Current Electricity Test Paper 03 - Class 12

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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 400cm