Why should you not touch electrical appliances with wet hands ? The articles to be plated should be cleaned throughly to remove dust, grease or any deposit on it. Question 1. LED glows showing the flow of current. Place a small compass needle inside it. Question 18. Answer: What colour is the coating? Does lemon juice or vinegar conduct electricity? Why should you not do the experiments on electricity by using electric supply from mains ? Have you ever imagined how electricity is produced and what's the science behind it? Air is an insulator of electricity. Examples are copper, aluminium, etc. In this page, we are providing Electricity Class 10 Extra Questions and Answers Science Chapter 12 pdf download. Add a few drops of dilute sulphuric acid to copper sulphate solution to make it more conducting. The process that you saw in Activity 14.7 is used for purification of copper. (d) Potassium What are electrodes ? Name the gases formed when electric current is passed in water containing a few drops of acid ? An electric eel is a fish that makes its own electricity ,Lightning is spark of electricity in the air and bulb uses electricity to glow. No, pure water doesn’t conduct electricity. Find PowerPoint Presentations and Slides using the power of XPowerPoint.com, find free presentations research about Electricity And Magnetism Class 8 PPT Answer: Electricity was first used in homes for lighting. Paheli had heard that rainwater is as good as distilled water. Question 8. 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Conductors : lemon juice, tap water. A child staying in a coastal region test the drinking water and also the seawater with his tester. Name three liquids, which when tested in the manner shown in figure, may cause the magnetic needle to deflect. Note down the terminal of the battery with which this electrode is connected. (c) Dilute sulphuric acid They can produce a shock of around 500 volts. The sea water contains more salts dissolved in it as compared to the tap water. the movement of electrons. During electroplating, the silver metal from the anode is deposited on the cathode. The bulb may not glow because of the following reasons: What can be the possible reasons for this ? Chemical effects of electric current are used in the working of _____ (a) Electrolytic cells (b) Galvanic cells (c) Electrochemical cells (d) None of these. Can we call the change taking place in the solution a chemical change? He finds that the compass needle deflects more in the case of seawater. Explain your answer. Explain why they do this. Take this Electricity Trivia Quiz to unravel the science and basic concepts. Answer: Chromium is used for electroplating because it has a shiny appearance, does not corrode and is scratch resistant. The free copper, being positively charged, gets drawn to the negative terminal of the battery and gets deposited on it. Answer: Answer: STUDY. Distilled water does not have any salts dissolved in it, but rain water may have some impurities in it. (b) insulator If it is still not working then replace the cells with fresh cells. Explain. Answer: Question 11. Question 12. Why is chromium used for electroplating ? The seawater contains a huge amount of salts in comparison to drinking water, hence the seawater is a better conductor of electricity and it produces a stronger magnetic field in the wire and hence deflects the compass needle more. Or, the bulb is fused? List the possible reasons. Answer: You may also get distilled water from a medical store or a doctor or a nurse). Explain how it can be used for writing. (d) photodiode No, it is highly dangerous to carry out the electrical repairs outdoors during the heavy downpour. View and Download PowerPoint Presentations on Electricity And Magnetism Class 8 PPT. What is the disadvantage of electroplating done in the factories ? When electric current is passed in water hydrogen ions (H+) move towards cathode and get collected over it. Understanding the power of electricity we humans harness is necessary for the wise use and creation of this valuable resource. Spell. Activity 5 (NCERT Textbook, Page 176) Answer: Prepare a list of objects around you that are electroplated. Answer: Answer: Is air an insulator or conductor of electricity ? No, it is not advisable for electrician to carry out electrical repairs during heavy downpour because water is a good conductor of electricity and the person can get shock. Hence, water is avoided in extinguishing electric fires. 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. Iron is a strong metal used for making bridges. This process is known as chemical effects of current. It gets deposited on the [NCERT] It can cause electrocution, as water is a good conductor of electricity. Question 6. Question 13. Answer: The two free ends of wire are connected to the material to be tested. Answer: Now connect one free end of the wire to the terminal of a battery. Thus food, stored in iron cans, is prevented from being spoilt due to iron by electroplating it by tin. Rainwater is pure water which is an insulator but it gets mixed with air pollutants like sulphur dioxide and nitrogen oxides and form acidic solution, which is a good conductor of electricity. For example: All metals including metal wires, copper wires, aluminium foil, etc. These charges can be at rest or moving .Learn how these moving charges constitute current electricity. In order to make electricity useful, we had to find a way to not only generate large amounts of electricity, but to somehow store it. By volume of hydrogen gas is twice the volume of oxygen gas. In metals electric current is conducted by flow of electrons. The compass needle will show deflection with tap water, lemon juice and sodium chloride solution. How would you classify lemon juice or vinegar—a good conductor or a poor conductor? Answer: Question 10. Attach the free ends of the wires to a LED. You would conclude that NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. Explain. A metal is released in the electrolysis of a salt. 14.5. may cause the magnetic needle to deflect. First and second cap with acid and base respectively, conducts electricity whereas third cap having sugar dissolved in distilled water do not conduct electricity. (b) Iron Artificial jewellery is plated with silver or gold. (b) cathode Answer: Gradually, a layer of copper builds up on the plate. 