If internal resistance of each cell is much greater than the external resistance, which combination gives the maximum current? Explain.

The current in the series combination of n cells, I s = n E n r + R The current in the parallel combination of n cells, I p = E r / n + R where, E : EMF of each cell r : Internal resistance R : External resistance It is given that, the internal resistance of each cell is much greater than the external resistance, Then, in series combination, n r > R Current in series combination, I s = E r In parallel combination, r n > R Current in parallel combination, I P = n E r Thus, maximum current will be obtained from the parallel combination of cells.

The resistance of carbon resistor is 7600 + 20 % ohms. Write the order of colour rings for it.

Carbon resistors have different colour bands or different colour rings which have a specific value. We are given a carbon resistor, having resistance 7600 + 20 % Ω It can be written as: 76 × 100 ± 20 % Ω = 76 × 10 2 ± 20 % Ω The first digit is 7 , thus the first colour is Violet The second digit is 6 , thus the second colour is Blue The third value is 10 2 , thus the third colour is Red. There is no fourth colour present, thus, the tolerance is 20 % The order of rings is: Violet, Blue and Red.