## Thursday, December 16, 2010

### SET OF MUST PRACTICE QUESTIONS FOR CBSE PHYSICS CLASS XII (AISSCE PHYSICS 2011)

Hello Dear Students, If you were searching for a set of questions which you cannot afford to leave while preparing for AISSCE 2011 Physics Exam, Here it is. Please practice them carefully. If you have any doubt in answering any of these questions, please feel free to ask at www.askphysics.com The content is being updated by adding more questions daily. So please come back soon for more

ELECTROSTATICS

1. State Coulomb's law and express it in vector form

2. Derive an expression for the electric field due to a dipole at a point on its

1. axial position and

2. on the equatorial position.

3. State Gauss theorem of electrostatics and use it to find the electric field at a point due to

1. A point charge

2. A line of charge

3. A plane sheet of charge

4. A sphere of charge

4. Derive Coulomb's law from Gauss theorem

5. Derive an expression for the torques on a dipole in a uniform electric field

6. Derive an expression for the work done in rotating a dipole in a uniform electric field

7. Derive an expression for t6he potential energy of a dipole in a unifor electric field

8. Derive an expression for the potential energy of a system of point charges

9. Describe the principle of a parallel plate capacitor

10. Derive an expression for the capacitance of a parallel plate capacitor.

11. Derive an expression for the effective capacitance when capacitors are connected in (a) parallel (b) series

12. Derive an expression for the energy stored in a parallel plate capacitor

13. Derive an expression for the electric potential due to (a) a point charge (b) a system of point charges

14. Describe the principle construction and working of Van de Graff generator

CURRENT ELECTRICITY

1. State Ohm's law

2. Define drift velocity and derive an expression for it.

3. Derive the relation I = nAev

4. Deduce Ohm's law

5. Explain why the resistance of a conductor increases with increase in temperature.

6. Derive expression for the effective resistance when three resistors are connected in (a) series (b) parallel

7. State Kirchhoff laws

8. What is a Wheatstone's bridge? State its principle and deduce it using Kirchhoff laws.

9. Explain how a metre bridge is used to determine the resistance of a given wire.

10. State and explain the Principle of a potentiometer and describe the experiment to determine the internal resistance of a primary cell using potentiometer.

11. Describe how a potentiometer is used to compare the emfs of two primary cells.

To be updated soon

MAGNETIC EFFECTS OF CURRENT

1. State Biot Savart law and apply it to determine the strength of magnetic field at a point on the axis of a circular coil carrying current

2. State Ampere's circuital law and apply it to find the magnetic field inside a solenoid and a toroid.

3. Describe the principle construction and working of a cyclotron. Why a cyclotron cannot be used to accelerate electrons

4. Derive an expression for cyclotron frequency

5. Explain the principle construction and working of a moving coil galvanometer.

6. Define the terms figure of merit and sensitivity of a galvanometer.

7. Describe how will you convert a galvanometer into (a) ammeter (b) voltmeter

To be updated soon

ELECTROMAGNETIC INDUCTION AND AC

ELECTROMAGNETIC WAVES

1. Describe Hertz experiment to produce em waves

2. Write the properties of em waves

3. What is em spectrum? Write any 5 constituents of em spectrum in the order of increasing wavelength. Write two uses of each

4. Write Maxwell's equations.

5. Discuss the inconsistency of Ampere's circuital law and how it is removed in Ampere - Maxwell law.

6. What is displacement current?

7. Explain how em waves are produced?

8. Describe the transverse nature of em waves. (Show that em waves are transverse in nature)

OPTICS

DUAL NATURE OF MATTER AND RADIATIONS

ATOMS AND NUCLEI

ELECTRONIC DEVICES

COMMUNICATION SYSTEMS

One mark questions

1. What is the meant by the term attenuation ?

2. Why ground wave transmission is restricted to 1500 kHz?

3. Define critical frequency in sky wave propagation.

4. What type of modulation is required in TV transmission?

5. Why AM radio reception is affected by electrical disturbances while FM radio reception is not?

6. What should be the length of a dipole antenna for a carrier wave of frequency 3 x 108 Hz

7. Draw a block diagram showing the basic communication system.

8. What is the range of frequencies used for FM radio transmission?

Two marks Questions

1. Distinguish analog and digital transmission

2. Write the functions of transducer and repeater in Communication systems. 3. Distinguish amplitude modulation and frequency modulation.

4. Draw a block diagram showing a simple amplitude modulator

5. Explain how a message signal is extracted from Amplitude Modulated signal.

6. Distinguish Sky wave propagation and Space wave propagation.

7. Name the different layers of earth’s atmosphere.

8. Mention two ways in which the range of transmission can be increased.

9. Explain the term modulation index and describe its significance.

10. List four devices used for communication each of which differ from other in the mode of communication.

Three marks questions

1. Explain the need for modulation

2. Derive an expression for the range of transmission from an antenna of height h.

3. Describe the demodulation of AM wave using waveforms and circuit diagrams.

### Electronic Regulator

how an electronic circuit works as a regulator?

In an ordinary regulator, the current in the circuit is controlled by increasing or decreasing the resistance.

