Monday, October 5, 2009

important questions -paper 2

 

IMPORTANT QUESTIONS ------ PHYSICS (SCIENCE)

CLASS    X

 

1.      Distinguish between the terms “overloading and short circuiting” as used in domestic circuits.   (b) Why are the coils of electric toasters made of an alloy rather than a pure metal?

2.      What is meant by dispersion of white light? Describe the formation of rainbow in the sky with the help of a diagram.

3.       What is hypermetropia? Draw ray diagrams to show the image formation of an object by: (i) Hypermetropic eye.  (ii) Correction made with a suitable lens for hypermetropic eye.

4.      Give reason for the following: i)lour of the clear sky is blue.(ii) The sun can be seen about two minutes before actual    sunrise.(iii) We cannot see an object clearly if it is placed very close to the eyes.

5.      What is Presbyopia? Write two causes of this defect.

6.      .Draw a diagram to show the magnetic filed lines around a current carrying solenoid. What do you interpret from the pattern of the field lines?

7.      Difference between real and virtual images.

8.      Write any 4 uses of spherical mirrors.

9.      State the mirror formula.

10.  What is magnification . What is its SI unit.

11.  Draw a ray diagram of image formation when the object is placed in front of a convex lens at different position.

12.  What do you understand by spherical aberration and how it is corrected?

13.  Why do stars twinkle on a clear night?

14.  What is mirage? How does it occur?

15.  What is dispersion? How will you show that sun-light is composes of seven colours?

16.  What is the focal length of a plane mirror?

17.  Draw labelled diagram of human eye and describe its working.

18.  How do we see colours? What is colour blindness?

19.  What do you under stand by “least distance of distinct vision”.

20.  . What is persistence of vision? Write the process where it is used.

21.  Where will the image be formed when the object is placed between the focus and the pole (infinity, pole) of the convex mirror?

22.  With respect to air the refractive index of ice and that of rock salts are 1.31 and 1.54 respectively. Calculate the refractive index of rock salt with respect to ice.

 

 

 

 

23.  With respect to air the refractive index of water and that of benzene are 1.33 and 1.50 respectively. Calculate the refractive index of benzene with respect to water.

24.  A convex mirror used on a truck has 3m radius of curvature. If a bus is located at 5m from this mirror. Find the position, nature and size of the image.

25.  What is accommodation? What is the maximum variation in power of accommodation in human eye?

26.  An object of size 5cm is placed at a distance of 25cm from the pole of a concave mirror of radius of curvature 30cm. Calculate the distance and size of the image formed. What will be the nature of the image?

27.  An object of size 3cm is placed at a distance of 15cm from a convex lens of focal length 10cm. Calculate the distance and size of the image so formed. What will be the nature of image?

28.  Light enters from air to glass plate having refractive index 1.50. What is the speed of light if the speed of light in air is  m/s?

29.  What is dispersion? Which color of light deviates more on passing through a prism? When two prisms are placed together with one inverted and white light is passed, what will be the result? What are the conditions for the formation of rainbow? What are the values for the angle of incidence and angle of reflection for normal incidence?

30.  Which phenomenon does optic fiber work upon?

31.  An object is placed 20cm in front of mirrors M1 and M2 separately and image is found to be formed at a distance of 15cm in front of it in case of M1 and behind it in case of M2. Find the focal length and kind of mirror in each case.

 

 

 

Sunday, October 4, 2009

important Questions/classX/cbse

IMPORTANT QUESTIONS ------ PHYSICS (SCIENCE)

                                           CLASS    X

 

 

1.      A charge of 400 C flows through a conductor for 1.3 minutes and 20 seconds. Finds the magnitude of the current flowing through the conductor.

2.      A charge of 5000 C flows through an electric circuit in 2 hour and 30 minutes. Calculate the magnitude of the current flowing through the circuit.

