Board Exam physics Important Topics

[Nitin Sharma]

I want to know about information about important topics for physics subject in class 12th examination of CBSE board ?

Here I am giving you information about important topics for physics subject in class 12th examination of CBSE board below :

Important topics :
Electrostatics
Current Electricity
Magnetic effect & Magnetism
Electromagnetic induction & Alternating currents
Electromagnetic Waves
Optics
Dual Nature of Matter
Atoms & Nuclei
Electronic Devices
Communication Systems

Sample questions :
The graph shown here, shows the variation of the total energy (E) stored in a capacitor against the value of the
capacitance(C) itself. Which of the two - the charge on the capacitor or the potential used to charge it is kept
constant for this graph?

2. An - particle and a proton are moving in the plane of the paper in a region where there is a unifom magentic field
( ) directed normal to the plane of the paper. If the two particles have equal linear momenta, what will be the ratio
of the radii of their trajectories in the field? 1

3. State the condition under which a microwave oven heats up a food item containing water molecules most
efficiently. 1
(41)
4. An electrical element X, when connected to an alternating voltage source, has the current through it leading the
voltage by radii. Identify X and write an expression for its reactance. 1
5. A double convex lens, made from a material of refractive index , is immersed is a liquid of refractive index
where . What change, if any, would occur in the nature of the lens? 1

6. The de Broglie wavelengths, associated with a proton and a neutron, are found to be equal. Which of the two has
a higher value for kinetic energy? 1

7. Carbon and silicon are known to have similar lattice structures. However, the four bonding electrons of carbon are
present in second orbit while those of silicon are present in its third orbit. How does this difference result in a
difference in their electrical conductivities? 1

8. An unknown input (A) and the input (B) shown here, are used as the two inputs in a NAND gate. The output Y, has
the form shown below. Identify the intervals over which the input ‘A’ must be ‘low’.
1

9. The two graphs drawn below, show the variation of electrostatic potential (V) with (r being distance of the field
point from the point charge) for two point charges q1 and q2.
(42)
(i) What are the signs of the two charges?
(ii) Which of the two charges has a larger magnitude and why? 2
10. Calculate the temperature at which the resistance of a conductor becomes 20% more than its resistance at 270C.
The value of the temperature coefficient of resistance of the conductor is . 2
11. A student records the following data for the magnitudes (B) of the magnetic field at axial points at different
distances x from the centre of a circular coil of radius a carrying a current I. Verify (for any two) that these
observations are in good agreement with the expected theoratical variation of B with x.
x = 0 x = a x = 2a x = 3a
2
12. An armature coil consists of 20 turns of wire, each of area A = 0.09m2 and total resistance 15.0 . It rotates in a
megnetic field of 0.5T at a constant frequency of . Calculate the value of (i) maximum (ii) average
induced emf produced in the coil 2
13. Two cells of emf E1 and E2 have internal resistance r1 and r2. Deduce an expression for equivalent emf of their
parallel combination.
OR
A cell of emf (E) and internal resistance (r) is connected across a variable external resistance (R).
Plot graphs to show variation of