Very Short Answer Type Questions (1 mark each)
Q. 1. Mention the angle between a current carrying conductor and magnetic field for which the force experienced by this current carrying conductor placed in magnetic field is largest. Ans. The angle between current carrying conductor and magnetic field is 90 deg. Q. 2. Mention the advantage of A.C. over D.C. for long distance transmission. Ans. A.C. can be easily transmitted over long distances without much loss of energy. Q. 3. In domestic electric circuit, with which wire do we connect a fuse ? Ans. Live wire. Q. 4. List any one point of difference between A.C. and D.C. Ans. Direct current always flows in one direction and alternating current reverses its direction periodically. Q. 5. Name the physical quantities which are indicated by the direction of thumb and forefinger in the Fleming s right hand rule ? Ans. Direction of motion of the conductor and direction of field. Q. 6. Name the device used to prevent damage to the electrical appliances and the domestic circuit due to overloading. Ans. Electric fuse. Q. 7. Name the type of current : (a) Used in household supply. (b) Given by a cell. Ans. (a) Alternating current 1/2 (b) Direct current. Q. 8. State the value of potential difference between the live wire and the neutral wire in our country. Ans. 220 V Q. 9. State the effect on the strength of magnetic field produced at a point near a straight conductor if the electric current flowing through it increases. Ans. The strength of the magnetic field increases. Q. 10. State a difference between the wires used in the element of an electric heater and in a fuse. Ans. The melting point of the wire used in heater elements is high while a fuse wire has low melting point. Q. 11. State the observation made by Oersted on the basis of his experiment with current carrying conductors. Ans. Every current carrying conductor has a magnetic field around it. Q. 12. Suggest one way of discriminating a wire carrying current from a wire carrying no current. Ans. Bring a magnetic needle near the wire, a current carrying wire will produce a deflection in the needle whereas a wire without current will not. Q. 13. List two sources of magnetic fields. Magnet, moving charges, electric current. (any two) State the effect of a magnetic field on the path of a moving charged particle Ans: It can deflect the path of the charged particle. Q.14. An alternating current has a frequency of 50 Hz. How many times does it change its direction in one second ? Ans: 100 times. Q.15. State the use of earth wire in domestic electric circuit. Ans: To ensure that any leakage of current to the metallic body of the appliance does not give shock to the user. Q.16. State the conclusions that can be drawn from the observation that a current carrying wire deflects a magnetic needle placed near it. Ans: A magnetic field exists around it. Read full papers
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class12 physics 2016-17 CBSE Study material Download File class12 Chemistry 2016-17 CBSE Study material Download File class12 Maths 2016-17 CBSE Study material Download File You may also like : Science stream class 12 Study Material old CBSE Class X Exam Results 2016 To be announced on May 28, 2016
CBSE Class 10 results 2016: A total of 13,73,853 students have appeared for Class 10 exam The Class X results for all the CBSE regions will be declared on Saturday, May 28 at 2 pm. This year also, the CBSE will post the results on net with the technical support of National Informatics Centre (NIC). The students can access their results through following websites: www.results.nic.in or http://www.cbseresults.nic.in or http://www.cbse.nic.in. P. 27 Oral Questions For Formative Assessment
1. No. All microbes are not harmful. some are useful as well. 2. a. Algae b. Viruses 3. They cannot reproduce on their own but are to reproduce by using the energy of the host cells. 4. Algae, in the sense that they are capable of producing their own food. 5. In a pond, P. 32 Oral Questions For Formative Assessment 1. That substance is the carbon dioxide_ Carbon dioxide, a gas. as it escapes it causes dough to rise. 2. This is ensured by using dead or weakened microbes. The process is called vaccination. 3. Certain bacteria and protozoa living in animals like cows, goats and sheep help these animals in digesting grass and plants by breaking down cellulose. 4. No. Pasteurization of milk consists of heating milk to a high temperature of around 70 '2C for about half a minute and then cooling it quickly, P. 33 For Formative and Summative Assessment A.1.c 2.d 3.a 4.a 5.d. 6. b 7.c 8.a 9.d 10.c B. 1. Microbiology 2. False 3. False 4. Cyst 5. Cocci 6. False 7. False 8. Desirable 9. Antibiotics 10. Bacterium 11. dengue 12, virus 13. True 14. Pasteurization 15. True C. 1. An organism that is so small that it can only be seen through a microscope, is called a microorganism 2. Bacteria, Algae, Protozoa, Fungi and Viruses. Among these, Bacteria and Protozoa are unicellular organisms.. 