Subject

Physics

Class

ICSE Class 12

Pre Boards

Practice to excel and get familiar with the paper pattern and the type of questions. Check you answers with answer keys provided.

Sample Papers

Download the PDF Sample Papers Free for off line practice and view the Solutions online.
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 Multiple Choice QuestionsShort Answer Type

31. Draw the circuit diagram for a common emitter NPN transistor, stating the input and output wave form. 
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32. What are logic gates. Give the electronic circuit for the realization of AND GATE. [Diode combination showing input and output with biasing].
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 Multiple Choice QuestionsLong Answer Type

33. State and prove Tangent law. 
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34. A magnet makes 12 oscillations per minute in the earth’s magnetic field alone and 15 oscillations per minute when a short magnet with its axis horizontal and its south pole pointing north is placed with its center 20 cm directly above the oscillating magnet. Find the magnetic moment of the magnet. (Given : BH= 0.36 x 10-4 Tesla).


open parentheses straight t subscript 1 over straight t subscript 2 close parentheses squared space equals space fraction numerator B subscript H space plus space B over denominator B subscript H end fraction

rightwards double arrow space B space equals space B subscript H space open parentheses t subscript 1 over t subscript 2 close parentheses squared space space minus space 1
rightwards double arrow space open parentheses t subscript 1 over t subscript 2 close parentheses squared space minus space 1 space equals space B over B subscript H

where,

tl = 15 oscillation/sec and t2 = 12 oscillation/sec and

B
H = 0.36 x 10-4 T

rightwards double arrow space open parentheses 15 over 12 close parentheses squared space minus space 1 space equals space B over B subscript H

rightwards double arrow space fraction numerator 225 space minus space 144 over denominator 144 end fraction space equals space fraction numerator B over denominator 0.36 space x space 10 to the power of negative 4 end exponent end fraction

rightwards double arrow space B space equals space fraction numerator 81 space x space 0.36 space x space 10 to the power of negative 4 end exponent over denominator 144 end fraction

rightwards double arrow space B space equals space 2.025 space x space 10 to the power of negative 5 end exponent

rightwards double arrow space B space equals space fraction numerator mu subscript o over denominator 4 pi end fraction. space fraction numerator 2 M apostrophe over denominator d cubed end fraction space

space space space space space M apostrophe space equals space fraction numerator 2 pi over denominator mu subscript o end fraction. space B d cubed space

O n space p u t t i n g space t h e space v a l u e s comma space

space space space space space M apostrophe space equals space 20.25 space
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35. What is meant by back e.m.f. of a motor ? The back e.m.f. of a motor delivering 5 kW is 100 V, while operating on 110 V supply. Find the current and resistance of the motor. 
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36. What are the conditions necessary for sustained interference?

In Young’s double slit experiment the distance of the 4th Bright fringe from the central zero is 1.5 mm. The distance between the slits and the screen is 1.5 m and the distance between the slits is 2 mm. Find the wavelength of light used.
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37. State one experiment to determine the velocity of light. Draw necessary ray diagram and derive the formula used.
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38.

Derive the formula for angular magnification of a compound microscope, when the final image is formed at least distance of distinct vision. Draw the required ray diagram. 

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39.

Give the expression for the velocity of electron in the first orbit of Hydrogen atom and for the radius in the ground state of Hydrogen atom.

Hence derive the expression for the kinetic energy of the electron.

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40.

In Millikan’s oil drop experiment, a charged oil drop of density 880 kg/m3 is held stationary between two parallel plates 6.0 mm apart at a potential difference of 1000 volts. When electric field E is switched off, the oil drop was observed to fall a distance of 2.0 mm in 35.7 seconds.    [4]

(i) Find the radius of oil drop.

Given :

η for air = 1.8 x 10-5 poise

Density of air = 1.29 kg/m3

Use g = 9.81 m/s2

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