3.      A dry cell can supply a charge of 300 C. If the current is drawn from the cell is 60 mA, find the time in which the cell completely discharges. 

4.      A battery con supply a charge of 2.5 105 C. If the current is drawn from the battery at a rate of 12.5 A, calculate the time in which the battery will be discharge.

5.      A dry cell can supply a charge of 800 c. If a continuous current of 8.0 mA is drawn, calculate the time in which cell will be discharged completely.

6.      A charge of 25 mA flows for 2 hour through a conductor. Calculate the number of electrons, which drift in the conductor. [Charge on one electron = 1.6 x 10 – 19 C]. 

7.      Calculate the total number of electrons flowing through a circuit in 20 minutes and 40 seconds, if a current of 40 mA flows through the circuit. [Charge on one electron = 1.6 x 10 -19 C)

8.      2.4 x 10 20 electrons flow through a circuit in 10 hours. Calculate the magnitude of the current. [Charge on one electron = 1.6 x 10–19 C].

9.      50 coulombs of charge is brought from infinity to a given point in an electric field when 62.5 j of work is done. What is the potential at that point?  

10.  What is the electric potential at a point in an electric field when 24 J of work is done in moving a charge of 84 C from infinity?

11.  A charge of 75 C is brought from infinity to a given point in an electric field; when the amount of work done is 12.5 J. Calculate the electric potential at that point.

12.  A charge of 2 C is moved in and electric field from infinity to two points A and B. If the work done in bringing the charge to point A is 12j and in bringing it to point B is 16 j. Calculate the potential difference between points A and B.

13.  Word of 25J and 30J is dome when 5 C charge is moved from infinity to a point A and then to a point B respectively. Calculate the potential difference between the points A and B.

14.  A charge of 25 C is moved from infinity to two points A and B in and electric field. The work done to do so up to A and B is 10 j and 12.5 j respectively. What is the potential difference between points A and B?

15.   The resistance of a wire of length 80 cm and of uniform area of cross-section 0.025 cm2,is found to be 1.50ohm. Calculate sp. Resistance of wire. 

16.  A wire of resistance 4.5ohm and length 150 cm, has area of cross-section of 0.04cm2. Calculate sp. Resistance of wire.

17.  What should be the length of nichrome wire of resistance 4.5 ohm, if the length of similar wire is 60 cm and resistance 2.5 ohm?

18.  Resistance of a conductor of length 75 cm is 3.25 ohm. Calculate the length of a similar conductor, whose resistance is 16.25 ohm.

19.  A nichrome wires has a resistance of 5 ohm. Find the resistance of another nichrome wire, Whose length is four times and area of cross-section three times the first wire. 

20.  A resistance wire made from German silver has a resistance of 4.25 ohm. Calculate the resistance of another wire, made from same material. Such that its length increases by three times. 

21.  A nichrome wire of length l and area of cross-section A/4 has a resistance R. Another nichrome wire of length 3l and area of cross-section A/2 has resistance of R1. Find the ratio of R1 and R2 .

22.  Write the nature of image formed by a plane mirror.

23.  What do you mean by conventional current flow?

24.  State Ohm's law. Give its mathematical form. Draw the graph showing the dependence of current on potential difference.

25.  When two resistors R1 and R2 connected in parallel to a source of energy, find the equivalent resistance.

26.  Why is the series arrangement not used for connecting domestic electric appliances in a circuit?

27.  Out of 60 W and 40 W lamps, which one has a higher electrical resistance when in use.

28.  Draw ray diagrams to represent the nature, position and relative size of the image formed by a convex lens for the object placed:  

         (a) at 2F1.   b) between F1 and the optical centre O of lens.

 

 

Thursday, May 14, 2009

HOW TO MAXIMIZE YOUR CHILD’S LEARNING ABILITY

Learning styles: What are they?

