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The Global Classroom carries the unique GEMS “Dynamic” materials and assessments of Dr Sunita Gandhi, Ph.D. Cambridge University, UK. These have been tested and tried in three countries, Iceland, India and the UK, and perfected with a three year trial with over 40,000 children in India participating.

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ALL Past Questions TOPIC WISE For The Last 10-12 years

Topic 3: LIGHT Sub Topic 2: Refraction through Lenses.Optical Camera and Human Eye

1.	The ray diagram given below illustrates the experimental set up for the determination of the focal length of a converging lens using a plane mirror.	Marks [3]

i	State the magnification of the image formed.
ii	Write two characteristics of the image formed.
iii	What is the name given to the distance between the object and optical centre of the lens in the above diagram?
	Choice in 2005

2.	The diagram given alongside shows an object O and its image I. Copy the diagram and draw suitable rays to locate the lens and its focus.	Marks [4]

	Name the type of lens in this case.
	Choice in 2004

3.	A ray of light, after refraction through a concave lens, emerges parallel to the principal axis. Draw a ray diagram to show the incident ray and its corresponding emergent ray.	Marks [2]
	Compulsory in 2003

4.	State the characteristics of the image of an extended source, formed by a concave lens.	Marks [3]
	Compulsory in 2003

5.	State two similarities between a photographic camera and the human eye.	Marks [2]
	Compulsory in 2002

6.	An erect, diminished and virtual image is formed when an object is placed between the optical centre and principal focus of a lens.	Marks [4]
i	Name the type of lens, which forms the above image.
ii	Draw a ray diagram to show the formation of the image with the above characteristics.
	Compulsory in 2002

7.	In an optical camera state:	Marks [4]
i	The name of the lens used.
ii	What is meant by f-number?
iii	Two Characteristics of the image formed by the lens.
	Compulsory in 2001

8.	Name any two essential parts of a single lens photographic camera.	Marks [2]
	Choice in 2002

9.	Draw a ray diagram to illustrate the action of a convergent lens as reading glasses or a magnifying glass.	Marks [4]
	Choice in 2000

Topics Covered
1.	Force, Work, Energy And Machines	5.	Electricity And Magnetism
a	Force And Second Law Of Motion	a	Ohm's Law And Resistance
b	Work, Power And Energy	b	Electric Circuit
c	Levers And Inclined Plane	c	Electric Power
d	Pulleys	d	Electromagnetism
2.	Heat	e	Electromagnetic Induction
a	Specific Heat And Its Determination	6.	Modern Physics
b	Change Of State And Latent Heat	a	Thermionic Emission And Cathode Ray Tube
3.	Light	b	Radioactivity And Safety Precautions
a	Refraction At A Plane Surface And Total Internal Reflection	c	Nuclear Energy
b	Refraction Through Lenses, Optical Camera And Human Eye
c	Refraction Through Prism
d	Spectrum And Colours
4.	Sound
a	Reflection Of Sound
b	Wave Motion
c	Forced Vibrations And Resonance
d	Loudness, Pitch And Quality Of Sound

Advantages
1.	Topicwise Presentation Of All Past Questions Allows Topicwise Revision. Past Questions Are The Most Important Questions You Must Solve First.
2.	Frequency analysis shows types of past questions with marks, year reference and whether choice or compulsory, short or long.
3.	Eliminates questions on topics not part of a forthcoming Board Exam.
4.	Adds model questions for new topics in a forthcoming Board Exam.
5.	Data is presented from the most recent to earlier years, covering 10-12 years.
6.	Perfect for making strategy and for the prioritization of study objectives.

Solutions To All Past Questions

Topic 3: Light Sub Topic 2: Refraction Through Lenses. Optical Camera And Human Eye

Question

Solution

Formulae/Concepts Used

Tips

Draw A Ray Diagram To Illustrate The Action Of Convergent Lens As A Reading Glass Or A Magnifying Glass.

[2]
Compulsory in 2002

A Convex Lens Produces Erect And Magnified Image Of An Object When The Object Is Placed Within The Focus Of The Lens.

The Ray Diagram Above Illustrates The Action Of A Convex Lens As A Reading Glass Or A Magnifying Glass.

i	Object Should Be Placed Within The Focus Of A Convex Lens.
ii	Ray Of Light Passes Through The Optical Centre Undeviated.
iii	A Ray-Parallel To The Principal Axis After Refraction Passes Throughfocus.

i	A Pair Of Rays Starting From The Head Of The Object One Parallel To The Principal Axis And The Other Through The Optical Centre Should Be Taken.
ii	Rays Produced Backward Should Be Drawn With Broken Line.
iii	Virtual Image Should Be Drawn With Broken Line.
iv	Arrow Heads Must Be Put On The Rays.

Advantages Solutions To All Past Questions
•	They Allow Self Check.
•	They Guide As To How And How Much To Write In The Board Exam.
•	Learn Backwards From Answers.
•	Learn How To Answer In A Board Exam.
•	Tips And Formulae To Memorize.
•	Last Minute Help: Gain Marks Even While You Sit And Read In Bed!

