# is it correct to say?

#### nicoke

is it correct to say;

applied emf= 6V
therefore,
back emf= -6V

??

neila9876

#### oz93666

I would say no .... the adjectives applied and back already impart a direction to the EMF ...one is going in the opposite direction to the other

in mechanics force is 5N resistance is 5N ...no movement .

#### studiot

Well it kind of depends upon circumstances (the circuit)

Just because the applied voltage is 6 volts it doe not mean that the back emf is also 6 volts.

The back emf may be more, less or even not exist at all.

So you cannot say 'therefore'.

In terms of your voltage sign conventions, yes you can say the applied voltage is +x volts and the back emf is -y volts.

But you have to know what these conventions are.

Remember the the plus or minus convention can be used for polarity (instantaneous alternating voltage phasor or direct voltage) or direction.

These are not the same.

#### neila9876

Of course oz93666 gave a correct answer (he always is a first rated technician). But the best teacher should point out why a mistaken appeared in a student's mind. This tramp in cosmos is not a teacher.

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#### Cervesa

in mechanics force is 5N resistance is 5N ...no movement .
... no change in movement.

neila9876

#### neila9876

What I am curious is why such a strange idea (the OP) appeared in a student's mind...