CBSE XII (AISSCE) 2006 Question Paper

Outside Delhi

Define the term electric dipole moment. Is it a scalar or a vector quantity. The variation of potential difference V with length l in case of two potentiometers P and Q ia as shown. Which one of these two will you prefer for comparing the e.m.f.s of two primary cells? de Broglie wavelength associated with an electron accelerated through apotential difference V is ?. What will be its wavelength when the acceleratingpotential is increased to 4 V? Give any one difference between FAX and e-mail systems of communication. Steel is preferred for making permanent magnets whereas soft iron is preferred for making electromagnets. Give one reason. You are given ‘n’ resisitors, each of resistance ‘r’. These are first connected to get minimum possible resistance. In the second case, these are again connected differently to get maximum possible resistance. Compute the ratio of the minimum to the maximum values of resistance obtained. Two capacitors of capacitance 6?F and 12?F are connected in series with a battery. The voltage across the 6 ?F capacitor is 2 V. Compute the total battery voltage. OR A parallel plate capacitor with air between the plates has a capacitance of 8 pF. The separation between the plates is now reduced by half and the space between them is filled with a medium of dielectric constant 5. Calculate the value of the capacitance of the capacitor in the second case. Draw a labelled ray diagram to show the image formation in a refracting type astronomcal telescope. Why should the diameter of theobjective of a telescope be large? Draw a circuit diagram of a metre bridge and write the necessary mathematical relation used to determine the value of an unknownresistance. Why cannot such an arrangement be used for measuring very low resistances? Which one of the two, an ammeter or a milliammeter, has a higher resistanceand Why? An alternating voltage of frequency f is applied across a series LCR circuit. Let frbe the resonance frequency for the circuit. Will the current in the circuit lag, lead or remain in phase with the appiled voltage when (i)f>fr (ii) f<fr?Explain your answer in each case. A point charge ‘q’ is placed at O as shown in the figure. Is VP – VQ positive or negative when (i) q>0 (ii) q<0?Justify your answer. Using Gauss’ theorem, show mathematically that for any point outside the shell, the field due to a uniformly charged thin sphericalshell is the same as if the entire charge of the shell is concentrated at the centre. Why do you expect the electric field inside the shell

to be zero according to this theorem? read more

  • Distinguish between frequency modulation and amplitude modulation. Why is an FM signal less susceptible