Revision Notes
•	Revision Notes On What Has Already Come In The Last 10-12 Years Are Helpful Throughout The Year, Just Before Examinations, Or Even The Night Before Exam. They Provide A Quick Synopsis Of Solutions And Tips On Each Topic.

Topic: Sound

Topic

No. of Questions
(in the last 10 year papers)

Questions with Solutions

Sound

Sub Topic III:

Forced Vibrations And Resonance

7 Questions

Marks Of These Questions Range From 2 To 4. These Questions Have Come Both In The Compulsory And Choice Section.

2004/1998, 2003, 2002 (Solved), 2001, 2000, 1999 And 1996.


Question (2002), 4 Marks, Choice
A Vibrating Tuning Fork Is Placed Over The Mouth Of A Burette Filled With Water. The Tap Is Opened And The Water Level Gradually Falls. It Is Observed That The Sound Becomes The Loudest For A Particular Length Of Air Column.
•	What Is The Name Of The Phenomenon Taking Place When This Happens?
•	Why Does The Sound Become Loudest?
•	Name The Phenomenon Taking Place When Sound Is Produced For Another Length Of Air Column And Is Not The Loudest.
Solutions
•	The Name Of The Phenomenon Is Resonance.
•	During Resonance, The Frequency Of The Vibrating Tuning Fork And The Frequency Of The Air Column Becomes Equal And Hence The Amplitude Of The Sound Wave Increases To The Maximum, So The Sound Becomes Loudest.
•	This Will Be A Phenomenon Of Resonance Corresponding To The First Harmonic Mode Of Vibration Of Air Column.

Guidelines/Formulae

Tips

[We Open The Tap To Take Out The Water. As The Water Level Falls The Length Of The Air Column Increases]

This Is A Case Of Resonance In Air Column. When The Natural Frequency Of The Air Column Is Matching With The Frequency Of The Vibration Of The Tuning Fork Then We Hear The Loudest Sound.

Different Heights Of Air Columns Have Different Natural Frequencies.

Other Concepts:
(I)Free Vibration:– The Vibration Of Body With Its Natural Frequency (In The Absence Of Any Dissipative Force) Is Called Free Vibration.
(Ii)Damped Vibration:– The Vibration Of A Body With Decreasing Amplitude Is Called Damped Vibration.
(Iii)Forced Vibration:– Takes Place Under The Influence Of An External Periodic Force.
(iv) Resonance Is A Special Case Of Forced Vibration; When The Frequency Of The Applied Periodic Force Is Equal To The Natural Frequency Of The Body.

Resonance Will Be For A Particular Height Of Air Column

Resonance Occurs When N = F Or 2f Or 3f..............
It Is Loudest When N = F. Normally For Another Length Of Air Column Which Will Be Nearly 3 Times Of The First Length We Can Hear A Loud Sound.

Tick:How Do You Find This Topic?

Advantages
•	No Need To Make Separate Extensive Revision Notes.
•	Especially Excellent For Last Minute Revision.
•	Use Your Short-Term Memory To Boost Results By Reviewing These Notes The Night Before Exam, When Your Mind Is The Keenest!

Prioritize Using Smart Study Plan Interpretation
•	On Topic 7: Forced Vibrations And Resonance, There Have Been Nine Past Questions In The Last 12 Years.
•	They Came In The Years 2006, 2004, 2003, 2002, 2001, 2000, 1999, 1998 And 1996.
•	Whether They Were Compulsory Or Choice Questions Is Indicated By C Or NC.
•	For Example, The 2006 Question Was Worth Three Marks And Was Not Compulsory.
•	Suggested Time To Attempt All These 9 Questions On Your Own Is 27 Minutes.

Frequency Analysis And Planning Chart

Advantages
•	Find Out Which Past Questions Were Difficult For You By Filling Out Each Circle According To How Difficult You Found A Question.
•	Study According To Your Personal Strengths.
•	Save Time By Planning Better.
•	Revise These Questions For A Second Time To Maximize Marks.
•	Have A Thorough Knowledge Of What Has Already Come In The Last 13 Years On Each Topic.

Remember

Going Over Past Questions Gives You More Confidence. Solutions To Every Past Question As Per Board Guidelines Ensure You Gain Every Possible Mark.

These Are The Most Important Hours You Will Spend Towards Preparation Of Your Board Exam.

Extras
•	How To Work Smart: 10 Keys To Success By Dr Sunita Gandhi.
•	Nutritional Guidelines By Dr Amitabh Pandit, A Well Known Naturopath.
•	Cd–Includes Ten Keys Of Dr Gandhi As Explained By The Students Of City Montessori School (Cms), Lucknow, Up And Testimonies of Students Who Have Used The Sure Success Series.

Please Note
•	Questions And Topics Not Relevant To A Future Board Exam Are Not Included.
•	New Model Questions Are Added Whenever A New Topic Has Been Included By The Council For A Forthcoming Board Exam.

Other Subjects
	Class X		Class XII
•	English Language	•	English Language
•	Hindi	•	Hindi
•	History & Civics	•	Accounts
•	Geography	•	Commerce
•	Commercial Studies	•	Economics
•	Computer Applications	•	Physics
•	Physics	•	Chemistry
•	Chemistry	•	Biology
•	Biology	•	Mathematics
•	Mathematics
•	Economics & Economic Applications

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