---
title: "Meaning of emf of a cell"
subject: "Engineering Chemistry"
chapter: 1
key: "semester_2/engineering_chemistry:emf-of-cell"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/emf-of-cell
site: BCT Engineering
---

# Meaning of emf of a cell

Engineering Chemistry · Chapter 1: Electro-chemistry and Buffer

- Asked in: 2072 Magh, 1 marks
- Video: [EMF of a cell| Calculate emf of a cell| Reduction potential Electrochemistry Chapter-2 Class12](https://www.youtube.com/watch?v=E5L312Te6fo) — Preetika Chauhan
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/emf-of-cell
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-1

## Question

What is meant by emf of a cell?

## Short answer

The emf of a cell is the potential difference between its electrodes when no current is drawn; it equals the maximum voltage E(cathode) − E(anode), measured in volts.

## Answer

The **emf (electromotive force) of a cell** is the potential difference between the two electrodes of a galvanic cell when no current is drawn from it (open circuit). It is the maximum voltage the cell can give, and equals E(cathode) − E(anode), measured in volts.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. The emf of a cell is the potential difference between its electrodes when:
   A. Maximum current flows
   B. The cell is short-circuited
   C. No current is drawn (open circuit)
   D. The cell is discharged
   Answer: C. emf is measured under open-circuit conditions and is the maximum voltage. (Key point: Definition of emf)

2. emf is given by:
   A. E(anode) - E(cathode)
   B. E(cathode) + E(anode), both reduction
   C. E(cathode) - E(anode), using reduction potentials
   D. E(cathode) x E(anode)
   Answer: C. emf = E(cathode) - E(anode) in terms of reduction potentials. (Key point: Formula)

3. Which statement about emf is correct?
   A. It is the minimum voltage the cell gives
   B. It is zero for a working cell
   C. It is the maximum voltage the cell can give
   D. It is measured in amperes
   Answer: C. The open-circuit potential difference is the maximum voltage obtainable, in volts. (Key point: Meaning)

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