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NEET & AIIMS 12th PCB-Biology -Evolution Demo Videos
Hello, students, in this module we finally begin to study origin and evolution of human being. Students, let’s look at an overall of this process of how did man originate and evolve.
So, let’s begin. The very first attempt was made by Thomas Huxley in his book. What was the name of his book? The name of his book was “Man’s Place in Nature”. He made the first attempt to actually explain the origin of man. He was the one who stated that our closest relatives are apes. Then the second attempt when we speak of evolution, one name that always comes to our mind, Mr. Charles Darwin. So, Charles Darwin back in the year 1871 penned down his idea in another book. What is the name of his book? It’s called as “Descent of Man”. In this book he wrote down about man’s ancestry. Unfortunately, Charles Darwin’s ideas and the ideas of Thomas Huxley were totally misunderstood. But, of course, with the help of fossil record we totally know that be it monkey, be it ape, be it man all of them have arisen from one common ancestor. So, remember that we have not arisen out of ape, he is not our ancestor, he is our relative, because all of these, monkey, ape and man have arisen out of the same common ancestor.
Now, next important name that we have to know Carolus Linnaeus very famous taxonomist, Father of taxonomy, placed man amongst monkeys and apes while he was classifying man. He did one more important job. He gave the first scientific name to man. What is the scientific name of the man, students? Homo sapiens, yes. What does this word Homo sapiens mean? Homo sapiens meaning “a man who is wise”. So, this was the name that was given by Carolus Linnaeus.
Now, students, let’s take a look at the place of humans in the entire animal kingdom. To give you a summary, modern man is always studied under the order Primates and the class Mammalia. We are all mammals. Whenever you see the word Primates, one very important about primates that you should know, they are plantigrade. Plantigrade mean walk on palms and soles.
So, students, let’s now look at the classification of man. We all belong to a class Mammalia, which order, Primates. Order Primates, is further divided into two sub-orders. The first sub-order is known as Prosimii. The second sub-order is known as Anthropoidea. Students, within Prosimii, which kind of animals or which kind of primates do we study. We study 3 typical primates. The first one lemurs, take a look at lemurs. The second one known as lorises, observe the lorises and the third example, students, tarsiers, take a look how does a tarsier appear.
Students, further, under sub-order Anthropoidea, we have 3 divisions. The first division, students, is known as Ceboidea, new world monkey. The second is Cercopithecoidea also known as old world monkey and students the last one is known as Hominoidea, apes and man.
So, we have looked at both the sub-orders, sub-order Prosimii and sub-order Anthropoidea, which we will individually study in the upcoming modules.
So, students, what have we looked at in this module. Students, in this module we have looked at origin and evolution of human being.
Thank you.
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How to Increase Efficiency of Students by Flipped Classrooms?
In order to get maximum benefits through flipped classrooms, one should have an overview of what is it and how it works? Before implementing new things in life, knowing the concept clearly is utmost necessary. Hence, here we have gathered some details on flipped classrooms so that students can have maximum benefits of this concept.
Flipped classrooms is an innovative concept to prepare your chapters or concepts prior to attending the actual class through short video lectures that are created by professionals and experts. You can easily access these videos either online or you can download Robomateplus to get video lectures on different topics. Through these video lectures, you can understand the concept and will be able to implement them while attending the actual class.
Difference Between Traditional Classroom & Flipped Classroom
But the question arises why you need to do that? Well, there are several benefits of these flipped classrooms among which the most prominent one is that you can enhance your efficiency.
How to Increase Efficiency of Students by Flipped Classrooms?
Create Your Own Study Material:- These videos are short and crisp in information hence, it will be helpful for candidates to jot down the important facts and formulas in their own language. As these videos contain only useful and important details, this will help you in identifying the topics through which you can get good marks.
More Time For Practice– In the traditional classroom, one class is consumed by lectures hence, students are left with a small time period to implement the concept but in flipped classroom, students can practice more in classes as they can get the lecture through videos.
Better Time Management Skills– Students can manage their time in a better way through flipped classes as they can learn according to their convenience and availability of time.
More Time For Other Activities- Learning through books is too time consuming as we have to read the same concepts several times to understand it properly. Through video lectures, experts explain the concepts so that you can get a better idea the first time.
Adopting the above-mentioned tips you can enhance your efficiency without cramming the whole syllabus. So, start connecting with experts through video lectures of Robomateplus and ace the exams with good marks.
What is Flipped Classroom Technique? Why Is it Preferred?
Your mind may be stormed with tons of questions related to flipped classes such as: What is it? How does it work? And how can you get benefits through them? Hence, to resolve your queries related to flipped classrooms, we have compiled some answers.
What is Flipped Classroom?
Flipped classrooms are just opposite to the traditional teaching method where students are made familiar with the concepts before attending the class by reading or short video lectures and the time spent in class is utilized in developing strategies such as discussion, problem-solving, or debates.
Why Is It Preferred over Traditional Techniques?
As we have mentioned earlier that through flipped classes you will gain the concept without attending the classrooms. This is the best benefit anyone can ever have. What is your main concern in case you are unable to go school or coaching classes? It is that you will lose the topics and details. Through this method, you do not have to worry about it. Access the video lectures and learn from the convenience of your home. These are time saving techniques for students who save every second to prepare harder for their exam. In addition, students will have below-mentioned benefits through flipped classrooms.
