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Samar shah
@samar-shah
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Joined: Jun 14, 2021
Last seen: Jul 17, 2023
Topics: 0 / Replies: 2321
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Answer to: “The ignition temperature of a fuel is 80°C”. What does this mean?

If ignition temp of a fuel is 80°C, this means that minimum 80°C is required for the ignition of the fuel.

5 years ago
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Answer to: Define ignition temperature of a fuel.

Ignition temperature of fuel can be defined as the minimum temperature to which a fuel must be heated so that it may catch fire and start burning.

5 years ago
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Answer to: “The calorific value of cooking gas (LPG) is 50 kJ/g”. What does it mean?

Calorific value of LPG is 50kJ/gm means that if 1 gram of LPG is burnt completely, then it will produce 50kJ of heat energy.

5 years ago
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Answer to: Define calorific value of a fuel.

The amount of heat produced by burning 1 gram of a fuel completely is known as its calorific value.

5 years ago
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Answer to: A domestic lighting circuit has a fuse of 5 A. If the mains supply is at 230 V, calculate the maximum number of 36 W tube lights that can be safely used in this circuit.

Let the maximum number of tube-lights be y. Power of y tube-lights, P = 36y V = 230V, I = 5A We know that P = VI 36y = 230 x 5 36y = 1500 ...

5 years ago
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Answer to: (a) Explain why, it is more dangerous to touch the live wire of a mains supply rather than the neutral wire. (b) Why is it safe for birds to sit on naked power lines fixed atop tall electric poles?

(a) It is more dangerous to touch the live wire rather than the neutral wire because live wire has a high potential of 220V, where as neutral wire has...

5 years ago
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Answer to: What is the main difference between the wiring of an electric bulb and a socket for using an electric iron in a domestic electric circuit? What is the reason for this difference?

No earth connection is required for the bulb connection as it does not draw heavy current and we hardly touch it. A socket for using an electric iron ...

5 years ago
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Answer to: An electric kettle rated as 1200 W at 220 V and a toaster rated at 1000 W at 220 V are both connected in parallel to a source of 220 V.

P1 = 1200W, P2 = 1000W V = 220V Fuse rating = 9A We know, P = VI Total current required I = = (P1+P2)/V = (1200+1000)/220 = 10A ...

5 years ago
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Answer to: Which of the following circuits will still be dangerous even if the fuse blows off and electric iron stops working during a short circuit?

Circuit A is not dangerous after fuse blows because fuse is fitted in the live wire; but circuit B is dangerous even if fuse blows because the fuse is...

5 years ago
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Answer to: A vacuum cleaner draws a current of 2 A from the mains supply. (a) What is the appropriate value of the fuse to be fitted in its circuit?

(a) The appropriate value of the fuse to be fitted in the circuit is 2.5A or 3A. (b) If a 13A fuse is fitted in the circuit, it will not protect the...

5 years ago
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Answer to: Three appliances are connected in parallel to the same source which provides a voltage of 220 V. A fuse connected to the source will blow if the current from the source exceeds 10 A.

P1 = 60 W, P2 = 1200W, P3 = 500W Fuse rating = 10A V = 220V We have, P = VI Total power = 60 + 1200 + 500 = 1760W Therefore, 1760 = 22...

5 years ago
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Answer to: (a) Why are fuses fitted in the fuse box of a domestic electricity supply? (b) What device could be used in place of the fuses?

(a) Fuses are fitted in the fuse box of a domestic electricity supply to protect the whole wiring of the house when excessive current flows in the cir...

5 years ago
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Answer to: (a) What current is taken by a 3 kW electric geyser working on 240 V mains? (b) What size fuse should be used in the geyser circuit?

(a) P = 3kW = 3000W V = 240V P = V x I I = = = 12.5 A. (b) A 13A fuse should be used in the geyser circuit.

5 years ago
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Answer to: What is the function of an earth wire? Why is it necessary to earth the metallic bodies of electrical appliances?

When the live wire of a faulty appliance comes in direct contact with its metallic case, which has been earthed, the large current passes directly to ...

5 years ago
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Answer to: Explain the importance of using in a household electric circuit (i) fuse, and (ii) earthing wire.

(i) A fuse is one of most important protection devices, which is used for avoiding the damages happening due to over load or short circuit. (ii) An ...

5 years ago
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