8. Dip the ends of the wire in the given liquid. Can you explain the reason? [NCT 2011] What is the objective of electroplating ? (a) Sea water Wait for 3-4 minutes. Answer: (b), Question 8. Add a teaspoonful of salt or a few drops of lemon juice to water to make it more conducting. Question 6. Question 21. The water used in the water hoses is not pure water and is a good conductor of electricity. Answer: Answer: Answer: 3.00. b) An electric iron of resistance 20Ωtakes a current of … Instead the iron can be galvanised or painted. Solution: Which of the following metal is not extracted by electrolysis? Does pure water conduct electricity? It is concluded that when electric current is passed through the copper sulphate solution, copper sulphate dissociates into copper and sulphate. Collect a few small plastic or rubber caps of discarded bottles and clean them. Bring your tester over this cap and let the ends of the tester dip into lemon juice or vinegar as shown in Fig. This is the Volvo VRN Electric, the company's first electric class-8 truck. Which is the most common application of chemical effect of current ? Question 11. Question 6. Hydroxyl ions (OH )move towards the anode and oxygen is collected on it. A household uses the following electric appliances: (i) Refrigerator of rating 400 W for ten hours each day. The temperature around the electroplating equipment should be optimum. may be the current is so weak that it does not heat the filament of the bulb allowing it to glow. A child staying in a coastal region tests the drinking water and also the seawater with his tester. Question 6. You would conclude that. Question 14. Use plating artificial jewellery with gold. Do you find a coating over it? What is CFL ? What are conductors ? They can produce a shock of around 500 volts. Question 7. Why the iron cans are electroplated with tin ? Answer: What do you find? as a point source of light in laser beam torches. In case of a fire, before the firemen uses the water hoses, they shut off the main electrical supply for the area. Volvo Volvo has been testing the VNR Electric in a range of configurations, like this tractor-trailer. Answer: Answer: How can the magnetic effect be used as a tester ? We will need copper sulphate and two copper plates of size around 10 cm x 4 cm. Question 1. How can you make a tester for testing whether a given material is a conductor or an insulator ? (b) coating (c) electrolysis If the current in the circuit is small, how can we test its presence ? Compact Fluorescent Lamps. In each case observe whether the magnetic needle shows deflection or not. Take out the ends of the tester from the lemon juice, dip them in water and then wipe them dry. Current electricity is when an electrical charge is given a path to move through. A cell is an example of conversion of Thus water which is free of salts are poor conductors while water with salts is a good conductor of electricity. Bridges and automobiles are prevented from rusting by plating them with zinc. (You may obtain distilled water from your school science lab. Example 1• An electric rice cooker operates at 240 V and uses a current of 8 A. Answer: Take about two teaspoonfuls of distilled water in a clean and dry plastic or rubber cap of a bottle. So, the compass needle showed deflection. Sun is the main source of heat energy. What is electroplating? Question 12. Answer: Therefore, we can be electrocuted in case we touch appliances with wet hands. After removing the electrodes from the solution, we find that copper metal gets deposited on the plate at the negative of the battery. The process of depositing a layer of any desired metal on another material by means of electricity is called …………. Answer: What is the Voltage (V) of the rice cooker? Calculate the electricity bill of the household for the month of June if the cost per unit of electric energy is Rs. Answer: Question 10. In 2014, nearly half of electricity used by U.S. manufacturers was for operating machinery.3 1. Which of these materials can … The bulb does not glow because distilled water is an insulator, since it does not have dissolved salts. (a) Aluminium Answer: Answer: Fun facts about the Uses of Electricity. How should LED be connected ? Many powerplants around the globe produce this resource for the massive consumption now experienced but often at great cost to the environment. Electricity is a part of our daily life. Activity 6 (NCERT Textbook, Page 176) Explain why they do this. the concentration of electricity; can be positive or negative. What is electrolysis ? The free copper gets drawn to the plate connected to the negative terminal of the battery and gets deposited on that plate. Electrolysis is the breaking up of a compound from its solution on passing electric current through the electrolyte. But when salt is dissolved in distilled water and again tested, the bulb glows which shows that water containing salts conduct electricity. Question 8. (d) sides of the container Why ? Paheli had heard that rainwater is as good as distilled water. So she collected some rainwater in a clean glass tumbler and tested it using a tester. Water is dissociated into its constituent gases, i.e., hydrogen and oxygen.