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 2007

Short Answer Type

41. Calculate the equivalent energy in MeV of a unified atomic mass unit.

We know that,

1 amu = 1.660565 x 10^-27kg

Energy equivalent to this mass, E = mc²

E = (1.660565 x 10-27) x (2.998 x 10⁸)²

E = 1.4925 x 10^-10J

$straight E space equals space fraction numerator 1.4925 space straight x space 10 to the power of negative 10 end exponent over denominator 1.602 space straight x space 10 to the power of negative 19 space straight x space 10 to the power of 6 end exponent end fraction space MeV straight i. straight e. comma space straight E space equals space 931. space 64 space MeV 1 space amu space equals space 931 space MeV$

441 Views

42. What is meant by analogue and digital signal ? What is the symbol for a XOR gate ?

338 Views

43. Draw a labelled circuit diagram of a simple oscillator (using PNP or NPN transistor in common emitter configuration). On what factors does the frequency of the oscillator depend ?

1322 Views

44. Draw energy band diagrams of conductors. semiconductors and insulators.

368 Views

Long Answer Type

45. In J.J. Thomson’s experiment for the determination of the ratio of the charge to the mass (e/m) for an electron, derive the formula in terms of E, B and V where E is the electric field intensity, B is the magnetic field intensity and V is the accelerating potential between anode and cathode.

575 Views

46.

For Bohr’s model of the hydrogen atom, the energy of electron in its ground state is found to be-13.6 eV.

(i) Draw an energy level diagram for the hydrogen atom and mark the values of energy (in eV) at n = 2 and n = ∝.

(ii) Obtain the maximum energy of a photon emitted by the hydrogen atom in eV.

329 Views

47.

(i) On what does the minimum wavelength of the continuous x-ray spectrum depend

(ii) When the filament current is increased, the intensity of the x-ray produced increases. Why?

(iii) Why is the structure of crystals studied by x-rays ?

443 Views