K.C.S.E Physics Q & A - MODEL 2011PP2QN15

K.C.S.E Physics Q & A - MODEL 2011PP2QN15

​(a) Figure 8, shows a graph of potential difference V (volts) against a current I (amperes) for a certain device.

​From the graph:
(i) state with a reason whether or not the device obeys ohms law. 
(ii) determine the resistance of the device at:
(1) 1 =l.5A 
(II) I =3.5A 
(iii) From the results obtained in (ii) state how the resistance of the device varies as the current increases. 
(iv) State the cause of this variation in resistance. 
(b) Three identical dry cells each of e.m.f. 1 .6V are connected in series to a resistor of 11.4 ohms. A current of 0.32A flows in the circuit. Determine:
(i) the total e.m.f. of the cells;
(ii) the internal resistance of each cell; 

answers