# 18. Class 12th Physics | Current Electricity | Electromotive Force (EMF) | by Ashish Arora

let us study about electromotive force. this
is term which is also abbreviated as e m f. and now onward we are going to use the term
e m f, very frequently, in this chapter, as well as in the, coming topics. about e m f
we can write that. any devices. which can. continuously. supply energy. to flow. current
in electrical circuits. are called. electromotive, forces. or e m f’s. we can write such devices.
which are called e m f’s. transform energy. from. non-electrical forms. to electrical
forms. like we can discuss some examples, these 2 points you need to always keep in
mind about e m f’s. if we talk about a battery. we can state that the battery transforms.
chemical energy. to electrical energy. if we talk about a generator. a mechanical generator.
it transforms. mechanical energy to electrical energy. however there are various ways, in
which the mechanical energy can be generated. using like. a mechanical generator or. thermoelectric
generator, or. hydroelectric generator like that. similarly if we talk about a nuclear
reactor. which also uses generator but here we can say. it transforms. energy of. nuclear
reactions. to. electrical energy. so these all devices a battery a generator and a nuclear
reactor these can be termed as e m f’s. and generally e m f term. is used, this term.
is used. to represent. the open circuit. potential difference. across the device terminals. which
gives us an idea about the strength of e m f also like if there is a battery of 10 volt.
and there is a battery of 50 volt. which is the open circuit potential difference across
a battery this 10 volt 50 volt gives us the, idea about the e m f strength of the battery
so we can say battery of e m f 50 volt. supplies a current into the circuit, similarly a generator
of hundred volt 500 volt. thousands volts. this gives us an idea about the potential
difference which the generator can produce across its terminals in open circuit conditions.
so in general now onwards we are going to use e m f to represent. the open circuit potential
difference across the terminals of such devices. which transform. a non-electrical energy form
to the electrical energy form.

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## 9 thoughts on “18. Class 12th Physics | Current Electricity | Electromotive Force (EMF) | by Ashish Arora”

1. TheJae3013 says:

This was a more problem based definition.
The actual definition should be the work done by battery in order to move charge from negative terminal to the positive terminal i.e to maintain a constant potential difference across the terminals is termed as EMF of a battery.

2. nimish bansal says:

sirji what do we mean by open circuit potential differencesÂ  đź™‚Â  ?

3. study says:

wrong definition for EMF!

4. Sai Teja says:

Sir does it vary depending on charging and discharging of battery

5. Anshul Pareek says:

sir what is the open circuit potential difference. what the potential difference will be if the circuit is closed

6. Kiran Buch Jaib says:

Sir what is EMF sir it is a potential

7. yash agrawal says:

sir some topics are left in this chapter like color code of resistors , star delta conversion, symmetry circuits and many more. please sir look upon this as i am totally dependent on your lectures. thank you sir in advance.

8. Harry Kane says:

Never knew devices are called EMF

9. Rohit Shukla says:

Sir many topics are remaining i.e color code of resistor