we all know that according ti kirchoff's loop rule , the potential difference across a loop is zero then how emf induces in a close loop when a bar magnet is taken away or towards it ?

Can you clarify the question a bit more? Sounds like the answer is a quick, simple: Because faraday was a friggin BOSS.

 

But what he discovered was more about wires that contained multiple loops as part of a circuit.

 

Or, are you asking about a literal single loop with nothing outside that loop. If you tried to faradize a ring of wire, I'm not sure you would get a voltage because although there would be electromagnetic pressure.... It would be uniform. No pressure differential, no motion.

we all know that according ti kirchoff's loop rule , the potential difference across a loop is zero then how emf induces in a close loop when a bar magnet is taken away or towards it ?

I thought Kirchoff's law was to do with electrical current, such that the currents entering a given junction must equal the currents leaving it.

we all know that according ti kirchoff's loop rule , the potential difference across a loop is zero then how emf induces in a close loop when a bar magnet is taken away or towards it ?

 

 

Why is the potential difference across a loop zero?

Because electron gains no energy when making one round around the loop.

 

Why does electron not gain any energy?

Because the EMF pushes an electron, but friction force pushes an electron into the opposite direction.

 

In this "abnormal" circuit that we are discussing here, at every point of the circuit EMF = friction force.

In a "normal" circuit EMF is less homogeneously distributed.

In the closed loop, you have more elements than the circuit portion where the EMF is induced. For instance the voltmeter that measures the induced voltage.

 

It could be resistors that drop this voltage, batteries, capacitors, coils that store the produced electrical energy...

I thought Kirchoff's law was to do with electrical current, such that the currents entering a given junction must equal the currents leaving it.

there are two rules one is junction rule which you have said and another is loop rule about which i was asking

In the closed loop, you have more elements than the circuit portion where the EMF is induced. For instance the voltmeter that measures the induced voltage.

 

It could be resistors that drop this voltage, batteries, capacitors, coils that store the produced electrical energy...

i didn't understand would you please more specify it ?

Kirchoff's rules have little or nothing to do with bar magnets and induction. That is Faraday's law.

Kirchoff's laws enable you to solve (linear) electrical circuits for voltage and current, given the connectivity between components.