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ISC Class 12 Physics Solved Question Paper 2004

Short Answer Type

21. An ionized helium particle (+2e) is situated at the origin (0, 0). How much work is done in taking an electron from x = 3 cm to x = 6 cm?

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22. Given that the resistance of the voltmeter is 400 Ω, find the voltmeter’s reading.

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23. Show that the radius of a charged particle entering perpendicularly in a magnetic field is directly proportional to its momentum.

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24. Find the inductance of a choke coil needed to run an arc lamp, with an a.c. source of 100 V supply at 50 Hz. The arc runs at 10 amp. current and has an effective resistance of 4 Ω.

Here,

V = 100 V, f = 50 Hz, I = 10 amp., R = 4 Ω, L = ?, X_L = ?

V = IZ

Impedence, Z,

$straight V over straight I space equals space 100 over 10 space equals space 10 capital omega space equals space square root of R squared space plus space X subscript L squared end root left parenthesis 10 right parenthesis squared space equals space 4 squared space plus space X subscript L squared square root of 100 space minus space 16 end root space equals space X subscript L square root of 84 space equals space X subscript L space X subscript L italic space italic equals italic space omega subscript L X subscript L italic space italic equals italic space italic 2 italic space pi f L italic space fraction numerator X subscript L over denominator italic 2 pi italic space italic left parenthesis italic 50 italic right parenthesis end fraction italic space italic equals italic space L italic space italic equals italic space fraction numerator square root of italic 84 over denominator italic 100 italic space pi end fraction italic space$

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25. State any five electromagnetic waves and arrange them in the increasing order of their penetrating power.

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26.

What type of wave front is produced by:

(i) Point source of light (ii) Line source of light

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27. Define dispersive power. The dispersive power of an achromatic doublet is 2/3 and the combined focal length of the combination is 30 cm. Find the focal length of each lens stating its nature.

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28.

Calculate the focal length of a concave lens with the help of the above ray diagram. Focal length of convex lens is 20 cm.

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29.

A fish is located at a distance of 10 cm from the wall of a fish pond. The thickness of the glass wall is 2 cm. Find the apparent position of the fish. (Given

_aμ_g = 3/2 and _aμ_w= 4/3)

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