# Electromotive Force Questions

The electromotive force is represented by the acronym EMF. It is described as the electric potential generated by the changing magnetic field or electrochemical cells. EMF is measured in volts. It is the energy per unit electric charge transmitted by an energy source, such as a battery or generator.

Where,

• ε – electromotive force
• I – current across the circuit
• V – voltage of the cell
• r – internal resistance of the cell

EMF = Joules/ Coulombs

M1 L2 T-3 I-1 gives the dimension of the electromotive force.

We know that energy is converted from one form to another. A battery or generator is an ideal example of energy conversion from one form to another. One terminal is positively charged in a battery, and another is negatively charged. Hence, an electromotive force is done on a unit electric charge.

Note that EMF remains constant. Electromotive force is independent of circuit resistance. EMF can also be negative. The production of a circulating electric field by a time-dependent magnetic field is known as electromagnetic induction.

## Important Electromotive Force Questions with Answers

1. The generator converts mechanical energy to _____.

1. Solar energy
2. Chemical energy
3. Electrical energy
4. Hydroelectric energy

Explanation: The generator is a device that converts mechanical energy to electrical energy.

2. State true or false: An electrochemical cell can generate electric potential.

1. TRUE
2. FALSE

Explanation: Electric potential is generated by changing the magnetic field or by an electrochemical cell.

3. What is the formula to find the EMF?

1. ε = V – Ir
2. ε = V*Ir
3. ε = V + Ir
4. ε = V/Ir

Answer: c) ε = V + Ir

4. Is electromotive force a scalar or a vector quantity?

Electromotive force is a scalar quantity. Note that electromotive force is not a force.

5. What is the unit of EMF?

1. Watts
3. Volt
4. Seconds

Explanation: The unit of EMF is volt.

6. The production of voltage in a coil because of the change in magnetic flux through a coil is known as _____

1. Induced magnetism
2. Induced current
3. Electromagnetic induction
4. Chemical induction

Explanation: Electromagnetic induction, also known as EMF Induction, refers to the generation of voltage in a coil due to the change in magnetic flux in it.

7. The electromotive force is represented using the symbol_____.

1. $$\begin{array}{l}\alpha\end{array}$$
2. $$\begin{array}{l}\varepsilon\end{array}$$
3. $$\begin{array}{l}\rho\end{array}$$
4. $$\begin{array}{l}\vartheta\end{array}$$

$$\begin{array}{l}\varepsilon\end{array}$$

8. Give the formula to find an electromotive force that is induced by a straight conductor moving in a magnetic field.

It is given by the formula: E = B*l*v

Where,

E = electromotive force

B = magnetic field

l = length of conductor

v = velocity of conductor

9. State true or false: an electromotive force is a work done on a unit electric charge.

1. TRUE
2. FALSE

10. Batteries convert chemical energy to _____

1. Solar energy
2. Chemical energy
3. Electrical energy
4. Hydroelectric energy

Explanation: Batteries convert chemical energy into electrical energy.

## Practice Questions

1. Define electromotive force
2. What is meant by induced EMF?
3. Which devices work on the principle of electromotive force?
4. What is the dimension of electromotive force?
5. What is meant by potential difference?

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