Chapter 14 - Sources of Energy Page no - 243 Solution 1 Concept Comprehension :- A good source of energy fulfils the following criteria: (i) It produces a lot of heat per unit mass. (ii) It does a huge amount of work per unit volume or mass. (iii) It is easily accessible. (iv) It is easy to store and transport. (v) It is economical. (vi) It produces less amount of smoke. Solution 2 A good fuel produces a huge amount of heat on burning, does not produce a lot of smoke, and is easily available. Solution 3 Concept Comprehension:- Natural gas can be used for heating and cooking food because it is a clean source of energy. It produces a huge amount of heat on burning. Although it is highly inflammable, it is easy to use, transport, and It does not produce huge amount of smoke on burning. Chapter 14 - Sources of Energy Page no - 248 Solution 1 The disadvantages of fossil fuels are as follows: Concept Comprehension:- (a) Fos...
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Chapter 13 - Magnetic Effects of Current Page no - 224 Solution 1 A compass needle is a small bar magnet. When it is brought near a bar magnet, its magnetic field lines interact with that of the bar magnet. Hence, a compass needle shows a deflection when brought near a bar magnet. Concept Comprehension: Magnetic fields interact with each other. Interaction of magnetic field of earth and that of the compass needle is used to find directions. Chapter 13 - Magnetic Effects of Current Page no - 228 Solution 1 Magnetic field lines of a bar magnet emerge from the north pole and terminate at the south pole. Inside the magnet, the field lines emerge from the south pole and terminate at the north pole, as shown in the given figure. Concept Comprehension: - Note that magnetic field lines never intersect each other. Solution 2 The properties of magnetic lines of force are as follows. 1. Outside a magnet, magnetic field lines are directed from N...