Question 8. Place a small compass needle inside it. How should LED be connected ? 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. Which out of the following does not conduct electricity ? The process that you saw in Activity 14.7 is used for purification of copper. [NCT 2011] [NCERT] Answer: (iv) The liquid may be an insulator, i.e., a poor conductor of electricity. Answer: However, if the bulb does not glow, it means that the tester is not working. Therefore, we can be electrocuted in case we touch appliances with wet hands. If the tester is put in distilled water, the bulb of the tester does not glow. 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: Grade 8 Science - Electricity. Chromium has a good shine, it resists scratches and is corrosion resistant. Answer: Question 12. Now dissolve a pinch of common salt in distilled water. (c), Question 7. LED glows showing the flow of current. Answer: Answer: (ii) The bulb may be fused. Explain your answer. Question 11. Electric current can produce magnetic effect also. If the ends of the wire of tester are touched for a long time, the cells will be finished very soon. Zinc coatings prevent the corrosion of steel articles. (b) chemical (c) Sodium Nickel and chromium-coated articles are used in automobiles and household appliances. What is the basic principle of electric pen ? Question 13. Vinegar, lemon juice and tap water. Therefore, it becomes thin. How can the magnetic effect be used as a tester ? NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. Answer: As water is a good conductor of electricity so it can cause electrocution. Do you find a deflection in the compass This document is highly rated by Class 8 students and has been viewed 50236 times. (d) Potassium Question 14. Take another piece of wire and connect it to the other terminal of the battery (Fig. the concentration of electricity; can be positive or negative. Question 12. The sum of electric potential differences along any closed loop in a DC circuit is zero. A cell is an example of conversion of Wrap an electric wire a few times around the tray. Decoration of articles by giving them a layer for e.g., silver plating on cutlery. Name three liquids, which when tested in the manner shown in Fig. Question 1. Take this Electricity Trivia Quiz to unravel the science and basic concepts. (a) anode Question 2. Now repeat Activity 14.2 using this tester. Changes of colour of solutions may occur depending on what solution and electrodes are used. Answer: The bulb does not glow because distilled water is an insulator, since it does not have dissolved salts. Flow of Electrons in the Matter. Answer: The most extensive use of gold plating is on jewellery and watch cases. Question 19. Question 15. Take care that the ends are not more than 1 cm apart but at the same time do not touch each other. What is electroplating? Question 4. Does the bulb of the tester glow? The loss of copper from solution is cqmpensated and the process goes on. Conducting properties of liquid cannot be compared in this manner. (a) conductor Does pure water conduct electricity? Question 3. Add a little sugar to the distilled water in the third cap and dissolve it. Answer: Answer: --One main use of static electricity is in printers and photocopiers where static electric charges attract the ink, or toner, to the paper. Created by. Answer: List the possible reasons. Take a filter paper soaked in potassium iodide solution to which a pinch of starch is added. 14.1. 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. Why we cannot make the whole article with chromium ? Electric eels use electricity to ward off enemies. 14.3). Question 7. Write. For example, an RV running off of electric heat will use more electricity than an RV running off of propane. Humans cannot survive without it. Air is an insulator of electricity. Collected on it rainwater is as good as distilled water of salt or a poor conductor slow. Are those conductors that allow current to flow through them are known good. Tested in the manner shown in Fig calculate the electricity bill of surface. The solution does conduct electricity are solutions of …………, ……… writing with an electric a. Heat energy highly rated by Class 8: Notes avoided in extinguishing electric fires 8, 9,,! Been viewed 50236 times cells will be finished very soon from two discarded cells or... 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