{"id":16021,"date":"2023-12-07T10:20:30","date_gmt":"2023-12-07T04:50:30","guid":{"rendered":"https:\/\/www.aplustopper.com\/?p=16021"},"modified":"2023-12-08T17:50:23","modified_gmt":"2023-12-08T12:20:23","slug":"selina-icse-solutions-class-10-physics-electrical-power-household-circuits","status":"publish","type":"post","link":"https:\/\/www.aplustopper.com\/selina-icse-solutions-class-10-physics-electrical-power-household-circuits\/","title":{"rendered":"Selina Concise Physics Class 10 ICSE Solutions Electrical Power and Household Circuits"},"content":{"rendered":"
APlusTopper.com provides step by step solutions for Selina Concise ICSE Solutions for Class 10 Physics Chapter 9 Electrical Power and Household Circuits. You can download the Selina Concise Physics ICSE Solutions for Class 10 with Free PDF download option. Selina Publishers Concise Physics for Class 10 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.<\/p>\n
Download Formulae Handbook For ICSE Class 9 and 10<\/a><\/p>\n ICSE Solutions<\/a>Selina ICSE Solutions<\/a><\/p>\n Selina ICSE Solutions for Class 10 Physics Chapter 9 Electrical Power and Household Circuits<\/strong><\/p>\n Solution 1.<\/strong><\/span><\/p>\n The electric power is generated at 11 KV, 50Hz at the power generating station.<\/p>\n Solution 2.<\/strong><\/span><\/p>\n Solution 3.<\/strong><\/span><\/p>\n Electric power from the generating station is transmitted at 11 kV because voltage higher than this causes insulation difficulties, while the voltage lower than this involves high current and loss of energy in form of heat (I2<\/sup>Rt).<\/p>\n Solution 4.<\/strong><\/span><\/p>\n At 220 V of voltage and 50 Hz of frequency, the a.c. is supplied to our houses.<\/p>\n Solution 5.<\/strong><\/span><\/p>\n (a) Step-up transformer Solution 6.<\/strong><\/span><\/p>\n (a) The three connecting wires used in a household circuit are:<\/p>\n (b) Among them neutral and earth wires are at the same potential. Solution 7.<\/strong><\/span><\/p>\n Before the electric line is connected to the meter in a house, a fuse of rating (\u2248 50 A) is connected in the live wire at the pole or just before the meter. This fuse is called the pole fuse. Solution 8.<\/strong><\/span><\/p>\n Solution 9.<\/strong><\/span><\/p>\n The electric meter in a house measures the electrical energy consumed in kWh. Solution 10.<\/strong><\/span><\/p>\n The main fuse in a house circuit is connected on the distribution board, in live wire before the main switch.<\/p>\n Solution 12.<\/strong><\/span><\/p>\n Solution 13.<\/strong><\/span> Solution 14.<\/strong><\/span><\/p>\n All the electrical appliances in a building should be connected in parallel at the mains, each with a separate switch and a separate fuse connected in the live wire so that the switching on or off in a room has no effect on other lamps in the same building.<\/p>\n Solution 16.<\/strong><\/span><\/p>\n In set A, the bulbs are connected in series. Thus, when the fuse of one bulb blows off, the circuit gets broken and current does not flow through the other bulbs also. Solution 1 (MCQ).<\/strong><\/span><\/p>\n The main fuse is connected in live wire. Solution 2 (MCQ).<\/strong><\/span><\/p>\n Electrical appliances in a house are connected in parallel. Solution 3 (MCQ).<\/strong><\/span><\/p>\n Energy Exercise 9(B)<\/strong><\/span><\/p>\n Solution 1.<\/strong><\/span><\/p>\n An electric fuse is a safety device, which is used to limit the current in an electric circuit. The use of fuse safeguards the circuit and appliances connected in that circuit from being damaged. Solution 2.<\/strong><\/span><\/p>\n ‘Fuse’ is used to protect electric circuits from overloading and short circuiting. It works on heating effect of current.<\/p>\n Solution 3.<\/strong><\/span><\/p>\n (a) A fuse is a short piece of wire of material of high resistance and low melting point. Solution 4.<\/strong><\/span><\/p>\n The fuse wire is fitted in a porcelain casing because porcelain is an insulator of electricity.<\/p>\n Solution 5.<\/strong><\/span> Solution 6.<\/strong><\/span> Solution 7.<\/strong><\/span><\/p>\n The fuse wire is always connected in the live wire of the circuit because if the fuse is put in the neutral wire, then due to excessive flow of current when the fuse burns, current stops flowing in the circuit, but the appliance remains connected to the high potential point of the supply through the live wire. Now if a person touches the appliance, he may get a shock as the person will come in contact with the live wire through the appliance.