Tesla won and AC is delivered to most homes still today. Answer: Answer: Question 3. of distilled water in a clean and dry beaker. Give some uses of LED. Match. Your tester with two free ends of the wire is ready. They can produce a shock of around 500 volts. Activity 1 (NCERT Textbook, Page 173) Air is an insulator of electricity. So, the deflection of the compass needle is more. Changes of colour of solutions may occur depending on what solution and electrodes are used. Take care that the ends are not more than 1 cm apart but at the same time do not touch each other. No, it is highly dangerous to carry out the electrical repairs outdoors during the heavy downpour. If not, what can we do to make it conducting? Answer: Dec 27, 2020 - Important Questions - Chemical Effects of Electric Current, Science, Class 8 | EduRev Notes is made by best teachers of Class 8. In this activity, if the bulb does not glow, it means that either the connections of the circuit are loose or the bulb is fused or cells are used up. Observe the electrodes carefully. Question 4. Thus food, stored in iron cans, is prevented from being spoilt due to iron by electroplating it by tin. Question 7. Answer: (b) Iron Instead the iron can be galvanised or painted. It is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. Electricity was first used in homes for lighting. Which one of the following is a weak electrolyte ? Question 11. Do you find a deflection in the compass Answer: Explain why they do this. Question 1. Question 4. Solution: It is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. Powdered coal is burnt at high temperature which further turns water into steam. Question 12. Most liquids that conduct electricity are solutions of …………, ………. Answer: Fill in the blanks. (a) Sea water Answer: Jaya sets up a circuit as given below. If the magnetic compass shows deflection glows, it is a conductor, but if it does not deflect, it is an insulator. (d) Nitric acid Method : Question 2. Electrolysis is the breaking up of a compound from its solution on passing electric current through the electrolyte. If they are, then replace the bulb with another bulb. (iv) The liquid may be an insulator, i.e., a poor conductor of electricity. Which properties of chromium make it useful for electroplating on iron ? Question 5. In containers, water evaporates slowly. This process is known as electroplating. When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. What is electrolysis ? Question 5. The writing appears on the paper. Answer: Does lemon juice or vinegar conduct electricity? Take out carbon rods carefully from two discarded cells. What could be the reasons ? What is the basic principle of electric pen ? But when salt is dissolved in distilled water and again tested, the bulb glows which shows that water containing salts conduct electricity. Question 3. Answer: Grade 8 Science - Electricity. Answer: Examples are copper, aluminium, etc. the concentration of electricity; can be positive or negative. Question 6. It can cause electrocution, as water is a good conductor of electricity. What are conductors ? (iv) conducting properties of liquid cannot be compared in this manner. Question 2. Which out of the following does not conduct electricity ? Pour a cupful of water in a glass/ plastic bowl. The decomposition of an electrolyte when electricity is passed through it, is called Question 10. Explain how it can be used for writing. Solution: Insulators : distilled water, milk. Activity 7 (NCERT Textbook, Page 177) (ii) The bulb may be fused. (c) electrolysis Question 1. Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpour? If the ends of the wire of tester are touched for a long time, the cells will be finished very soon. Current electricity is when an electrical charge is given a path to move through. Question 10. (c) chemical energy into electrical energy Name one non-metal which a good conductor of electricity. [NCERT] Answer: To her surprise she found that the compass needle showed deflection. (b), Question 5. Thus, lemon juice, vinegar, tap water, milk, curd and water, and soda are good conductors of electricity while vegetable oil, honey, kerosene oil, and distilled water are poor conductors of electricity or insulators. The free copper, being positively charged, gets drawn to the negative terminal of the battery and gets deposited on it. Add a few drops of lemon juice or dilute hydrochloric acid to distilled water in one cap. How can you make a tester for testing whether a given material is a conductor or an insulator ? 