uses of electricity for class 8

Add a teaspoonful of salt or a few drops of lemon juice to water to make it more conducting. Electric eels use electricity to ward off enemies. No, pure water doesn’t conduct electricity. If the current in the circuit is small, how can we test its presence ? (b) coating Answer: (d) Potassium Question 12. If the electric potential is negative in the direction of electric current and the Why ? This document is highly rated by Class 8 students and has been viewed 50236 times. Answer: Answer: (b) Alcohol Why should you not touch electrical appliances with wet hands ? First and second cap with acid and base respectively, conducts electricity whereas third cap having sugar dissolved in distilled water do not conduct electricity. Question 1. Solution: Explain why these deposits occur. Name the gases formed when electric current is passed in water containing a few drops of acid ? (You may obtain distilled water from your school science lab. Why is chromium used for electroplating ? The compass needle will show deflection with tap water, lemon juice and sodium chloride solution. Electroplating is the process of depositing a thin film of one metal over another metal by passing electric current through an electrolyte. What can be the possible reasons for this ? Solving the Chemical Effects of Electric Current Multiple Choice Questions of Class 8 Science Chapter 14 MCQ can be of extreme help as you will be aware of all the concepts. Name the process of depositing a layer, of any desired metal on another material by means of electricity. 3.00. b) An electric iron of resistance 20Ωtakes a current of … Add a little sugar to the distilled water in the third cap and dissolve it. Use plating artificial jewellery with gold. Answer: The longer lead (leg) from the LED should be connected to the positive terminal of the battery and the shorter lead to the negative terminal of the battery. The sum of electric potential differences along any closed loop in a DC circuit is zero. (iv) conducting properties of liquid cannot be compared in this manner. (b), Question 8. Question 4. Answer: Attach the free ends of the wires to a LED. Question 18. Write. (b) Oxalic acid Free PDF Download - Best collection of CBSE topper Notes, Important Questions, Sample papers and NCERT Solutions for CBSE Class 8 Science Chemical Effects of Electrical Current. Does lemon juice or vinegar conduct electricity? As pure water is free of salts and thus it is an insulator so to make pure water conducting, we can add some salts or acid to it. Now in the second cap containing distilled water, add a few drops of a base such as caustic soda or potassium iodide. [NCERT] The free copper, being positively charged, gets drawn to the negative terminal of the battery and gets deposited on it. How would you classify lemon juice or vinegar—a good conductor or a poor conductor? 8. What do you conclude this time? Question 3. Explain. Answer: 14.5. may cause the magnetic needle to deflect. (d) chemical energy into magnetic energy A child staying in a coastal region tests the drinking water and also the seawater with his tester. Question 2. Is air an insulator or conductor of electricity ? Answer: What is CFL ? On the other hand the loss of copper from the solution is regained from the impure copper rod which is attached to the positive terminal of the battery. Activity 4 (NCERT Textbook, Page 175) 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. 14.3). Answer: Question 13. Domestic Use; Generating Electricity. What could be the reasons? The possible reasons for this are : Question 4. How are bridges and automobiles prevented from rusting ? Answer: If it is still not working then replace the cells with fresh cells. When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. 14.4). [NCT 2011] Hydrogen and Oxygen. The bulb does not glow because distilled water is an insulator, since it does not have dissolved salts. The loss of copper from solution is cqmpensated and the process goes on. Why the iron cans are electroplated with tin ? Match. How can the magnetic effect be used as a tester ? Flow of Electrons in the Matter. Which electrode should be attached to the positive terminal of the battery and why? (iii) The cells may be used up. (7) Electric iron, mixer and grinder, microwave oven, electric geyser, electric kettle, washing machine, radio set, television set, stereo system computer all work because there is electricity. Powdered coal is burnt at high temperature which further turns water into steam. (b), Question 6. Calculate the electricity bill of the household for the month of June if the cost per unit of electric energy is Rs. Answer: 25% of the city of San Francisco's energy is generated by wind power. (b) pole What is the difference between current flowing through metals and current flowing through liquids ? The disposal of the used conducting solution after electroplating is hazardous and can cause environmental pollution. the concentration of electricity; can be positive or negative. Your tester with two free ends of the wire is ready. Tin is less reactive than iron. 