<\/p>\n Solution 8.<\/strong><\/span><\/p>\n The 20 A fuse wire will be thicker so that its resistance be low.<\/p>\n Solution 9.<\/strong><\/span><\/p>\n It means that the line to which this fuse is connected has a current carrying capacity of 5 A.<\/p>\n Solution 10.<\/strong><\/span><\/p>\n The safe limit of current which can flow through the electrical appliance is I = P\/V = 5000\/200 = 25 A; which is greater than 8 A. So, such fuse cannot be used.<\/p>\n Solution 11.<\/strong><\/span> Solution 12.<\/strong><\/span><\/p>\n A switch is an on-off device for current in a circuit (or in an appliance). The switch should always be connected in the live wire so that the appliance could be connected to the high potential point through the live wire. In this position the circuit is complete as the neutral wire provides the return path for the current. When the appliance does not work i.e., in off position of the switch, the circuit is incomplete and no current reaches the appliance. Solution 13.<\/strong><\/span><\/p>\n A switch should not be touched with wet hands. If water reaches the live wire, it forms a conducting layer between the hand and the live wire of the switch through which the current passes to the hand and the person may get a fatal shock.<\/p>\n Solution 14.<\/strong><\/span><\/p>\n Let a switch S1<\/sub>\u00a0be fitted at the bottom and a switch S2<\/sub>\u00a0at the top of the staircase. Fig. (a) shows the off position of the bulb. Similarly, on operating the switch S2<\/sub>, the connection ‘bc’ changes to ‘ba’, which again completes the circuit [Fig. (c)]. Solution 15.<\/strong><\/span><\/p>\n All electrical appliances are provided with a cable having a plug at one end to connect the appliance to the electric supply. Solution 16.<\/strong><\/span><\/p>\n The three pins in the plug are labelled as Solution 17.<\/strong><\/span> Solution 18.<\/strong><\/span><\/p>\n (a) 1 \u2013 Earth, 2 \u2013 Neutral, 3 – Live Solution 19.<\/strong><\/span><\/p>\n Local earthing is made near kWh meter. In this process a 2 – 3 metre deep hole is dug in the ground. A copper rod placed inside a hollow insulating pipe, is put in the hole. A thick copper plate of dimensionsis 50 cm x 50 cm welded to the lower end of the copper rod and it is buried in the ground. The plate is surrounded by a mixture of charcoal and salt to make a good earth connection. Solution 20.<\/strong><\/span><\/p>\n If the live wire of a faulty appliance comes in to direct contact with the metallic case due to some reason then the appliance acquires the high potential of live wire. This may results in shock if any person touches the body of appliance. But if the appliance is earthed then as soon as the live wire comes in to contact with the metallic case, high current flows through the case to the earth. The fuse connected to the appliance will also blows off, so the appliance get disconnected.<\/p>\n Solution 21.<\/strong><\/span><\/p>\n (a) The fuse must be connected in the live wire only. If the fuse is in the neutral wire, then although the fuse burns due to the flow of heavy current, but the appliance remains at the supply voltage so that on touching the appliance current flows through the appliance to the person touching it. Solution 22.<\/strong><\/span><\/p>\n The paint provides an insulating layer on the metal body of the appliance. To make earth connection therefore, the paint must be removed from the body part where connection is to be made.<\/p>\n Solution 23.<\/strong><\/span><\/p>\n Solution 25.<\/strong><\/span><\/p>\n (a) The three wires are: Live wire, Earth wire and Neutral wire. Solution 26.<\/strong><\/span><\/p>\n One may get an electric shock from an electrical gadget in the following two cases:<\/p>\n Solution 27.<\/strong><\/span><\/p>\n Power circuit carries high power and costly devices. If there is some unwanted power signal (noise) in the wire it can damage the device. To reduce this effect earth is necessary. Solution 28.<\/strong><\/span><\/p>\n A high tension wire has a low resistance and large surface area.<\/p>\n Solution 29.<\/strong><\/span><\/p>\n To carry larger current, the resistance of the wire should be low, so its area of cross section should be large. Therefore 15 A current rated wire will be thicker.<\/p>\n Solution 30.<\/strong><\/span><\/p>\n (a) Switches 2 and 3. Solution 31.<\/strong><\/span>
