A coil of insulated copper wire is connected to a galvanometer.
[question] Question. A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is (i) pushed into the coil (ii) withdrawn from inside the coil, (iii) held stationary inside the coil ? [/question] [solution] solution: (i) When a bar magnet is pushed into the coil, induced current flows through the coil due to the phenomenon of electromagnetic induction. This induced current is indicated by the deflection of the needle of the galvanometer inserted into the co...
Read More →Name some devices in which electric motors are used.
[question] Question. Name some devices in which electric motors are used. [/question] [solution] solution: Pump sets, electric cars, rolling mills, electric fans, hair dryer, etc. [/solution]...
Read More →A freely falling object eventually stops on reaching the ground.
[question] Question. A freely falling object eventually stops on reaching the ground. What happens to its kinetic energy ? [/question] [solution] Solution: The kinetic energy on reaching the ground changes into heat energy, sound energy, etc. and therefore gets dissipated to the ground and air [solution]...
Read More →Answer the following questions briefly.
[question] Question. Answer the following questions briefly. (i) What are tectonic plates? (ii) Which continents of today were part of the Gondwana land? (iii) What is the bhabar? (iv) Name the three major divisions of the Himalayas from north to south. (v) Which plateau lies between the Aravali and the Vindhyan ranges? (vi) Name the island group of India having coral origin. [/question] [solution] Solution: (i) The convectional currents present below the solid layer of Earth’s crust split the c...
Read More →To what extent does government regulation and new laws solve problems of pollution?
[question] Question. To what extent does government regulation and new laws solve problems of pollution? Discuss one example each of the success and failure of legislation to change the quality of (a) public life (b) private life [/question] [solution] Solution: Government laws play an important role in controlling the rates of pollution in a city. However, simply passing laws is not enough. They need to be properly enforced as well. It is also a fact that people tend to find ways of getting aro...
Read More →Draw a labelled diagram of an electric motor.
[question] Question. Draw a labelled diagram of an electric motor. Explain its principle and working. What is the function of a split-ring in an electric motor ? [/question] [solution] solution: An electric motor is a rotating device that converts electrical energy to mechanical energy. Principle involved : It is based on the fact that a current-carrying coil experiences equal and opposite forces on its edges which rotates it continuously. Construction : An electric motor consists of a rectangul...
Read More →Find the energy in kWh
[question] Question. Find the energy in kWh consumed in 10 hours by four devices of power 500 W each. [/question] [solution] Solution: Total power of 4 devices = 4 × 500 W $=2000 \mathrm{~W}=\frac{2000 \mathrm{~W}}{1000}=2 \mathrm{~kW}$ Time $=10 \mathrm{~h}$ Energy consumed = Power × time = 2 kW × 10 h = 20 kWh [/solution]...
Read More →Choose the right answer from the four alternatives given below.
[question] Question. Choose the right answer from the four alternatives given below. (i) A landmass bound by sea on three sides is referred to as (a) Coast (c) Peninsula (b) Island (d) None of the above (ii) Mountain ranges in the eastern part of India forming its boundary with Myanmar are collectively called as (a) Himachal (c) Purvachal (b) Uttarakhand (d) None of the above (iii) The western coastal strip, south of Goa is referred to as (a) Coromandel (c) Kannad (b) Konkan (d) Northern Circar ...
Read More →Soni says that the acceleration in an object could be zero
[question] Question. Soni says that the acceleration in an object could be zero even when several forces are acting on it. Do you agree with her ? Why ? [/question] [solution] Solution: Yes, we do agree. When a number of forces act on a body, such that they constitute balanced forces, then net force acting on the body is zero. In such a situation no acceleration occurs in the object. [/solution]...
Read More →Think you are sitting in a chamber with your back to one wall.
[question] Question. Think you are sitting in a chamber with your back to one wall. An electron beam moving horizontally from back wall towards the front wall, is deflected by a strong magnetic field, to your right side. What is the direction of magnetic field ? [/question] [solution] solution: Movement of electron beam from back wall to the front wall is equivalent to the flow of electric current from front wall to the back wall. The deflection of the beam means, the force is acting towards our...
Read More →When is the force experienced by a current-carrying
[question] Question. When is the force experienced by a current-carrying conductor placed in magnetic field the largest ? [/question] [solution] solution: When current-carrying conductor is placed perpendicular to the magnetic field. [/solution]...
Read More →How does a solenoid behave like a magnet ?
[question] Question. How does a solenoid behave like a magnet ? Can you determine the north and south poles of a current-carrying solenoid with the help of a bar magnet ? Explain. [/question] [solution] solution: When electric current flows through a solenoid, magnetic field is set up around the solenoid. One end of the solenoid behaves as north pole and the other end of the solenoid behaves as south pole. To determine the north and south poles of a current-carrying solenoid, bring the north pol...
Read More →List three sources of magnetic fields.
[question] Question. List three sources of magnetic fields. [/question] [solution] solution: (i) A permanent magnet. (ii) A current-carrying conductor. (iii) A current-carrying solenoid. [/solution]...