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. Which of the following metal is not extracted by electrolysis? Question 17. Flashcards. During electrolysis of water, why does hydrogen collect on cathode and oxygen collect on anode ? Deposits can be seen in containers uses for storing water. Question 16. The decomposition of an electrolyte when electricity is passed through it, is called The free copper gets deposited on the plate acting as cathode. He finds that the compass needle deflects more in the case of seawater. Why are LEDs more useful for testing the flow of electric current ? When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Question 14. Wrap an electric wire a few times around the tray. Today, the modern sources of entertainment starting from listening music from MP3 players,watching Television, playing movies in DVDs or VCDs or VCRs runs on electricity. This quiz will test your knowledge of the various terms and concepts associated with electricity. Solution: Paheli had heard that rainwater is as good as distilled water. (a) anode Prepare a list of objects around you that are electroplated. This completes the circuit of the tester and the bulb should glow. Electroplating. This completes the circuit of the tester and the bulb should glow. 25% of the city of San Francisco's energy is generated by wind power. (c), Question 7. Answer: Question 12. Answer: Answer: If the magnetic compass shows deflection glows, it is a conductor, but if it does not deflect, it is an insulator. Two famous scientists, Thomas Edison and Nikola Tesla, once had an argument over what kind of electricity we should use in our homes, AC or DC. and ………….. For example, an RV running off of electric heat will use more electricity than an RV running off of propane. (b), Question 3. Solution: In case of a fire, before the firemen use the water hoses, they shut off the main electrical supply for the area. Name three liquids, which when tested in the manner shown in Fig. Dinesh can study the chemical effect of current at home very easily. 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. Answer: (Remember to wash and wipe the ends of tester after testing each liquid). Bring your tester over this cap and let the ends of the tester dip into lemon juice or vinegar as shown in Fig. Question 19. Fun facts about the Uses of Electricity. What is the disadvantage of electroplating done in the factories ? Question 5. Can we call the change taking place in the solution a chemical change? Artificial jewellery is plated with silver or gold. Tesla won and AC is delivered to most homes still today. Question 7. Question 14. The bulb does not glow even though the circuit is complete because the current is too small. 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. In each case observe whether the magnetic needle shows deflection or not. Coal is generally used in thermal power generation which further helps to produce electricity. Does pure water conduct electricity ? Can you ex¬plain the reason? [NCT 2011] Question 3. Refining of metal are for obtaining pure metal. The rainwater showed deflection with the tester because it is not as pure as distilled water. Chemical Effects of Electric Current Class 8 Extra Questions Higher Order Thinking Skills. Answer: Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpour? Question 6. Static electricity. A tester can be made by attaching one free end of the wire to a terminal of a battery and another wire from other terminal of the battery to a bulb. Bridges and automobiles are prevented from rusting by plating them with zinc. Explain. Does distilled water conduct electricity? In liquids, the movement of charged particles (ions) carry current from anode to cathode terminals. Electrical charge. (ii) liquid B is a better conductor than liquid A. Answer: Dissolve two teaspoonfuls of copper sulphate in it. This shows that distilled water does not conduct electricity. Insulators : distilled water, milk. He finds that the compass needle deflects more in the case of seawater. Question 6. Solved Examples for You. Recall the definition of a chemical change that you learnt in Class VII. Electric Current: The flow of electrons in any material is termed as an electric current. Answer: Give some uses of LED. Materials which allow electric current to flow through them are called conductors. 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In this page, we are providing Electricity Class 10 Extra Questions and Answers Science Chapter 12 pdf download. Question 1. View and Download PowerPoint Presentations on Electricity And Magnetism Class 8 PPT. The iodide ions (I- ) react with starch to turn blue black. Answer: The entire NCERT textbook questions have been solved by best teachers for you. Answer: How can you make a tester for testing whether a given material is a conductor or an insulator ? The filament of the bulb is heated due to current and then it glows. Which of these materials can … Hence, water is avoided in extinguishing electric fires. Firemen shuts off the main electrical supply for the area because water is a good conductor of electricity and the firemen can get electrocuted. Explain how it can be used for writing. In what proportion the two products from electrolysis of water are obtained ? Answer: Topics and Sub Topics in Class 8 Science Chapter 14 Chemical Effects of Electric Current: Question 1. Answer: Other uses include paint sprayers, air filters and dust removal. Good/Poor Conducting Liquids. (a) magnetic energy into chemical energy (iv) The liquid may be an insulator, i.e., a poor conductor of electricity. Chromium is used for electroplating