All of us learn through our senses AND through the senses of sight, hearing, touch, taste and feeling,  We use these to gather information. We interact with our environment using these senses. We look at things, hear things, touch them, taste them or feel them to try and understand them. This information that we get from our senses is then sent to the brain.

For example, we look at a lemon see that it is yellow and round, touch it and know that it is smooth, taste it and realize that it is sour. This information is then sent to the brain where it is processed. Then it is put away in the brain and stored till it is required. All this information that we gathered from our senses has helped us learn what a lemon is and what its properties are. When we
Then when we come across a lemon again, we know that it is a lemon, because we remember when we see it that it is round and yellow, smooth to the touch, has a citric smell and tastes sour.

However, each individual takes information in different ways from the environment. Some people use one sense; say for example, sight, more that they do hearing. That means they prefer to look at things and learn about them rather than listening to information about them. Each of us has a different way of learning and we have to try and discover this style of learning on our children to help them become more efficient and more effective learners.

Early in life, a baby rnakes sense of his environment by picking up things and putting them in his mouth. At his stage, his sense of touch and taste are the strongest means of understanding the world. These, taste and touch are the modalities, which are the stronger channels of learning.

As we grow older we rely less on our sense of taste. Other channels of learning become more acute and stronger, such as the sense of vision, hearing and movement. We begin to rely more on these to get information and to learn. Often One sense becomes stronger the others.

This is the sense (or senses) that we use to learn. For instance some of us may be better at remembering information when it is presented visually, and some of us may do better if we listen to information. This becomes our channel or modality of learning. This becomes our learning style.


How do you know the learning style of your child? What are the signs to look for? What will give you clues as to what modality your child prefers?


Three basic styles of learning

There are

  • visual,
  • auditory and
  • kinesthetic (movement)  

Children with a visual learning style, learn by looking at pictures, seeing things, watching demonstrations.

Children with an auditory style of learning, learn by listening to others and to themselves.

Children with a kinesthetic style of learning learn by doing, by touching and by using movement.

A child, whose style of learning is visual AND where the sense of sight is used, likes to read things. This is the child who recognizes spellings from the way they look. He has a good name for faces, but may not be able to remember names. This child will watch a speaker’s face, and / or try to take notes while listening to a teacher. This kind of learner watches people’s faces to gauge their emotions. A child with a strong visual mode of learning focuses on details and sees things as a whole. This child makes lists to remember what has to be done. He looks around and tries to remember details of what has been seen. When not involved in any activity, this child doodles / draws / sketches.

The visual learner prefers to write down telephone numbers and e-mail addresses to remember them, directions to a destination need to be written, or a diagrammatic map would help, just hearing these is not enough. Watching a movie or TV is an activity that the visual child prefers to hearing a story or listening to music. Imagery is mental in a visual learner; the child has a detailed, vivid imagination. In a new situation, a child with a visual mode of learning looks around and figures out what to do. Visual stimuli distract the child.

What helps your visual child to learn?

The visual learning child learns best when he is allowed to draw what he is learning. Encourage your child to make diagrams, note down points, highlight his work, colour code, important points, make notes in the margin underline important facts and make lists. Content material can be broken up into “chunks” so that the material is visually separated into segments. These techniques help the visual learner to learn better.

 When teaching spelling, the words can be broken up in syllables, with a gap between each syllable. Syllables can be colour coded. Encourage the child to make flow charts for science, maps for geography, and timelines for history, posters for literature and for poems. Encourage the child to make all study material as visual as possible. Remember that this visual child remembers and understands information better if he has read it. He learns by seeing it on paper.

The auditory child is the one who likes to learn by listening to things. Telephone numbers, e-mail addresses and verbal directions are understood and remembered quickly, This child enjoys plays and listening to dialogue. While working, he vocalizes what he is doing. When not doing anything in particular or when bored, the auditory learner will hum or sing softly to himself or talk to others. While spelling, this child uses phonic rules to sound out words and understands the sounds that go to make up a word. The child with a strong auditory modality of learning has a good memory for names, but cannot remember faces. This child repeats things to himself to remember them. Sounds distract the child. In a new situation, the child talks aloud and deliberates on the pros and cons. listening to music is a favored activity. Things are perceived as a whole, rather than in it are component parts. Auditory stimuli can distract this child.


