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Bohrs Atomic Model

Bohrs Atomic Model Scientist Neils Bohr gave some corrections to Rutherford's atomic model in 1913. This corrected model is called the Bohr's atomic model. The main postulates of this model are - a) The electron moves around the nucleus in a circular motion, about an axis. This circular motion is called an energy level or orbit. They are also known as the shell or permanent orbit or principal energy level. Electrons do not absorb or emit any energy when they revolve these fixed orbits. If we express the permanent orbit as n, then n = 1, 2, 3, 4, etc.  In other words, if n = 1, the principal energy level is K,  when n = 2, L is the principal energy level,  when n = 3, M is the principal energy level,  when n = 4, N is the principal energy level, etc. b) According to Bohr's model, the angular momentum of an electron in an energy level is mvr =  nh / 2𝜋 . Here, m = the mass of the electron (9.11×10 -31  kg) r = the radius of the orbit that the electron follows v = the veloc

How mirror can be identified by observing the values of the magnification?

How mirror can be identified by observing the values of the magnification? If an object is placed within the focal length of a mirror, the image of the object will get magnified in case of a concave mirror, and will get diminished in case of a convex mirror. The value of magnification will be greater than 1 in case of a concave mirror, and less than 1 in case of a convex mirror.

Explain weak nuclear force

Explain weak nuclear force The short-range and small magnitude force that exists between the fundamental particles within the nucleus is called weak nuclear force. Due to this force, the nucleus becomes unstable and beta decay occurs. Most of the radioactive disintegration occurs due to weak nuclear force. The range of this force is less than 10 -16 m.

Define unbalanced force

Define unbalanced force When two or more forces acting on an object produce resultant force, i.e. the object has acceleration; we say that the forces are unbalanced. The forces that produce this unbalanced condition are called unbalanced forces.

My School

Write a paragraph about 'Your School'. My School The name of our school is A.K. High School and College. It is located beside the Dhaka-Chittagong highway. It is one of the best and oldest schools in the district of Dhaka. Our school is a four storied building. It has about thirty-eight rooms. There are sixteen hundred students and thirty-two teachers in our school. Our school library is very rich. There are a lot of books in it. There is a beautiful garden in front of headmaster's room. There are science laboratories in our school. All the teachers are friendly and qualified. They take special care of us and love us dearly. We have a big field in front of our school. The results of our school have all along been satisfactory. We hold annual sports and annual drama every year in our school. We are very proud of our school.

How to make Custard

How to make Custard Quantities needed: 3 eggs, pinch of salt, 1 pint milk, flavouring to taste, 1 tbs sugar. Making process: First, we beat the eggs, salt and sugar enough to mix well. Then, we heat the milk and pour the hot (not boiling) milk on to the eggs and stir well. Next, we need add flavouring to taste. After that, we pour into a greased dish. When using the higher temperature, we place the dish in a baking tin with hot water to come half-way up the sides of the dish. Then, we bake until set. Finally, to test for setting, we slip the blade of a knife into the custard sticking to it, the baking is finished. The custard may not be quite done in the middle, but there will be sufficient heat in it to finish the cooking and taking it out at this stage prevents overcooking and curdling.

How to prepare for the Exam.

How to prepare for the Exam. To prepare for the exam, we should read books according to our class routine. When the teacher teaches in the class, we must listen carefully. If we do not understand any point, we should request him / her to explain it again. At home, we have to read the lesson again and again. We must try to understand what we read. We have to think over the possible questions. Then, we must write answers to those questions. For Arithmetic, we should do the sums ourselves. If necessary, we must take help of others. We shouldn't leave any subject for the exam unprepared.


Tooth-Brushing First, wet the toothbrush and put some toothpaste with fluoride in it on the toothbrush. Then, we brush the teeth vigorously from side to side for quite a while. At the same, time we make sure that the insides of the teeth are thoroughly cleaned.  Finally, we rinse several time the toothpaste foam and the food debris out of the mouth.

How to make a cup of Tea.

How to make a cup of Tea. To make a cup of tea is an easy task. The first step is to put the water-kettle on. When the water boils over, we take the kettle off the boil. The second step is to pour the steaming water into a cup of tea. The third step is to put a tea a bag into the cup. After a while, we take the bag out of the cup. The final step is to put milk and sugar and stir the liquid with a teaspoon. The cup of tea is now ready for drinking.

How to improve our English.

How to improve our English. English is an international language. We should learn it carefully. First, we have to study English regularly right from the beginning of the school year. We must not do cramming. Then, we must try to understand what we read. Therefore, we have to make own notes, get them corrected by our teacher and revise them frequently. Next, we must read our lessons thoroughly and have a fairly good command of the language. After that, we have to read story books written in simple English.  Finally, we must note down the unknown words and look up them in the dictionary.

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