Monthly Archive: February 2011

Feb 28

Be wise while selecting Five marks questions !

Some Guidelines For students appearing for class XII Physics Board Exams.

Answering 5 marks questions

CBSE gives two options for each five marks questions.

You have to be wise while selecting the question for answering. In some cases, one option will carry a “describe the principle construction and working” type and the other may be a combination

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Feb 28

Derive an expression for current in terms of drift velocity. (Derive I = nAev)

(This is being posted as per request from students)

Consider a conductor of length l and area of cross section A. Let the number of free electrons per unit volume be n. When a pd V is applied, let the

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Feb 27

AISSCE Physics 2011 – Sure Shot Questions (Some Suggestions)

Do you know? There are almost always some questions asked from these portions.

Photoelectric effect (Please learn the full portion) Logic gates (please learn full as per syllabus) LCR

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Feb 26

Transistor as a Switch

transistor_switch

(This is one of the Expected Question for AISSCE Physics 2011)

Explain the action of transistor as a switch.

To answer this question (with proper understanding) you should have an idea of the three regions

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Feb 26

Beats Animation

super4

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Feb 23

Collection of CBSE Class 12 Previous Question Papers

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Feb 22

Class XII Physics SOME QUESTIONS FROM CBSE 2004 Board Question Paper

1

Physics 2004 Set 1

  1. Why is shortwave band used for long distance radio broadcast?
  2. Two metals A and B have work functions 2 eV and 5 eV respectively. Which metal has lower threshold wavelength?
  3. Draw the voltage-current characteristic of a zener diode.
  4. A solenoid with an iron core and a bulb is connected to a d.c. source. How does the brightness of the bulb change when the iron core is removed from the solenoid?
  5. Peak value of e.m.f of an a.c. source is E0. What is its r.m.s value?
  6. An electric dipole of length 4 cm, when placed with its axis making an angle of 60° with a uniform electric field, experiences a torque of Nm. Calculate the (i) magnitude of the electric field (ii) potential energy of the dipole, if the dipole has charges of ± 8 nC.
  7. Explain how the resistivity of a conductor depends upon (i) number density ‘n’ of free electrons, and (ii) relaxation time ‘λ’.
  8. Two long parallel straight wires X and Y separated by a distance of 5 cm in air carry currents of 10 A and 5 A respectively in opposite directions. Calculate the magnitude and direction of the force on a 20 cm length of the wire Y.

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