- Students can access these video lectures as per their convenience and can select the best mode of learning that suits their learning pace (e.g. readings, lecture material, interactive multimedia)
- Students can assemble their own resources through the curated content of the flipped class.
- Learning material is available in different formats that is developed on the basis of different styles of learning and multimodal learning (e.g. videos, audio, text, multimedia),
- Chances to interaction and discourse in and out of class through various tools like discussion tools, polling tools, content creation tools
- Well-timed information, reminders and updates through micro-blogging, or announcement tools to each and every student
- Students will be able to receive feedback from students or teachers through quizzes or polls
- The best feature of these classes that you can measure your progress so that you can improve fast.
Considering the benefits of flipped classes, the smartest way to study harder is through short video lectures. So what you are waiting for? Watch the videos and give hard competition to your batch mates.
The Benefits of Flipped Classrooms
The concept of flipped classrooms is being introduced in the current education system in order to enhance the productivity of students. The term may seem new, but in reality, the concept is not. If you remember, in your childhood days, teachers always suggested reading the chapter before coming for the next day lecture.
Considering the same ideology, in the flipped classrooms students have to view the short video lectures, posted by the teachers before attending the actual classes. And the class time is utilized to solve the queries, practice the hardest concept and more.
There are several benefits of the concept, however, we have mentioned five benefits of flip classes.
Benefits of Flipped Classroom
- Better Understanding
In a flipped classroom, students understand the concept more clearly and precisely as they do not have to just read the topic.
In regular classes, students first read the topic and then implement it. There may be the chances that the complete concept won’t complete in one go that creates the discontinuity in study pattern. Hence, lead to low productivity. Going through the concept before the class through short video lectures helps students to view it as many times they can.
- Promotes Student-Centred Learning
Flipped classrooms allow class time be used to master skills through collaborative projects and discussions. With the teacher’s guidance, this method motivates students to learn and teach the concepts from each other. This will help students to own the knowledge they attain which in response enhance confidence. Moreover, students can have one-on-one interaction with the teachers who make you aware of the mistakes in concept application.
- Easily Accessible
The concept of flipped classrooms is based on video lectures which are 24*7 available and easy to access. Sometimes students are forced to skip the classes due to illness, vacations, family issues and more, at that time these video lectures turn lifesavers. Now, one needs not worry about the loss of studies as these online video lectures are just a click away.
- Safe for Students & Easily Accessible for Parents too
The best part of these flipped classes that its benefits are not limited to students only. Parents can now take a breath of relief as they can check out what their children are studying.
- Enhanced Efficiency
Learning through video lectures saves quality time that students can further utilize with family, friends or to practice their hobbies.
So what is stopping you? Start preparation through Flipped Class and make the most out of your schedule.
World Teachers’ Day – Who Was Your Most Inspiring Teacher?
Since 1994, World Teacher’s Day is celebrated on 5th October, every year. The purpose of celebrating this day is to support teachers and to ensure that they will continue to meet the requirements of the future generation. As per UNESCO, World Teachers’ Day signifies a noteworthy token of the understanding, awareness, and appreciation displayed for the crucial contributions of teachers in the field of development and education.
After parents, teachers are the one who shape your personality and teach you all good and bad of life. No matter where you are from, what qualities you have; they never discriminate their students and bestow them with equal knowledge so that students will climb the ladder of success effortlessly. I truly believe that the influence of a good teacher can never be erased. What I am today is because of my teachers who have worked hard to guide me.
I am an introvert by nature. Interacting with fellow students and making friends was never my hobby. I like to observe things first before giving any reaction to them. You can imagine how difficult it was for me to get queries resolved. I remembered clearly, there were only one or two occasions when I actually managed to get up and ask for an answer to my problem. I was scared to face the world. I aspired to give at least one stage performance, but my stage fear never lets me do the same.
While I was struggling hard in 6th standard, a new class teacher was appointed for our section.
At the first meeting, she appeared as any other teacher. With time, her patience, her kindness, her incredible skills to make the things easy to understand and learn, attracted me towards her. I have never enjoyed learning as much I did in her class.
I can still remember her face and name. Her name: Malini Das. She taught us English. Though I was not good at English, her presence and teaching skills got me hooked to her class.
I remember, one of those precious moments, when I learned a lesson of life. She called me to the staff room and asked to enter my name in a group song performance. I was excited inside but I was too conscious about what people thought of me. Will I be able to perform well? And there was the stage fear. The decision was too hard for me to take.
But she urged me to make a decision.
She said,
“Even if you’re the sweetest of all mangoes, there will always be people who prefer strawberries. So, stop trying to fit in. Appreciate yourself. You are the one and only. Learn to stand out. And never forget that you have all the strength to do whatever you want”
Her lines motivated me to give it a shot. With some nervousness and uncertainty, I applied for the performance. That was my first stage performance, I don’t know whether I performed well or not. But my stage fear was gone forever.
According to Joyee Meyer- “Teachers can change a life with just a right mix of chalk and challenges”. This is what exactly happened in my life. My teacher’s presence not only helped me but also inspired me to do better in life.
My thoughts, my personality, the way I talk have been completely changed. I made friends, not for a while, but for a lifetime.
Sometimes, I wonder what if she were not there to guide me. Maybe I wouldn’t have been able to face the world ever or maybe I would have remained confined to my room forever.
At last, I can only say that
“Gurur Brahmaa Gurur Vishnu, Gurur Devo Maheshwarah
Guru Saakshaata Parabrahma, Tasmai Shri Guruve Namah”
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