What are some of the techniques that you can use to help your auditory child learn?

This child needs an auditory input while studying. So let him read aloud when studying. If he finds reading difficult, then you, the parent, read out aloud to your child. This child needs to be able to hear information to be able to understand it and to be able to remember it and to recall it when needed. This child needs to repeat things and to hear his voice when studying. The child memorizes by repeating out aloud. Multiplication tables and content material in various subjects will be best learned when they are put to music, chants, poems, etc. This technique has worked very successfully on children. Teach history through dialogue, through conversations between historical figures. Encourage this child to talk aloud the steps in a science experiment, to verbalize the steps in a multi-tiered mathematical problem. Sometimes having quiet background music helps this child to concentrate while studying. Ask the child, if this would help. Remember that the auditory child learns by hearing words spoken.

The child, who has a kinesthetic style of learning, is the child who is always moving and always doing things. This child takes things apart and puts them together. The kinesthetic child enjoys constructing things. He is interested in how things work. He is inquisitive as to how things are built and will take objects apart to see how they fit together. This child learns through manipulating materials.

 The child with a strong kinesthetic modality of learning fidgets while reading, is not a great reader and prefers stories which have action and where the action in the story comes at an early stage. Listening a long time to things, and activities that involve a lot of dialogue are not favoured activities of this child. When spelling, this child will write and rewrite words to see if the “feel” of the word is right. This child remembers things best when he does them himself.

The child with a strong kinesthetic style of learning fidgets and squirms when there is a period of inactivity. This child gestures while speaking and responds to new situations by touching, feeling, trying things out and manipulating things.
Teach spelling to this kinesthetic child by tracing and writing over words. If the words have a texture to them, for instance, if the words are made out of sandpaper, the learning will be stronger. This child will learn spelling better by writing words on his desk with a finger, writing words on parents’ backs, essentially by using movement and touch. Doing experiments in science, using manipulative and blocks for mathematics, measuring angles in geometry of objects such as tables and chairs will reinforce learning. Spelling can also be taught by having this child manipulate blocks that have letters written on them.

Other learning styles have to be kept in mind also. These refer to whether your child is an individual learner or a group learner. If your child is a group leaner, then your child prefers to study with at least one other child. For the group learner, the amalgamation of people and the interaction helps to increase learning. Socializing is important to your child. This child values the opinions of others.
Is your child an individual learner? If so, your child gets more work done when learning on his own. This child prefers to come up with solutions on his own.

Sunday, May 10, 2009

Gagne's Nine Events of Instruction: An Introduction

 

Just as Malcolm Knowles is widely regarded as the father of adult learning theory, Robert Gagne is considered to be the foremost researcher and contributor to the systematic approach to instructional design and training. Gagne and his followers are known as behaviorists, and their focus is on the outcomes - or behaviors - that result from training.

Gagne's Nine Events of Instruction

Gagne's book, The Conditions of Learning, first published in 1965, identified the mental conditions for learning. These were based on the information processing model of the mental events that occur when adults are presented with various stimuli. Gagne created a nine-step process called the events of instruction, which correlate to and address the conditions of learning. The figure below shows these instructional events in the left column and the associated mental processes in the right column.