3. a. Cocci b. Bacilli c. Spirilla 4. Simple plant like organisms that have cell walls and chlorophyll within the cells are classified under algae. They make their own food by photosynthesis. Some examples of algae are spirogyra, chlamydomonas and focus. 5. Viruses cannot reproduce by themselves. However, when a virus enters the living cell of an organism, it Is able to reproduce. It uses the energy of the host cells for this purpose. After the formation of thousands of viruses, the host cell often dies. 6. Algae are used as food because they are a rich source of vitamins A, C, D and E, 7. Cooling helps in food preservation, It stops microbes growing and reproducing, and hence preserves food. 8. Microorganisms growing art food sometimes produce toxic substances. These make the food poisonous. Consuming such food can cause a serious illness called food poisoning. 9. Pasteurization of milk consists of heating it to a high temperature of 70 "C for about half a minute and then cooling it quickly. This kills most of the bacteria without affecting the flavor, C. 1. Mosquitoes act as carriers of germs. For example, when houseflies sit on dirt, germs stick to their bodies. When they sit on food, they transfer the germs to the food. 2. Most micro-organisms are hardy and can be found even in places where no other life forms can exist. They are so hardy because they form a hard outer covering called a cyst around themselves, specifically during unfavorable conditions_ They survive by remaining inactive within the cyst till the conditions are favourable again. 3. Yeast is used to make bread soft and fluffy. The yeast uses sugar for food. the process of breaking down sugar. alcohol is formed and carbon dioxide is given off. This process is known as fermentation. The bubbles of carbon dioxide given off cause the dough to rise. This dough can be used to make bread. When this dough is baked, more bubbles of gas are formed due to heat. As the gas escapes, the bread rises and becomes soft and fluffy. The heat during the baking process also evaporates the alcohol. 4. The process of breaking down of sugar by yeast into alcohol and carbon dioxide is known as fermentation. The process of fermentation of sugar by yeast is used in the manufacture of alcohol and alcoholic drink such as beer and wine. Wine is prepared by fermentation of sugar in grapes and beer by fermentation of sugar in germinating barley. 5. Viruses cause diseases by invading hosts body. They can enter in the following ways:
7. Salt prevents food spoilage by checking the growth of bacteria_ Safi forces microorganisms wafer by a process called osmosis. 8. Dehydration of food consists of removing water from it. This stops microorganisms from growing as they cannot grow without water, Cereals, pulses, spices and dry fruits are preserved by this method. 9. Microorganisms such as bacteria, fungi and protozoa. act as decomposers. By decomposing the tissues of dead organisms they break down plant and animal tissues into Simple substances and sent back nutrients to the soil_ Without this piles of dead organisms would cover the earth. Some bacteria decompose sewage and other wastes in water. This is nature's method of keeping the environment free from pollution. E. 1. Viruses are considered to be on the borderline of living and non-living due to the following reasons: (i) They do riot have cell body and other structures like other microbes. ii) They cannot reproduce by themselves. (iii) They are able to reproduce only when they enter in a host cell. Since reproduction is a very important characteristic of life, viruses are regarded as a risk extreme living and non-living. 2. Useful activities of bacteria:
1. (a) Because the higher temperature in summers favours the growth of Lactobacillus bacteria. (b) Because the higher temperature in summers favours the growth of Lactobacillus bacteria, 2. Nitrogen is used to inhibit growth of bacteria, which keeps the chips fresh for a longer time. 3. To prevent contamination of disease-causing microbes of our rood we should always wash our hands before handling food and after going to toilet. 4. The life span of bacteria is very short and they reproduce very quickly. Because of this thousands of generations pass within a few years. Therefore evolution, such as becoming resistant to antibiotics, occurs in bacteria within our own lifetime. Living science class8 microorganism solution pdf download Download File Living science class 8:Microorganism solution extra score Download |
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