Ask questions which are clear, concise and easy to understand.

A wire's diameter is doubled. What will be the new resistance?

Posted by Pranzal Kumar Sinha (May 23, 2017 2:08 p.m.) (Question ID: 5445)

  • Answers:
  • Ans. 

    We know that 

    Resistance R = {tex}\rho {L\over A}{/tex}

    Where {tex}\rho{/tex} is resistivity of material

    L is length of wire

    A is area of Cross-section of wire

    Area A = {tex}\pi r^2{/tex}

    If we double the Diameter it means radius is also doubled 

    So now Area = {tex}\pi (2r)^2= 4\pi r^2{/tex} = 4A

    So  New Resistance R' = {tex}\rho {L\over 4A} = {R\over 4}{/tex}

    Means new resistance will be {tex}({1\over 4})^{th}{/tex} of old resistance .

     

    Answered by Naveen Sharma (May 23, 2017 2:55 p.m.)
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Why nitrogen is filled in  the  cyllinders of scuba divers if it blocks our capillaries.

Posted by Deepanshu Banga (May 23, 2017 12:18 p.m.) (Question ID: 5444)

The value of tan 90' is not defined  . Why ?

Posted by pritam mall (May 23, 2017 8:26 a.m.) (Question ID: 5443)

  • Answers:
  • Tangent of an angle is equal to the perpendicular divided by the base, As the angle approaches 90 degree, the value of the perpendicular starts to rise at abnormally higher rate but the value of the base remains same.

    At 90 degree, there will be no triangle as the perpendicular and hypotenuse will never meet or meet at infinity and in that case perpendicular and the hypotenuse both wil be infinie..

    tan 90 will be infinite

    Answered by Payal Singh (May 23, 2017 8:35 a.m.)
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If cos (a+b)=0, then sin (a-b)=

1) cos 2b

2) cos b

3) sin 2a

4) sin a

Posted by Sudhanshu Baranwal (May 23, 2017 8:25 a.m.) (Question ID: 5442)

  • Answers:
  • 1) cos 2b

    Explanation:

    cos (a+b) =0

    => cos (a+b) = cos 90

    => a+b = 90

    => a = 90- b

    Now

    sin(a+b)

    = sin(90-b-b)

    = sin(90-2b)

    = cos 2b     [as sin (90 - x) = cos  x]

    Answered by Payal Singh (May 23, 2017 8:34 a.m.)
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Resistors which are connected in series have different potential difference. Why ?

Posted by pritam mall (May 23, 2017 8:21 a.m.) (Question ID: 5441)

The correct one is:

1) Bring the book me that is lying on the table.

2) Bring the book that lying on the table to me.

3) Bring to me the book that is lying on the table.

4) Bring me the book that is lying on the table.

Posted by Sudhanshu Baranwal (May 23, 2017 8:20 a.m.) (Question ID: 5440)

  • Answers:
  • 4) Bring me the book that is lying on the table.

    Answered by Payal Singh (May 23, 2017 8:23 a.m.)
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An acidic oxide is formed by the element: 

1) H

2) K

3) Ca

4) C

Posted by Sudhanshu Baranwal (May 23, 2017 8:16 a.m.) (Question ID: 5439)

  • Answers:
  • 4. C

    Explanation: Those oxides which form acidic solutions on reaction with water are called acidic oxides, (or sometimes acid anhydrides). The acidic oxides are the oxides of the non-metal elements.

    Answered by Payal Singh (May 23, 2017 8:21 a.m.)
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A white precipitate is obtained by adding common salt solution into a solution of:

1) AgNO3

2) KNO3

3) NH4NO3

4) Ba(NO3)2

Posted by Sudhanshu Baranwal (May 23, 2017 8:15 a.m.) (Question ID: 5438)

  • Answers:
  • 1) AgNO3

    Explanation:

    NaCl + AgNO3{tex}\to{/tex} NaNO+ AgCl

     

    Silver chloride is  (White precipitate)

    Answered by Payal Singh (May 23, 2017 8:28 a.m.)
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How can the  Story of helen keller inspire others? 

Posted by Sagar Solanki (May 23, 2017 7:44 a.m.) (Question ID: 5437)

  • Answers:
  • Ans. The life story of a deaf and blind person makes for an inspirational read because it bears testimony to the powers of the human will and endurance in the face of adversities. It is the account of a human being's exceptional powers of perseverance which enables the person to overcome all odds to triumph in life.

    Helen Keller could neither see nor hear but her achievements belie her physical limitations. Her intellectual capabilities and aesthetic sensibilities could not be constrained by her physical disadvantages, her thirst for knowledge was unquenchable and her love of life, human or natural, boundless.

