Question

What is the main difference between a cell and a battery? In which conditions do the following combinations of cells become useful and why?
(i) Series combination
(ii) Parallel combination
(iii) Mixed combination

Hint:

Series combination increases voltage, parallel combination increases current, and mixed combination balances both.

Answer 1

A cell is a single electrochemical unit that converts chemical energy into electrical energy, while a battery consists of multiple cells connected together to provide higher voltage or current. 

Step 1: A cell generates electrical energy from a chemical reaction within a single unit. 

Step 2: A battery consists of multiple interconnected cells to provide higher output for more demanding applications. \[ \boxed{\text{Cell: Single unit, Battery: Multiple cells}} \]

(i) Series Combination 

Solution: In a series combination, the voltages add up while the current remains the same. 

Step 1: Cells are connected end-to-end, with the positive terminal of one connected to the negative terminal of the next. 

Step 2: The total voltage is: \[ V_{\text{total}} = V_1 + V_2 + V_3 + \dots \] 

Step 3: This configuration is useful when high voltage is required, such as in electronic circuits. \[ \boxed{\text{Used for high voltage applications.}} \] 

(ii) Parallel Combination 

 Solution: In a parallel combination, the current increases while the voltage remains the same. 

Step 1: Cells are connected with all positive terminals together and all negative terminals together. 

Step 2: The total current is: \[ I_{\text{total}} = I_1 + I_2 + I_3 + \dots \] 

Step 3: This configuration is useful when a higher current capacity is needed, such as in power backup systems. \[ \boxed{\text{Used for high current applications.}} \] 

(iii) Mixed Combination 

Solution: Step 1: In mixed combination, cells are connected in both series and parallel configurations. 

Step 2: This provides an increase in both voltage and current, depending on the number of cells. 

Step 3: It is useful in applications where both high voltage and current are needed, such as in electric vehicles. \[ \boxed{\text{Used for balanced voltage and current applications.}} \]