The magnetic field in a given region is uniform.
[question] Question. The magnetic field in a given region is uniform. Draw a diagram to represent it. [/question] [solution] solution: [/solution]...
Read More →Explain what is referred to as the G-77 countries
[question] Question. Explain what is referred to as the G-77 countries. In what ways can G-77 be seen as a reaction to the activities of the Bretton Woods twins? [/question] [solution] Solution: G-77 countries is an abbreviation for the group of 77 countries that demanded a new international economic order (NIEO); a system that would give them real control over their natural resources, without being victims of neo-colonialism, that is, a new form of colonialism in trade practised by the former c...
Read More →Define 1 watt of power.
[question] Question. Define 1 watt of power. [/question] [solution] Solution: When a work of 1 joule is done in 1 s, the power is said to be one watt. [/solution]...
Read More →Consider a circular loop of wire lying in the plane of the table.
[question] Question. Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right hand rule to find out the direction of magnetic field inside and outside the loop. [/question] [solution] solution: Magnetic field inside the loop is perpendicular to the plane of table and in the downward direction. Outside the loop, magnetic field is perpendicular to the plane of the table and in the upward direction. [/solution]...
Read More →Why do no two magnetic lines of force intersect each other ?
[question] Question. Why do no two magnetic lines of force intersect each other ? [/question] [solution] solution: The tangent at any point on a magnetic field line gives the direction of magnetic field at that point. If two magnetic field lines cross each other, then at the point of intersection, there will be two tangents. Hence, there will be two directions of the magnetic field at the point of intersection. This is not possible. Hence, no two magnetic field lines can cross each other. [/solu...
Read More →What is power ?
[question] Question. What is power ? [/question] [solution] Solution: Power is defined as the rate of doing work. Power $=\frac{\text { work done }}{\text { time taken }}$ [/solution]...
Read More →It is more important to have beauty in the equations of physics than to have them agree with experiments
[question] Question “It is more important to have beauty in the equations of physics than to have them agree with experiments”. The great British physicist P. A. M. Dirac held this view. Criticize this statement. Look out for some equations and results in this book which strike you as beautiful. [/question] [solution] Solution The belief of Dirac is true. Equations representing entire concepts and hold up against experimental results are automatically simple, small and symmetrical, making them g...
Read More →List the properties of magnetic lines of force.
[question] Question. List the properties of magnetic lines of force. [/question] [solution] solution: (i) Magnetic lines of force are closed continuous curves. (ii) The tangent at any point on the magnetic line of force gives the direction of the magnetic field at that point. (iii) Two magnetic lines of force never cross each other. [/solution]...
Read More →Explain the three types of movements or flows within international economic exchange.
[question] Question. Explain the three types of movements or flows within international economic exchange. Find one example of each type of flow which involved India and Indians, and write a short account of it. [solution] Solution: The three types of movements or flows within the international economic exchange are trade flows, human capital flows and capital flows or investments. These can be explained as—the trade in agricultural products, migration of labour, and financial loans to and from ...
Read More →The kinetic energy of an object of mass m,
[question] Question. The kinetic energy of an object of mass m, moving with a velocity of $5 \mathrm{~ms}^{-1}$ is $25 \mathrm{~J}$. What will be its kinetic energy when its velocity is doubled ? What will be its kinetic energy when its velocity is increased three times? [/question] [solution] Solution: Given, velocity of object, $\mathrm{v}=5 \mathrm{~ms}^{-1}$; kinetic energy of an object, $\mathrm{E}_{\mathrm{K}}=25 \mathrm{~J}$ $E_{K}=\frac{1}{2} m v^{2} \quad$ or $\quad 25=\frac{1}{2} \time...
Read More →Draw magnetic field lines around a bar magnet.
[question] Question. Draw magnetic field lines around a bar magnet. [/question] [solution] solution: [/solution]...
Read More →Imagine that you are an indentured Indian labourer in the Caribbean.
[question] Question. Imagine that you are an indentured Indian labourer in the Caribbean. Drawing from the details in this chapter, write a letter to your family describing your life and feelings. [solution] Solution: Indentured Indian labourers in the Carribbean—facts—signed a contract stating that they would return to India after working for five years at a plantation; belonged to eastern Uttar Pradesh, Bihar, central India and the dry districts of Tamil Nadu; migrants took up the overseas job...
Read More →Why does a compass needle get deflected
[question] Question. Why does a compass needle get deflected when brought near a bar magnet ? [/question] [solution] solution: Compass needle is a small magnet which experiences a force in the magnetic field of a bar magnet. Due to this force, it gets deflected. [/solution]...
Read More →Write an expression for the kinetic energy of an object.
[question] Question. Write an expression for the kinetic energy of an object. [/question] [solution] Solution: Kinetic energy, $E_{K}=\frac{1}{2} \mathrm{mv}^{2}$ Where, $m=$ mass of the object $;$ v = speed of the object. [/solution]...