    It is interesting and inspiring to read the story of her life because she triumphed against all adversities with grace and learned from her mistakes. Nothing could stop her from charting the course of her life which is a lesson for us in overcoming our obstacles. She took life in her stride and strove towards progress.

    There is a lot to learn from even reading about a person without the powers of vision or hearing but looks at life in such a positive manner. It is easy to complain or give up, the real test lies in enduring and continuing until we win.

    The greatness in her personality stemmed from the desire to overcome all that obstructed her path to progress. She was determined to succeed and she did, this is what makes her tale an inspiring story

    Answered by Naveen Sharma (May 23, 2017 10:14 a.m.)
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can u tell me the translation of the 3rd lesson for CBSE Arabic 

Posted by ashita prakash (May 22, 2017 10:46 p.m.) (Question ID: 5436)

2/3 of 3/4 of 18

Posted by akash pradeepan (May 22, 2017 10:25 p.m.) (Question ID: 5435)

  • Answers:
  • {tex}{2\over 3}\times {3\over 4}\times 18 =9{/tex}

    Answered by Payal Singh (May 22, 2017 11:24 p.m.)
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Neither of them _______ come.

Which will be correct option to fill in the blank?

1) was

2) has

3)were

4)have

Posted by Sudhanshu Baranwal (May 22, 2017 8:34 p.m.) (Question ID: 5434)

  • Answers:
  • Neither of them has come.

    Answered by Payal Singh (May 22, 2017 10:29 p.m.)
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  • Neither of them has come. 

    Answered by Pranzal Kumar Sinha (May 22, 2017 10:16 p.m.)
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I need Note's of Political science 

Posted by ChandrPal Singh Adbala (May 22, 2017 7:26 p.m.) (Question ID: 5433)

what are the funcitons and importace of the following

  1. cancelled cheque
  2. pay in slip
  3. Draft slip
  4. cash memo
  5. invoice and bill
  6. voucher
Posted by govind gulia (May 22, 2017 5:18 p.m.) (Question ID: 5432)

Explain the reason of depresion in frezing point

Posted by Pawan Kabdal (May 22, 2017 4:55 p.m.) (Question ID: 5431)

  • Answers:
  • Freezing point depression is the phenomena that describes why adding a solute to a solvent results in the lowering of the freezing point of the solvent. When a substance starts to freeze, the molecules slow down due to the decreases in temperature, and the intermolecular forces start to take over. The molecules will then arrange themselves in a pattern, and thus turn into a solid. For example, as water is cooled to the freezing point, its molecules become slower and hydrogen bonds begin to "stick" more, eventually creating a solid. If salt is added to the water, the Na+ and Cl- ions attract to the water molecules and interfere with the formation of the large network solid known as ice. In order to achieve a solid, the solution must be cooled to an even lower temperature.

    The freezing point depression can also be explained in terms of vapor pressure. Adding solute to a solvent will essentially dilute the solvent molecules, and according to Raoult's law, this leads to a decrease in vapor pressure. Considering the fact that the vapor pressure of the solid and liquid forms must be the same at freezing point, because otherwise the system would not be at equilibrium, the lowering of the vapor pressure leads to the lowering of the temperature at which the vapor pressures of the liquid and frozen forms of the solution will be equal.

     

     The freezing point depression can be calculated by the formula:

    {tex}\Delta T_f=i\times K_ f\times molality{/tex}

    In this equation,

    {tex}\Delta T_f{/tex} is the freezing point depression,

    Kf is the freezing point depression constant,  and i is the van 't Hoff factor.

    The freezing point depression constant changes depending on the solvent, and the van 't Hoff factor accounts for the number of particles that a dissolving solute creates in solution.

     

    Answered by Payal Singh (May 23, 2017 11:07 a.m.)
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Write the character sketch of lilliputian emperor

Posted by Shubham Roy (May 22, 2017 1:54 p.m.) (Question ID: 5430)

  • Answers:
  • Ans. The emperor - The ruler of Lilliput. Like all Lilliputians, the emperor is fewer than six inches tall. His power and majesty impress Gulliver deeply, but to us he appears both laughable and sinister. Because of his tiny size, his belief that he can control Gulliver seems silly, but his willingness to execute his subjects for minor reasons of politics or honor gives him a frightening aspect. He is proud of possessing the tallest trees and biggest palace in the kingdom, but he is also quite hospitable, spending a fortune on his captive’s food. The emperor is both a satire of the autocratic ruler and a strangely serious portrait of political power.