\nAt a power generating station, the electric power is generated at 11 kV. From here, the alternating voltage is transmitted to the grid sub-station and stepped up to 132 kV using a step-up transformer. It is then transmitted to the main sub-station where the voltage is stepped down to 33 kV using a step-down transformer and is then transmitted to the intermediate sub-station. At the intermediate sub-station, the voltage is stepped down to 11 kV using a step-down transformer and is transmitted to the city sub-station, where the voltage is further stepped down to 220 V and is supplied to our houses.<\/p>\n
\n(b) Step-down transformer<\/p>\n\n
\n(c) The switch is connected in the live wire.<\/p>\n
\nIts current rating is\u00a0\u2248 50 A.<\/p>\n\n
\nIts value in S.I. unit is 1kWh = 3.6 x 106<\/sup>J.<\/p>\n
\nAdvantages of ring system over tree system<\/p>\n\n
\n<\/p>\n
\nIn set B, the bulbs are connected in parallel. Thus, each bulb gets connected to its voltage rating (= 220 V) and even when the fuse of one bulb blows off, others remain unaffected and continue to glow.<\/p>\n
\nHint: The main fuse is connected in live wire so that if the current exceeds its rating, the fuse melts and breaks the circuit; thus, preventing the excessive current from flowing into the circuit.<\/p>\n
\nHint: On connecting the electrical appliances in parallel, each appliance works independently without being affected whether the other appliance is switched on or off.<\/p>\n
\nHint: The electric meter in a house records the amount of electrical energy consumed in a house.<\/p>\n
\nAn alloy of lead and tin is used as a material of fuse because it has low melting point and high resistivity.<\/p>\n
\n(b) A fuse wire is made of an alloy of lead and tin. If the current in a circuit rises too high, the fuse wiremelts
\n(c) A fuse is connected in series with the live wire.
\n(d) Higher the current rating, Thicker is the fuse wire.<\/p>\n
\n<\/p>\n
\n<\/p>\n
\n<\/p>\n
\n
\nOn the other hand, if switch is connected in the neutral wire, then in ‘off’ position, no current passes through the bulb. But the appliance remains connected to the high potential terminal through the live wire.
\n
\nThus, if the switch is connected in the neutral wire, it can be quite deceptive and even dangerous for the user.
\nPrecaution while handling a switch: A switch should not be touched with wet hands.<\/p>\n
\n
\nThe bulb can now be switched on independently by either the switch S1<\/sub>\u00a0or the switch S2<\/sub>. If the switch S1<\/sub>\u00a0is operated, the connection ‘ab’ is changed to ‘bc’, which completes the circuit and the bulb lights up [Fig. (b)].
\n<\/p>\n
\n
\nSimilarly if the bulb is in on position as shown in Fig. (b) or (c), one can switch off the bulb either from the switch S1<\/sub>\u00a0or the switch S2<\/sub>.<\/p>\n
\nIn this three way pin plug, the top pin is for earthing (E), the live pin (L) in on the left and the neutral pin (N) is on the right.
\n<\/p>\n
\n
\nHere E signifies the earth pin,
\nL is for live wire, and
\nN is for neutral wire.<\/p>\n\n
\n<\/p>\n
\n(b) Terminal 1 is connected to the outer metallic case of the appliance.
\n(c) The fuse is connected to live wire joined to 3 so that in case of excessive flow of current fuse melts first and breaks down the circuit to protect appliances.<\/p>\n
\nTo keep the ground damp, water is poured through the pipe from time to time. This forms a conducting layer between the plate and the ground. The upper end of the copper rod is joined to the earth connection at the kWh meter.<\/p>\n
\n(b) Metallic case of the appliance should be earthed.<\/p>\n\n
\n(b) The heating element of geyser should be connected to live wire and neutral wire.
\n(c) The metal case should be connected to earth wire.
\n(d) The switch and fuse should be connected to live wire.<\/p>\n\n
\nPreventive measure:<\/strong> The fuse must always be connected in the live wire.<\/li>\n
\nPreventive measure:<\/strong> Proper ‘earthing’ of the electric appliance should be done.<\/li>\n<\/ol>\n
\nLighting circuit carries low power (current).So, we ignore the earth terminal.<\/p>\n
\n(b) The lamps are connected in series.<\/p>\n
\n(a)
\n
\n(b)<\/p>\n