But in an electronic regulator, the control is taken over by electronic circuits. There are different forms of electronic regulators available. Some use transistors, some use operational amplifiers etc. In electronic regulators, the voltage output is changes by electronic means (as in a transistor amplifier). Visit http://en.wikipedia.org/wiki/Voltage_regulator#Electronic_voltage_regulators for more details

## Wednesday, December 8, 2010

### 320 Job Offers To DTU Students; Highest Salary Is Rs 10.49 Lakh

Placements at the Delhi Technological University (DTU), formerly known as the Delhi College of Engineering (DCE), are rocking this year as 54 companies who visited the campus made 320 job offers to its students. Microsoft has offered the highest pay package so far at Rs 10.49 lakh per annum. The number of recruiters is expected to increase by 30% for students of the 2010-11 batch.

### University Of Pune Wins \$35000 Australian Leadership Award Fellowship For Inclusive Education System

University of Pune's Department of Education and extension won the Australian leadership award fellowship worth \$35,000 (Rs 15.30 lakh), given by the Australian government. The award was initiated by the Monash University, Melbourne and is given for developing an inclusive education system that allows differently-abled students to attend regular classroom sessions. Other universities who won the fellowship include University of Dhaka, Beijing Union University and East China Normal University, China.

### Ratan Tata To Deliver A Rare Lecture on Strategic Management at IIMA

In a very rare gesture, Mr. Ratan Tata - Chairman of Tata Sons, has agreed to deliver a lecture on strategic Management at the International Conference organized by the Indian Institute of Management-Ahmedabad (IIMA) from December 15 to December 17 through video-conferencing. Other eminent personalities participating in the event through video-conferencing include global strategist Prof Pankaj Ghemawat and Nobel Laureate and founder of Grameen Bank Dr Muhammad Yunus.

### LPU, TIE and Punjab Info-Tech To Establish Incubation Center To Promote Entrepreneurship

Lovely Professional University and Punjab Info-Tech have signed up a Memorandum of Understanding to promote innovative entrepreneurship projects. Punjab Technical University (PTU), Jalandhar and LPU are in talks with Taiwanese delegates to establish Incubation Centers for it. The Indus Entrepreneurs (TIE) is also a partner in the project.

### AIT and Australian Varsity Will Soon Offer Joint Programmes In Nursing And Biomedical Sciences

Ansal Institute of Technology (AIT) and Edith Cowan University (ECU) in Australia have signed a Memorandum of Understanding (MoU) to encompass development of programmes and services in areas such as engineering, business communication, information technology, hotel management, and nursing and health education. They will also conduct collaborative research projects and exchange programs for students and staff members. AIT and ECU will soon offer joint programmes in India in Nursing and Biomedical Sciences.

## Thursday, December 2, 2010

### KVPY Interview – How to Prepare?

First of all, hearty congratulations to all those who qualified for the KVPY (Kishore Vygyanik Protsahan Yojna) interview.

##### Results of the Aptitude Test held on 31st October 2010

Found your name in the selection list?

The next step is interview. The weightage for interview is 50%

As KVPY is installed to promote research, your research aptitude and observational skills will help you to excel in the interview.

## Wednesday, December 1, 2010

### TERI To Set Up Centre Of Excellence In Nano Biotechnology With Australian University

The Energy and Resources Institute (TERI), India has signed a Memorandum of Understanding (MoU) with the Deakin University, Australia to set up the TERI-Deakin Nano Biotechnology Research Centre. The initiative aims to augment research and collaboration between industry and academia and offer effective and efficient biotechnological solutions for a sustainable future.

### Online Examination System For Army Recruitment To Be Launched From Jan 2011

Brigadier Pankaj Sinha, Deputy Director General of the Chennai’s Army Recruitment Zone, announced on Friday that a new online examination system for recruitment in army will be launched from January 2011. He added that 33000 candidates from the six coastal districts of Andhra Pradesh and the Union Territory of Yanam in Puducherry turned up for the recruitment drive organized there recently, making it a great success.

### INSEAD Launches Executive Education Program For Senior Indian Executives

INSEAD, one of the world’s largest graduate international business schools, and recently ranked No. 1 in Businessweek’s 2010 ranking of international business schools, is deepening its reach in Asia by launching a specially designed one year leadership programme in India. ‘INSEAD Leadership Programme for Senior Indian Executives’ [ILPSIE] begins from the next academic year in August 2011.

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### Now have more fun at www.askphysics.com

Ask Physics is now more dynamic and Social Networking enabled. Members enjoy a lot of facilities like face book integration, making friends online, sending private messages, forums and groups and many more. Visit ask physics to find out the new additions and facilities.

Though anyone can ask a question and get the answers by email, joining the site as a member adds to the fun. Members can post questions directly to forums, join groups of their interest, like or unlike the posts and activities by other members, add members as friends, send messages to friends and a lot more are in the making.

Teachers can also join the site and start posting answers to the questions as well as taking part in online discussions at forums.

Future Plans

Ask Physics is planning to start a separate section for Physics Classroom Videos.