Read More →Calculate the work required to be done
[question] Question. Calculate the work required to be done to stop a car of $1500 \mathrm{~kg}$ moving at a velocity of $60 \mathrm{kmh}^{-1}$. [/question] [solution] Solution: Given, mass of car, $\mathrm{m}=1500 \mathrm{~kg}$; velocity of car, $\mathrm{v}=60 \mathrm{kmh}^{-1}=60 \times \frac{5}{18}=\frac{50}{3} \mathrm{~m} / \mathrm{s}$ Work done $=$ Change in kinetic energy of the car or $W=\frac{1}{2} m v^{2}-\frac{1}{2} m u^{2}=\frac{1}{2} m\left(v^{2}-u^{2}\right)$ or $W=\frac{1}{2}(1500)...
Read More →State whether the following statements are true or false.
[question] Question. State whether the following statements are true or false. (1) An electric motor converts mechanical energy into electrical energy. (2) An electric generator works on the principle of electromagnetic induction. (3) The field at the centre of a long circular coil carrying current will be parallel straight lines. (4) A wire with a green insulation is usually the live wire. [/question] [solution] solution: (1)False. It converts electrical energy into mechanical energy. (2) True ...
Read More →An object of mass, m is moving with a constant velocity, ?
[question] Question. An object of mass, m is moving with a constant velocity, v. How much work should be done on the object in order to bring the object to rest ? [/question] [solution] Solution: Work done to bring the object to rest = change in kinetic energy of the object $=0-\frac{1}{2} \mathrm{mv}^{2}=-\frac{1}{2} \mathrm{mv}^{2}$ [/solution]...
Read More →At the time of short-circuit,
[question] Question. At the time of short-circuit, the current in the circuit (1) Reduces substantially (2) Does not change (3) Increases heavily (4) Varies continuously [/question] [solution] solution: Short-circuit takes place when the live wire and the neutral wire come into direct contact, the resistance in the circuit becomes very low and the current in the circuit abruptly increases. Thus, option (3) is correct. [/solution]...
Read More →Illustrate the law of conservation of energy by discussing the energy changes which occur when we draw a pendulum bob to one side and allow it to oscillate.
[question] Question. Illustrate the law of conservation of energy by discussing the energy changes which occur when we draw a pendulum bob to one side and allow it to oscillate. Why does the bob eventually come to rest ? What happens to its energy eventually ? Is it a violation of the law of conservation of energy ? [/question] [solution] Solution: When the pendulum bob is pulled (say towards left), the energy supplied is stored in it in the form of potential energy (PE) on account of its higher...
Read More →The essential difference between
[question] Question. The essential difference between an AC generator and a DC generator is that (1) AC generator has an electromagnet while a DC generator has permanent magnet. (2) DC generator will generate a higher voltage. (3) AC generator will generate a higher voltage. (4) AC generator has slip rings while the DC generator has a commutator. [/question] [solution] solution: An AC generator has slip rings while a DC generator has split-ring commutator. Thus, option (4) is correct. [/solution...
Read More →How would you explain the rise of Napoleon?
[question] Question. How would you explain the rise of Napoleon? [/question] [solution] Solution: The rise of Napoleon came right after the fall of the Directory in 1796. The Directors often clashed with the legislative councils, who then made attempts to dismiss them. The Directory was highly politically unstable; hence, Napoleon rose to power as a military dictator. Earlier, the Jacobins had overthrown King Louis XVI and established governance on their own module; but Robespierre’s administrat...
Read More →Would you agree with the view that the message of universal rights was beset with contradictions?
[question] Question. Would you agree with the view that the message of universal rights was beset with contradictions? Explain [/question] [solution] Solution: The message of universal rights was beset with contradictions. Many ideals in the “Declaration of Rights of Man and Citizen” were replete with dubious meanings. For example, “the law has the right to forbid only actions injurious to society” had nothing to say about criminal offences against other individuals. Also, the declaration stated...
Read More →Draw up a list of democratic rights we enjoy today
[question] Question. Draw up a list of democratic rights we enjoy today whose origins could be traced to the French Revolution. [/question] [solution] Solution: Democratic rights that we enjoy today whose origins can be traced to the French Revolution are: freedom of expression, right to equality, right to freedom, right to assemble and form unions (as long as they are not a threat to national security and peace). [/solution]...
Read More →Describe the legacy of the French Revolution for the peoples
[question] Question. Describe the legacy of the French Revolution for the peoples of the world during the nineteenth and twentieth centuries. [/question] [solution] Solution: The French Revolution bore a rich legacy for the peoples of the world during the nineteenth and twentieth centuries because it was the first national movement that adopted the ideals of “liberty, equality and fraternity”. These ideas became the basic tenets of democracy for every nation in the 19th and the 20th century. The...
Read More →Which groups of French society benefited from the revolution?
[question] Question. Which groups of French society benefited from the revolution? Which groups were forced to relinquish power? Which sections of society would have been disappointed with the outcome of the revolution? [/question] [solution] Solution: The richer members of the third estate (the middle class) benefitted the most from the French Revolution. The clergy and the nobility were forced to relinquish power. The poorer sections of society and women would have been disappointed with the o...
Read More →Describe the circumstances leading
[question] Question. Describe the circumstances leading to the outbreak of revolutionary protest in France. [/question] [solution] Solution: Circumstances leading to the outbreak of revolutionary protest in France: A society of estates, and the plight of the third estate French society was divided into three distinct estates: the first estate comprising the clergy, the second estate composed of the nobility, and the third estate made up of tradesmen, merchants, court officials, lawyers, peasants...
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