Page 1 CBSE TEST PAPER-03 CLASS - XII PHYSICS (Unit – Current Electricity) 1. Resistivites of copper, silver and manganin are 1.7×10 -8 O m , 1.0×10 -8 O m and 44×10 -8 O m. respectively which of these is the best conductor ? [1] 2. Draw the graph showing the variation of conductivity with temperature for a metallic conductor? [1] 3. A set of n-identical resistors , each of resistance R ohm when connected in series have an effective resistance of X ohm and when the resistors are connected in parallel the effective resistance is Y ohm. Find the relation between R , X and Y ? [3] 4. Show the resistance of a conductor is given by 2 ml R ne A t = [3] 5. Two primary cells of emf’s E 1 and E 2 are connected to the potentiometer wire AB as shown in the figure if the balancing length for the two combinations of the cells are 250 cm and 400 cm. find the ratio of E 1 and E 2 . [3] 6. Explain with the help of a circuit diagram, how the value of an unknown resistance can be determined using a wheat stone bridge? [3] 7. Find the current drawn from a cell of emf IV and internal resistance 2/3 O connected to the network shown in the figure. E = 1v r = 2/3 O [3] 8. (a) State and explain kirchoff’s law? (b) In the network shown, find the values of current I1 , I2 and I3. [3] G G A B E 1 E 2 E 1 E 2 250cm 400cmRead More

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