    Answered by Naveen Sharma (May 22, 2017 2:05 p.m.)
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What is the difference b/was gas and vapour? give two example

 

Posted by Sanjeev Singh Tomar Tomar (May 22, 2017 1:48 p.m.) (Question ID: 5428)

  • Answers:
  • Ans.

    • Gas is one of the 4 states of matter which are solid, liquid, gas and plasma, vapor does not classify as such. It is just a substance. it is gaseous form.
    • Vapor can turn back and forth into liquid and solid states but a gas cannot
    • Gases cannot be see while vapors are visible
    • Vapors settle down on ground while gases do not
    Answered by Naveen Sharma (May 22, 2017 2:09 p.m.)
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Explain details about chacha nehra award

Posted by prabhnoor kaur (May 22, 2017 1:24 p.m.) (Question ID: 5427)

  • Answers:
  • Ans. Objective: The aim is to identify, recognize, nurture and develop the extraordinary talent among the students studying in class VIII onwards in sports and games. This will help in the development of sports activities at the school level and buttress the importance of mental and physical health among the children. The financial support in the form of scholarship will motivate the students to excel in their sports activities.

    Numbers and Value of each scholarship: There are 50 scholarships each year at the rate of Rs.500/- per month to all identified sports talents in class IX-XII based on the performance at national level in various disciplines of CBSE Inter School Sports and Games. Cunently, there are 14 disciplines and number of scholarships available in each discipline is enclosed .

    Duration: The scholarship shall be awarded from the commencement of Class IX (or higher class) and up to class XII (max. four years) subject to fulfillment of following conditions.

    • Visible level of improvement in performance in the skills of the concerned discipline.
    • Passing of each level of classe examination.
    • A candidate selected for the award in Class VIII but has not qualified for admission to Class IX shall not be eligible for the award.
    • A candidate who has been discontinued from the rolls of an institution or has been rusticated shall forfeit the award.
    Answered by Naveen Sharma (May 22, 2017 1:45 p.m.)
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A train 100m long moving on a straight line track passes in 5sec.find the speed of the train and the time taken to cross a bridge  500m long

Posted by Akshyata Singh (May 22, 2017 10:29 a.m.) (Question ID: 5426)

  • Answers:
  • Ans. length of train = 100 m 

    To pass a pole train ll cover the distance equal to its length

    So distance cover by train = 100 m

    Time taken = 5 s

    Speed of train = {tex}distance \ cover \over time \ taken{/tex} = {tex}100 \over 5 {/tex} = 20 m/s

     

    Total distance to cover to cross a bridge = length of bridge + length of train = 500 + 100 = 600 m

    Speed = 20 m/s

    time taken = {tex}distance \ cover \over speed{/tex} = {tex}600 \over 20 {/tex} =  30 s

    Answered by Naveen Sharma (May 22, 2017 12:53 p.m.)
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What do you understand by non uniform acceleration? 

Posted by Pradhyumn Soni (May 22, 2017 10:13 a.m.) (Question ID: 5424)

  • Answers:
  • Non-uniform Acceleration:- A body is said to have a non-uniform acceleration if its velocity increases by unequal amounts in equal intervals of time. Eg The speed or velocity of a car running on a crowded city road changes continuously.

    The velocity-time graph of a body having uniform acceleration is a curved line.

    Answered by Payal Singh (May 23, 2017 4:11 p.m.)
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What do you understand by uniform acceleration?

Posted by Pradhyumn Soni (May 22, 2017 10:11 a.m.) (Question ID: 5423)

  • Answers:
  • Uniform Acceleration:- A body is said to have a uniform acceleration if it travels in a straight line and its velocity increases by equal amounts in equal intervals of time. Eg.the motion of a freely falling body is uniformly accelerated.

    The velocity-time graph of a body having uniformly accelerated motion is a straight line.

     

    Answered by Payal Singh (May 23, 2017 4:17 p.m.)
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Describe the case of positive acceleration. 

Posted by Pradhyumn Soni (May 22, 2017 10:10 a.m.) (Question ID: 5422)

  • Answers:
  • If the velocity of a body increases, then the body is said to have a positive acceleration.

    Answered by Payal Singh (May 22, 2017 1:03 p.m.)
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Describe the case of negative  acceleration. 

 

Posted by Pradhyumn Soni (May 22, 2017 10:09 a.m.) (Question ID: 5421)

  • Answers:
  • Negative Acceleration:- If the velocity of a body decreases, then the body is said to have a negative acceleration. Negative Acceleration is also known as retardation or deceleration

    Answered by Payal Singh (May 22, 2017 1:05 p.m.)
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Is it enough to study the ncert textbook only to score good marks in social science?