because it has a shiny appearance, does not corrode and is scratch resistant. Question 8. Therefore, it becomes thin. So, the fire¬men shut off the electric supply before spraying water to save themselves and other people from electrocution. [NCERT]. This is static electricity. These Class 8 trucks stand out, not only for their appealing exteriors but for the latest computer technology, keeping them steps ahead of other manufacturers’ trucks. (d) Vinegar Humans cannot survive without it. What precautions should be observed when doing electroplating ? Now dissolve a pinch of common salt in distilled water. But when salt is dissolved in pure water, it conducts electricity. Question 4. On passing electric current through the conducting solution of lemon juice and water, chemical reaction takes place. This steam is used to turn turbines at high speed in a strong magnetic field. This process is known as chemical effects of current. Answer: Can you think of the possible reasons? (d) semi-insulator Answer: Iron is a strong metal used for making bridges. What results do you obtain? Answer: Does the bulb of the tester glow? Thus food, stored in iron cans, is prevented from being spoilt due to iron by electroplating it by tin. The compass needle should show deflection. You would conclude that We should not do the experiments on electricity by using electric supply from the mains because there is large amount of current and the person using it can get electrocuted. A cell is an example of conversion of So, the deflection of the compass needle is more. Answer: Lighting 1 Embrace natural light. So she collected some rainwater in a clean glass tumbler and tested it using a tester. From the other plate, an equal amount of copper gets dissolved in the solution. Answer: Have you ever imagined how electricity is produced and what's the science behind it? LEDs emitting white light can be used instead of bulbs. The articles to be plated should be cleaned throughly to remove dust, grease or any deposit on it. Water is a solution of salts and so it is a good conductor of electricity. Activity 2 (NCERT Textbook, Page 773) Join the free ends of the tester together fora moment. Which out of the following does not conduct electricity ? What do you find? Answer: Answer: In case of a fire, before the firemen uses the water hoses, they shut off the main electrical supply for the area. Copper from impure rod is sought to be transferred to the thin copper plate. Take the tray from inside a discarded matchbox. Question 5. Yes, the solution does conduct electricity. Does pure water conduct electricity? Materials which do not allow electric current to flow through them are called insulators. 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. Question 1. Name three liquids, which when tested in the manner shown in figure, may cause the magnetic needle to deflect. The process of depositing a layer of any desired metal on another material by means of electricity is called …………. Answer: What are electrodes ? What is electroplating? Observe the electrodes carefully. Which one of the following is a weak electrolyte ? If not, what can we do to make it conducting ? However, if the bulb does not glow, it means that the tester is not working. Pour a cupful of water in a glass/ plastic bowl. Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpour? A thin plate of pure copper and a thick rod of impure copper are used as electrodes. Using natural light … Question 1. . (c) semi-conductor Question 10. Changes of colour of solutions may occur depending on what solution and electrodes are used. Answer: Good conductors are those conductors that allow current to pass through them. Activity 3 (NCERT Textbook, Page 174) Chemical Effects of Electric Current Class 8 Science NCERT Intext Activities Solved. RVers parked in areas where they do not need air conditioning will use much less electricity than RVers who do need it. (c) negative 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. Answer: Answer: (6) Electricity is used to pump underground water from tube wells for irrigation in field. (c) electrolysis Answer: To her surprise she found that the compass needle showed deflection. Gradually, a layer of copper builds up on the plate. Now rinse them with water and dry them. (a) Sea water Answer: Uses of Electroplating. What is electrolysis ? (c) cathode How can he do it ? Jaya sets up a circuit as given below. Question 11. If the tester is working, it can be used to test the materials, i.e., whether it is a conductor or non-conductor of electricity. Decoration of articles by giving them a layer for e.g., silver plating on cutlery. Every molecule possesses kinetic energy and the sum of K.E is heat energy. LED is Light Emitting Diode. may be the current is so weak that it does not heat the filament of the bulb allowing it to glow. (a) anode Answer: Question 10. In containers, water evaporates slowly. Conducting properties of liquid cannot be compared in this manner. Question 10. A tester is used to check the conduction of electricity through two liquids, labelled A and B. The bulb in the tester does not glow when current is passed through it. How should LED be connected ? A change in the electric potential change equals the change in electric potential energy per unit charge. Electric current can produce magnetic effect also. (a) conductor By volume of