8. Question 10. Answer: Graphite. Do you notice any gas bubbles near the electrodes? Which of these materials can … Pour about two teaspoonfuls of distilled water in each of them. (b) Oxalic acid Take the tray from inside a discarded matchbox. If the tester is put in distilled water, the bulb of the tester does not glow. Now connect one free end of the wire to the terminal of a battery. Connect the copper plates to the terminals of a battery and immerse them in copper sulphate solution (Fig. Protection of the surface of bases metals which corrode for e.g., iron is plated with chromium. Answer: How should LED be connected ? Answer: Have you ever imagined how electricity is produced and what's the science behind it? But the bulb does not glow. The bulb does not glow in the set-up shown in figure. Answer: Electric current can produce magnetic effect also. may be the current is so weak that it does not heat the filament of the bulb allowing it to glow. [NCERT] What are electrodes ? Chemical Effects of Electric Current Class 8 Extra Questions Higher Order Thinking Skills. This is static electricity. However, if the bulb does not glow, it means that the tester is not working. 25% of the city of San Francisco's energy is generated by wind power. (i) The wires in the circuit may be loosely connected. Water is dissociated into its constituent gases, i.e., hydrogen and oxygen. Which of the following metal is not extracted by electrolysis? Join the free ends of the tester together fora moment. This happens because the when current is passed, the K+ ions are attracted to the metal sheet. In case of a fire, before the firemen uses the water hoses, they shut off the main electrical supply for the area. (c) semi-conductor Question 8. Place a small compass needle inside it. Answer: Topics and Sub Topics in Class 8 Science Chapter 14 Chemical Effects of Electric Current: Question 1. Why electric fires are extinguished with either using CO 2 extinguisher or mud but not water? (a) conductor (a) conduction In 2014, nearly half of electricity used by U.S. manufacturers was for operating machinery.3 1. Thus water which is free of salts are poor conductors while water with salts is a good conductor of electricity. Test. 14.1. We prefer not to do electroplating on iron used for bridges because it is very costly. Question 9. Answer: Explain. (a) anode (a) magnetic energy into chemical energy For example: All metals including metal wires, copper wires, aluminium foil, etc. Answer: Connect the negative terminal of battery to the metal sheet. (b), Question 6. Answer: Explain why they do this. Fun facts about the Uses of Electricity. Iron is a strong metal used for making bridges. Our bodies use electricity to communicate including telling our heart to keep beating. LED is Light Emitting Diode. What are insulators ? Question 6. Dinesh is wants to study the chemical effect of current at home. A child staying in a coastal region test the drinking water and also the seawater with his tester. Liquid A is a better conductor than liquid B. The process of depositing a layer of any desired metal on another material by means of electricity is called …………. If it is still not working then replace the cells with fresh cells. Terms in this set (11) Electricity. The bulb in the tester does not glow when current is passed through it. RVers parked in areas where they do not need air conditioning will use much less electricity than RVers who do need it. Activity 2 (NCERT Textbook, Page 773) (6) Electricity is used to pump underground water from tube wells for irrigation in field. Good/Poor Conducting Liquids. Solved Examples for You. These charges can be at rest or moving .Learn how these moving charges constitute current electricity. Name three liquids, which when tested in the manner shown in figure, may cause the magnetic needle to deflect. The bulb may not glow because of the following reasons: [NCT 2011] Our bodies use electricity to communicate including telling our heart to keep beating. (a) anode Sun is the main source of heat energy. Uses of Electroplating. Do you find any difference in any one of them? Test which solutions conduct electricity and which do not. The temperature around the electroplating equipment should be optimum. Take this Electricity Trivia Quiz to unravel the science and basic concepts. Wrap an electric wire a few times around the tray. Paheli had heard that rainwater is as good as distilled water. Flashcards. Why ? Explain why these deposits occur. (d) The process of depositing a layer of any desired metal on another material by means of electricity is called _______ Electricity is a part of our daily life. Materials which allow electric current to flow through them are called conductors. Does the bulb of the tester glow? It is concluded that when electric current is passed through the copper sulphate solution, copper sulphate dissociates into copper and sulphate. Recall the definition of a chemical change that you learnt in Class VII. A change in the electric potential change equals the change in electric potential energy per unit charge. Answer: as a point source of light in laser beam torches. On passing electric current through the conducting solution of lemon juice and water, chemical reaction takes place. Answer: (iii) The cells may be used up. Question 7. So, the fire¬men shut off the electric supply before spraying water to save themselves and other people from electrocution. Chemical Effects of Electric Current Class 8 Science NCERT Intext Activities Solved. Starch to turn blue black of configurations, like this tractor-trailer Volvo Volvo been... 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