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WORKSHEET 3(CURRENT ELECTRITY )


               1)Three identical cells, each of emf 4 V  and internal resistance r, are connected in series to a 6 Ω
               resistor. If the current flowing in the circuit is 2 A. The internal resistance of each cell is:
               (a)0.11  Ω                   (b)5 Ω                    (c)0.12  Ω                                  (d)none of these

               2)If cells are joined in series, they have:
               (a)same internal resistance     (b)same potential difference     (c)same emf      (d)same current

               3)To get maximum current in a resistance of 3 Ω ,one can use m rows of n cells each (connected in
               series), connected in parallel. If the total number of cells is 24 and the internal resistance of a cell is 0.5
               Ω, then:
               (a)m=12,n=2                   (b)m=8,n=3                         (c)m=2,n=12                          (d)m=6,n=4

               4)Six lead acid type of secondary cells ,each of emf 2 V and internal resistance 0.015 Ω, are joined in
               series to provide a supply to resistance of 8.5 Ω.The current drawn from the supply is…………………


               5)Three cells of emf’s 2.0 V, 1.8 V and 1.5 V are connected in series.  Their internal resistances are 0.05
               Ω,0.7 Ω and 1 Ω, respectively. If this battery of three cells is connected to an external resistor  of 4 Ω via
               a very low resistance ammeter. The reading in the ammeter would be……………………

               6)A combination of two or  more cells is called a …………………..

               7)A number of identical cells(n), each of emf E ,internal resistance r, connected in series are charged by
               a d.c source of emf E’, using a resistor R. Draw the circuit arrangement.


               8)A (i)series (ii)parallel combination of two given resistors is connected one by one across a cell. In
               which case will the terminal potential difference across the cell have higher value?

               9)A parallel combination of two cells of emf  E 1 and E 2 ,and internal resistances r 1 and r 2 is used to supply
               current to a load of resistance R. Write the expression for the current through the load in terms of
               E 1,E 2,r 1 and r 2.

               10)When cells are connected in parallel, what is the effect on (i)current capacity (ii)emf of the cells.
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