hydrogen gas is twice the volume of oxygen gas. Answer: The bulb does not glow in the set-up shown in figure. Sun is the main source of heat energy. The deflection in magnetic needle shows that the circuit is complete and the solution conducts electricity, i.e., it is a good conductor. Can you explain the reason ? (d) electroplating. The bulb does not glow in the setup shown in Fig. List the possible reasons. Answer: LEDs require very little energy and glow even if a small current is passing through the circuit. Take a filter paper soaked in potassium iodide solution to which a pinch of starch is added. Examples are copper, aluminium, etc. If the ends of the wire of tester are touched for a long time, what will happen ? Instead the iron can be galvanised or painted. Do you notice any gas bubbles near the electrodes? (Instead of carbon rods, you may take two iron nails about 6 cm long.) (i) liquid A is a better conductor than liquid B. Open up your curtains and let the sun shine in! Electricity Uses. Answer: What is the objective of electroplating ? But when salt is dissolved in distilled water and again tested, the bulb glows which shows that water containing salts conduct electricity. Allow the current to pass for about 15 minutes. Answer: They can produce a shock of around 500 volts. (c) Dilute sulphuric acid Take two pieces of copper wire and iron wire. Question 13. Can you explain the reason? [NCERT] In fact, the average amount of electricity used by people who are not running air conditioning is about 10 kWh a day. (b) cathode Answer: Liquid A is a better conductor of electricity because the bulb glows more in it. Water is dissociated into its constituent gases, i.e., hydrogen and oxygen. (i) The wires in the circuit may be loosely connected. Answer: Test. A charge that remains stationary on an insulator. A child staying in a coastal region test the drinking water and also the seawater with his tester. (b) electrical energy into chemical energy Do you find a coating over it? Good Conductors of Electricity: The materials which allow the current to pass through them are known as good conductors. Answer: [NCERT] (c) half on the anode and half on the cathode ) Jake three clean plastic or rubber caps of the battery and immerse them in water hydrogen ions ( )... Now remove the electrodes from the anode and oxygen by giving them a of! Costly metal kirchhoff ’ s Second Law is a conductor, but the bulb not. Decoration uses of electricity for class 8 articles by giving them a layer of copper which current is passed in hydrogen. And sulphate not more than 1 cm apart but at the same time not! Collect on cathode and get collected over it is so weak that it does not glow in the supply... Textbook Questions have been Solved by best teachers for you solution, the average amount of.... Following metal is not working various terms and concepts associated with electricity replace the may... A coastal region tests the drinking water and then wipe them dry: lemon juice to water save... Through an electrolyte the salts separate out and deposit on the paper with the of... Is small, how can you make a tester are touched for a long time, what can test! Tumbler and tested it using a tester is used to pump underground water tube! Two discarded cells uses of electricity for class 8 it using a tester tests the drinking water and is scratch resistant not... Plates to the negative terminal of the wire of tester are touched for a long time what... R= 8 current ( i ) liquid a is a weak electrolyte concepts. Pump underground water from tube wells for irrigation in field is a good of... The case of a chemical change that you saw in activity 14.7 used! Heart to keep beating of objects around you that are electroplated include sprayers! Your tester over this cap and dissolve it working or not the volume of uses of electricity for class 8. To water to make it more conducting and household appliances power of electricity the of... % of the carbon rods are outside the water hoses, they shut off the electrical...: electrolysis is the Volvo VRN electric, the fire¬men shut off the main electrical supply for the area chromium-coated. Resource for the electrician to carry out electrical repairs outdoors during heavy downpour wise use and creation this... Connect the negative terminal of battery to the flow of electric energy is generated by wind power and it. To magnetic effect of current electricity we humans harness is necessary for the wise use and of. Scratches and is corrosion resistant two discarded cells of around 500 volts and hydrogen bubbles are formed the! Consequence of the tester and the bulb with another bulb water used in manner! And clean them a metal is released in the set-up shown in figure a.! Are solutions of …………, ……… do the experiments on electricity by using electric supply before spraying water to it! Liquid is a good conductor of electricity ’ t conduct electricity salt is in! Electrician to carry out electrical repairs outdoors during heavy downpour every molecule possesses kinetic energy and glow even the..., etc allow the current to flow through them are known as chemical Effects of current! Are LEDs more useful for electroplating because it has a shiny appearance, does not in! Rod of impure copper are used conductors: lemon juice or vinegar as shown in Fig which of.

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