Instructional Event

Internal Mental Process

1. Gain attention

Stimuli activates receptors

2. Inform learners of objectives

Creates level of expectation for learning

3. Stimulate recall of prior learning

Retrieval and activation of short-term memory

4. Present the content

Selective perception of content

5. Provide "learning guidance"

Semantic encoding for storage long-term memory

6. Elicit performance (practice)

Responds to questions to enhance encoding and verification

7. Provide feedback

Reinforcement and assessment of correct performance

8. Assess performance

Retrieval and reinforcement of content as final evaluation

9. Enhance retention and transfer to the job

Retrieval and generalization of learned skill to new situation

1.      Gain attention

In order for any learning to take place, you must first capture the attention of the student. A multimedia program that begins with an animated title screen sequence accompanied by sound effects or music startles the senses with auditory or visual stimuli. An even better way to capture students' attention is to start each lesson with a thought-provoking question or interesting fact. Curiosity motivates students to learn.

2.      Inform learners of objectives

Early in each lesson students should encounter a list of learning objectives. This initiates the internal process of expectancy and helps motivate the learner to complete the lesson. These objectives should form the basis for assessment and possible certification as well. Typically, learning objectives are presented in the form of "Upon completing this lesson you will be able to. . . ." The phrasing of the objectives themselves will be covered under Robert Mager's contributions later in this chapter.

3.      Stimulate recall of prior learning

Associating new information with prior knowledge can facilitate the learning process. It is easier for learners to encode and store information in long-term memory when there are links to personal experience and knowledge. A simple way to stimulate recall is to ask questions about previous experiences, an understanding of previous concepts, or a body of content.

4.      Present the content

This event of instruction is where the new content is actually presented to the learner. Content should be chunked and organized meaningfully, and typically is explained and then demonstrated. To appeal to different learning modalities, a variety of media should be used if possible, including text, graphics, audio narration, and video.

5.      Provide "learning guidance"

To help learners encode information for long-term storage, additional guidance should be provided along with the presentation of new content. Guidance strategies include the use of examples, non-examples, case studies, graphical representations, mnemonics, and analogies.

6.      Elicit performance (practice)

In this event of instruction, the learner is required to practice the new skill or behavior. Eliciting performance provides an opportunity for learners to confirm their correct understanding, and the repetition further increases the likelihood of retention.

7.      Provide feedback

As learners practice new behavior it is important to provide specific and immediate feedback of their performance. Unlike questions in a post-test, exercises within tutorials should be used for comprehension and encoding purposes, not for formal scoring. Additional guidance and answers provided at this stage are called formative feedback.

8.      Assess performance

Upon completing instructional modules, students should be given the opportunity to take (or be required to take) a post-test or final assessment. This assessment should be completed without the ability to receive additional coaching, feedback, or hints. Mastery of material, or certification, is typically granted after achieving a certain score or percent correct. A commonly accepted level of mastery is 80% to 90% correct.

9.      Enhance retention and transfer to the job

Determining whether or not the skills learned from a training program are ever applied back on the job often remains a mystery to training managers - and a source of consternation for senior executives. Effective training programs have a "performance" focus, incorporating design and media that facilitate retention and transfer to the job. The repetition of learned concepts is a tried and true means of aiding retention, although often disliked by students. (There was a reason for writing spelling words ten times as grade school student.) Creating electronic or online job-aids, references, templates, and wizards are other ways of aiding performance.

Applying Gagne's nine-step model to any training program is the single best way to ensure an effective learning program. A multimedia program that is filled with glitz or that provides unlimited access to Web-based documents is no substitute for sound instructional design. While those types of programs might entertain or be valuable as references, they will not maximize the effectiveness of information processing - and learning will not occur.

How to Apply Gagne's Events of Instruction in e-Learning

As an example of how to apply Gagne's events of instruction to an actual training program, let's look at a high-level treatment for a fictitious software training program. We'll assume that we need to develop a CD-ROM tutorial to teach sales representatives how to use a new lead-tracking system called STAR, which runs on their laptop computers.

1. Gain attention

The program starts with an engaging opening sequence. A space theme is used to play off the new software product's name, STAR. Inspirational music accompanies the opening sequence, which might consist of a shooting star or animated logo. When students access the first lesson, the vice president of sales appears on the screen in a video clip and introduces the course. She explains how important it is to stay on the cutting edge of technology and how the training program will teach them to use the new STAR system. She also emphasizes the benefits of the STAR system, which include reducing the amount of time representatives need to spend on paperwork.