 

Posted by Lalit Verma (May 22, 2017 9:28 a.m.) (Question ID: 5420)

  • Answers:
  • yes

     

    Answered by SAHIB SINGH (May 22, 2017 3:23 p.m.)
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what are the hobbies of helen keller? why did she enjoy reading? name the first book read by helen keller. who embossed the book for her?

 

Posted by ayush jain (May 22, 2017 7:24 a.m.) (Question ID: 5419)

describe the family of helen keller 

 

Posted by ayush jain (May 22, 2017 7:23 a.m.) (Question ID: 5418)

  • Answers:
  • Ans. Helen Adams Keller was born on June 27, 1880, in Tuscumbia, Alabama. Her family lived on a homestead, Ivy Green, that Helen's grandfather had built decades earlier.

    She had two younger siblings, Mildred Campbell and Phillip Brooks Keller, two older half-brothers from her father's prior marriage, James and William Simpson Keller.Her father, Arthur H. Keller,spent many years as an editor for the Tuscumbia North Alabamian, and had served as a captain for the Confederate Army.Her paternal grandmother was the second cousin of Robert E. Lee. Her mother, Kate Adams, was the daughter of Charles W. Adams.Though originally from Massachusetts, Charles Adams also fought for the Confederate Army during the American Civil War, earning the rank of colonel (and acting brigadier-general).

    Her paternal lineage was traced to Casper Keller, a native of Switzerland.One of Helen's Swiss ancestors was the first teacher for the deaf in Zurich.

    Answered by Naveen Sharma (May 23, 2017 10:13 a.m.)
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how did helen keller loser her eye sight ?

 

 

Posted by ayush jain (May 22, 2017 7:22 a.m.) (Question ID: 5417)

  • Answers:
  • Ans. When she was nineteen months old she became sick and lost her eyesight and hearing. The doctor didn't know what it was, so he called it a "congestion of the stomach and brain." Some people say that it was scarlet fever or meningitis

    Answered by Naveen Sharma (May 22, 2017 9:51 a.m.)
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life of helen keller is inspirational explain 

 

Posted by ayush jain (May 22, 2017 7:21 a.m.) (Question ID: 5416)

  • Answers:
  • Ans. The life story of a deaf and blind person makes for an inspirational read because it bears testimony to the powers of the human will and endurance in the face of adversities. It is the account of a human being's exceptional powers of perseverance which enables the person to overcome all odds to triumph in life. Helen Keller could neither see nor hear but her achievements belie her physical limitations.

    Her intellectual capabilities and aesthetic sensibilities could not be constrained by her physical disadvantages, her thirst for knowledge was unquenchable and her love of life, human or natural, boundless. It is interesting and inspiring to read the story of her life because she triumphed against all adversities with grace and learned from her mistakes. Nothing could stop her from charting the course of her life which is a lesson for us in overcoming our obstacles. She took life in her stride and strove towards progress.

    There is a lot to learn from even reading about a person without the powers of vision or hearing but looks at life in such a positive manner. It is easy to complain or give up, the real test lies in enduring and continuing until we win. The greatness in her personality stemmed from the desire to overcome all that obstructed her path to progress. She was determined to succeed and she did, this is what makes her tale an inspiring story.

    Answered by Naveen Sharma (May 22, 2017 1:49 p.m.)
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What is the utility of text box in insert tab

Posted by Raj Pandey (May 21, 2017 11:20 p.m.) (Question ID: 5415)

  • Answers:
  • Ans. A text box is an object that you can add to your Word document to emphasize or set off your text.
    To add a text box, click Insert > Text > Text Box.

    Answered by Naveen Sharma (May 22, 2017 2:22 p.m.)
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Explain the life cycle of silk moth. 

Posted by rizwan khan (May 21, 2017 11:16 p.m.) (Question ID: 5414)

  • Answers:
  • Life Cycle – Silk Moth: The life history of a silk moth starts when a female silk moth lays eggs. The larvae or caterpillars hatched from the eggs of the silk moth.

    These silkworms feed on fresh mulberry leaves the silkworm grows in size and then becomes a pupa.

    In the pupa stage, it weaves a net to hold itself. It then swings its head from side to side, secreting a fibre that hardens on contact with air. This fibre is made of a protein and becomes the silk fibre. The caterpillar covers itself completely with silk fibre and turns into a pupa, this covering is known as the cocoon.

    The moth continues to develop within the cocoon. The silk thread or yarn is obtained from the silk moth’s cocoon.

    Answered by Payal Singh (May 22, 2017 2:18 p.m.)
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