Read More →Though the law gives women equal status in India, many people hold unscientific views on a woman’s innate nature
[question] Question Though the law gives women equal status in India, many people hold unscientific views on a woman’s innate nature, capacity and intelligence, and in practice give them a secondary status and role. Demolish this view using scientific arguments, and by quoting examples of great women in science and other spheres; and persuade yourself and others that, given equal opportunity, women are on par with men. [question] [solution] Solution There is no difference in the ability of women...
Read More →What is meant by the Bretton Woods Agreement?
[question] Question. What is meant by the Bretton Woods Agreement? [solution] Solution: The Bretton Woods Agreement was finalised in July 1944 at Bretton Woods in New Hampshire, USA. It established the International Monetary Fund and the World Bank to preserve global economic stability and full employment in the industrial world. These institutions also dealt with external surpluses and deficits of member nations, and financed post-war reconstructions. [/solution]...
Read More →Explain the following
[question] Question. Explain the following : (1)Why is tungsten used almost exclusively for filament of incandescent lamps ? (2)Why are the conductors of electric heating devices, such as toasters and electric irons, made of an alloy rather than a pure metal ? (3)Why is the series arrangement not used for domestic circuits ? (4)How does the resistance of a wire vary with its cross-sectional area ? (5)Why are copper and aluminium wires usually employed for electricity transmission ? [/question] [...
Read More →Write a note to explain the effects of the following:
[question] Question. Write a note to explain the effects of the following: (a) The British government’s decision to abolish the Corn Laws. (b) The coming of rinderpest to Africa. (c) The death of men of working-age in Europe because of the World War. (d) The Great Depression on the Indian economy. (e) The decision of MNCs to relocate production to Asian countries. [/question] [solution] Solution: (a) The British government’s decision to abolish the Corn Laws resulted in losses for the agricultur...
Read More →What is the kinetic energy of an object ?
[question] Question. What is the kinetic energy of an object ? [/question] [solution] Solution: The energy possessed by a body by virtue of its motion is called kinetic energy [/solution]...
Read More →An electric heater of resistance $8 \Omega$ draws $15 \mathrm{~A}$ from the service mains for 2 hours.
[question] Question. An electric heater of resistance $8 \Omega$ draws 15 A from the service mains for 2 hours. Calculate the rate at which heat is developed in the heater. [/question] [solution] solution: Here, $\mathrm{I}=15 \mathrm{~A}, \mathrm{R}=8 \Omega, \mathrm{t}=2 \mathrm{~h}$ Rate at which heat is developed, i.e, electric power, $\mathrm{P}=\mathrm{I}^{2} \mathrm{R}=(15)^{2} \times 8=1800 \mathrm{~W}$ [/solution]...
Read More →A pair of bullocks exerts a force of 140 N on a plough.
[question] Question. A pair of bullocks exerts a force of 140 N on a plough. The field being ploughed is 15 m long. How much work is done in ploughing the length of the field ? [/question] [solution] Solution: Work done = F × s = 140 × 15 = 2100 J [/solution]...
Read More →Explain how the global transfer of disease in the pre-modern world helped in the colonisation of the Americas.
[question] Question. Explain how the global transfer of disease in the pre-modern world helped in the colonisation of the Americas. [/question] [solution] Solution: The global transfer of disease in the pre-modern world helped in the colonisation of the Americas because the native American Indians were not immune to the diseases that the settlers and colonisers brought with them. The Europeans were more or less immune to small pox, but the native Americans, having been cut off from the rest of t...
Read More →Define 1 J of work.
[question] Question. Define 1 J of work. [/question] [solution] Solution: When a force of 1 N causes a displacement of 1 m, in its own direction, then work done is said to be one joule. [/solution]...
Read More →Which uses more energy,
[question] Question. Which uses more energy, a $250 \mathrm{~W}$ TV set in $1 \mathrm{~h}$, or a $1200 \mathrm{~W}$ toaster in 10 minutes ? [/question] [solution] solution: Energy used by $250 \mathrm{~W}$ TV set in $1 \mathrm{~h}=250 \times 1=250 \mathrm{Wh}$ Energy used by $1200 \mathrm{~W}$ toaster in $10 \mathrm{~min}$. (i.e., $1 / 6 \mathrm{~h})=1200 \times(1 / 6)=200 \mathrm{Wh}$ Thus, a $250 \mathrm{~W}$ TV set uses more energy in $1 \mathrm{~h}$ than a $1200 \mathrm{~W}$ toaster in 10 mi...
Read More →Give two examples of different types of global exchanges which took place before the seventeenth century,
[question] Question. Give two examples of different types of global exchanges which took place before the seventeenth century, choosing one example from Asia and one from the Americas. [solution] Solution: Examples of the different types of global exchanges which took place before the seventeenth century: 1) Textiles, spices and Chinese pottery were exchanged by China, India and Southeast Asia in return for gold and silver from Europe. 2) Gold and foods such as potatoes, soya, groundnuts, tomato...
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