What is Parallel Combination of Cells? | Simple Explanation for Class 10

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What is the Parallel Combination of Cells?

Grade Level:

Class 10

AI/ML, Physics, Biotechnology, Space Technology, Chemistry, Engineering, Medicine

Definition

What is it?

The parallel combination of cells is when the positive terminals of all cells are connected together, and similarly, all negative terminals are connected together. This arrangement keeps the voltage (or potential difference) across the combination the same as that of a single cell, but it increases the total current capacity.

Simple Example

Quick Example

Imagine you have two mobile power banks, each giving 5 Volts. If you connect them in parallel, you still get 5 Volts, but now you can charge your phone for a much longer time or even charge two phones at once! It's like having more fuel in your car, not a faster engine.

Worked Example

Step-by-Step

PROBLEM: Three cells, each with an electromotive force (EMF) of 1.5 V and internal resistance of 0.5 ohm, are connected in parallel. What is the total EMF and the total internal resistance of the combination?---STEP 1: Identify the EMF of a single cell. Given, EMF (E) = 1.5 V.---STEP 2: For cells connected in parallel, the total EMF (E_total) remains the same as the EMF of a single cell. So, E_total = 1.5 V.---STEP 3: Identify the internal resistance of a single cell. Given, internal resistance (r) = 0.5 ohm.---STEP 4: For cells connected in parallel, the reciprocal of the total internal resistance (1/r_total) is the sum of the reciprocals of individual internal resistances. Since there are 3 identical cells: 1/r_total = 1/r + 1/r + 1/r = 3/r.---STEP 5: Substitute the value of r: 1/r_total = 3 / 0.5 = 6.---STEP 6: Calculate r_total: r_total = 1/6 ohm.---ANSWER: The total EMF of the combination is 1.5 V, and the total internal resistance is 1/6 ohm (approximately 0.167 ohm).

Why It Matters

Understanding parallel cell combinations is key for designing reliable power systems in electric vehicles, solar power setups, and even for emergency backup power. Engineers use this concept in AI/ML hardware, Space Technology, and Biotechnology to ensure devices have enough power for long durations.

Common Mistakes

MISTAKE: Students often think that connecting cells in parallel increases the total voltage. | CORRECTION: The total voltage (EMF) in a parallel combination of identical cells remains the same as that of a single cell. The current capacity increases.

MISTAKE: Assuming that the formula for total resistance in series (R_total = R1 + R2 + ...) applies to internal resistance in parallel. | CORRECTION: For internal resistance in parallel, you use the reciprocal formula: 1/r_total = 1/r1 + 1/r2 + ...

MISTAKE: Forgetting that the internal resistance also contributes to the total resistance of the circuit. | CORRECTION: Always consider the internal resistance of cells when calculating total resistance, especially in parallel combinations where it significantly reduces the overall internal resistance.

Practice Questions

Try It Yourself

QUESTION: Two cells, each of 2 V EMF and 0.1 ohm internal resistance, are connected in parallel. What is the total EMF of the combination? | ANSWER: 2 V

QUESTION: Four identical cells, each with an internal resistance of 0.8 ohm, are connected in parallel. Calculate the total internal resistance of this combination. | ANSWER: 0.2 ohm

QUESTION: A circuit needs a stable 1.5 V supply and can draw a maximum current of 10 A. If you have cells each providing 1.5 V and having an internal resistance of 0.3 ohm, how many such cells should you connect in parallel to achieve a total internal resistance of 0.05 ohm? | ANSWER: 6 cells

MCQ

Quick Quiz

When identical cells are connected in parallel, what happens to the total EMF and total internal resistance?

EMF increases, internal resistance increases

EMF stays same, internal resistance decreases

EMF decreases, internal resistance stays same

EMF stays same, internal resistance increases

The Correct Answer Is:

In a parallel combination of identical cells, the total EMF remains the same as that of a single cell, while the total internal resistance decreases because there are more paths for the current.

Real World Connection

In the Real World

Many electric vehicles (EVs) like Ola Electric scooters or Tata Nexon EVs use large battery packs made of thousands of individual cells connected in both series and parallel. The parallel connections help increase the total current capacity, allowing the vehicle to run for longer distances on a single charge.

Key Vocabulary

Key Terms

EMF: Electromotive Force, the voltage produced by a cell when no current is drawn | INTERNAL RESISTANCE: The opposition offered by the cell's electrolyte and electrodes to the flow of current | PARALLEL CONNECTION: A way of connecting components where positive terminals are joined together and negative terminals are joined together | CURRENT CAPACITY: The maximum amount of current a power source can deliver over time

What's Next

What to Learn Next

Now that you understand parallel combinations, you should explore 'What is the Series Combination of Cells?'. This will help you see how different connections affect voltage and current, preparing you for more complex circuit designs.