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.

ISC Class 12 Physics Solved Question Paper 2008

Short Answer Type

21. Obtain an expression for the electric potential at a point which is at a distance r from the point charge Q.

408 Views

22. Find the equivalent capacitance of the following circuit between the junctions A and B; given C₁ = C₂ = C₃ = C₄= 10μF and C₅ = 5,μF.

In the given circuit

C_l = C₂ = C₃ = C₄ = 10 μf

Therefore,

$straight C subscript 1 over straight C subscript 2 space equals space C subscript 3 over C subscript 4$
Thus given circuit is a balanced Wheat-Stone Bridge. So the P.d. across the ends of C₅ is zero. Capacitance C₅ is ineffective.

So equivalent circuit can be made as -Capacitances C₁and C₂ are in series.

So equivalent capacitance C_S is,

$1 over straight C subscript straight S space equals space 1 over C subscript 1 space plus space 1 over C subscript 2 space space space space space space space space equals space 1 over 10 space plus space 1 over 10 1 over C subscript s space equals space 2 over 10 C subscript S space equals space 5 space mu F S i m i l a r l y comma space C subscript 3 space end subscript a n d space C subscript 4 space a r e space i n space s e r i e s. space S o space e q u i v a l e n t space c a p a c i a t n c e space C subscript s space i s C subscript s apostrophe space equals space 5 space mu F space C subscript s space a n d space C subscript s apostrophe space a r e space i n space p a r a l l e l. space H e n c e space e q u i v a l e n t space c a p a c i t a n c e space i s comma space C space equals space C subscript 6 space space plus space C subscript s apostrophe space space space equals space 5 space mu F space plus space 5 mu F space space space equals space 10 space mu F$

1461 Views

23. A galvanometer with a coil of resistance 100 Cl and a scale having 100 divisions has a current sensitivity of 25 μ A / division.'How will you convert it into an ammeter of range 0 to 5A ?

377 Views

24. The emf ‘E’ of a thermocouple varies with the temperature θ (in degree C) of the hot junction (cold junction at 0°C) as E = 15 q 0.05 q^2.
Determine the neutral temperature.

432 Views

25. Using either deflection magnetometer or vibration magnetometer, explain how will you compare magnetic moments of two given bar magnets.

1512 Views

26. Two very long straight parallel conductors carrying currents I₁ and I₂ in vacuum are separated by a distance ‘a’. Write an expression for the force experienced per unit length by one wire due to the current flowing through the other wire and hence define the fundamental unit of current, i.e., an ampere.

489 Views

27. When the primary of a transformer is connected to a 120 V AC mains, the current in the primary is 18.5 mA. Find the voltage across the secondary when it delivers 1.5 mA current through it, assuming the transformer to be an ideal one. State any one type of energy loss in a transformer.

222 Views

28. Draw a simple ray diagram showing the formation of a primary rainbow.

368 Views

29. Using Huygen’s Principle, prove the laws of refraction of light.

1748 Views

30. The figure below shows the positions of the first bright fringes B₁, and B₂ on either side of the central bright fringe O in Young’s double slit experiment. Find the wavelength of monochromatic light used.