2. Inform learners of objectives

The VP of sales presents students with the following learning objectives immediately after the introduction.

Upon completing this lesson you will be able to:

·         List the benefits of the new STAR system.

·         Start and exit the program.

·         Generate lead-tracking reports by date, geography, and source.

  • Print paper copies of all reports.

3. Stimulate recall of prior learning

Students are called upon to use their prior knowledge of other software applications to understand the basic functionality of the STAR system. They are asked to think about how they start, close, and print from other programs such as their word processor, and it is explained that the STAR system works similarly. Representatives are asked to reflect on the process of the old lead-tracking system and compare it to the process of the new electronic one.

4. Present the content

Using screen images captured from the live application software and audio narration, the training program describes the basic features of the STAR system. After the description, a simple demonstration is performed.

5. Provide "learning guidance"

With each STAR feature, students are shown a variety of ways to access it - using short-cut keys on the keyboard, drop-down menus, and button bars. Complex sequences are chunked into short, step-by-step lists for easier storage in long-term memory.

6. Elicit performance (practice)

After each function is demonstrated, students are asked to practice with realistic, controlled simulations. For example, students might be asked to "Generate a report that shows all active leads in the state of New Jersey." Students are required to use the mouse to click on the correct on-screen buttons and options to generate the report.

7. Provide feedback

During the simulations, students are given guidance as needed. If they are performing operations correctly, the simulated STAR system behaves just as the live application would. If the student makes a mistake, the tutorial immediately responds with an audible cue, and a pop-up window explains and reinforces the correct operation.

8. Assess performance

After all lessons are completed, students are required to take a post-test. Mastery is achieved with an 80% or better score, and once obtained, the training program displays a completion certificate, which can be printed. The assessment questions are directly tied to the learning objectives displayed in the lessons.

9. Enhance retention and transfer to the job

While the STAR system is relatively easy to use, additional steps are taken to ensure successful implementation and widespread use among the sales force. These features include online help and "wizards", which are step-by-step instructions on completing complex tasks. Additionally, the training program is equipped with a content map, an index of topics, and a search function. These enable students to use the training as a just-in-time support tool in the future. Finally, a one-page, laminated quick reference card is packaged with the training CD-ROM for further reinforcement of the learning s

 

Review Questions

1.       Sketch a graph showing the variation of resistivity of carbon with temperature.

2.       Two copper spheres of same radii , one hollow and another solid are charged to same potential. Which of the two will have more  charge.

3.       An electric dipole of dipole moment   50X10-6 C m is enclosed by a  surface. What is the net flux  coming out of the surface.

4.       Explain why two electric field lines cannot cross each other at any point.

5.       Sketch the equipotential surface for a system of dipole.  

6.       Determine the current through a carbon resistor having colour rings red,green and red respectively when connected to 10 V battery.

7.       Obtain the relation between drift velocity and relaxation time. Also show that current density is directly proportional to relaxation time.

8.       By using Gauss’s theorem, derive an expression for electric field due to a infinitely long straight uniformly charged conductor.

9.       A battery of emf 10V and internal resistance 2 Ω is connected to a resistor. If the current in the circuit is 0.5 A, what is the resistance of the resistor? What is the terminal voltage of the battery when the circuit is closed.

10.   (i)  Define the term  electric dipole moment. Is it scalar or vector? Give its SI unit.             

               (ii) Deduce an expression for electric field at a point on equatorial plane of an dipole of length 2a.  

                                                                                OR

(i) Define capacitance. Give its SI unit.

(ii) Obtain an expression for the capacitance of a parallel plate capacitor when a dielectric slab of thickness “t” is introduces between the plates of capacitor.