Where can superposition be used and not be used in a circuit or device?

Answer 1

most devices have physical restraints

a permanent magnet dc motor a very linear device

voltage yields rpm

good example and bidirectional

- voltage doesnt mean -rpm but it will turn the other way at the same speed

if input voltage a yields x rpm

a => x

if input voltage b yields y rpm

b => y

superposition implies

(A+B) =>( x+y)

12v dc motor

volts rpm

0 0

.5 0

1 100

3 300

6 600

9 900

12 1200

so if a= 3v b= 6v

a+b => 900 rpm

the .5 up there is where with the small voltage we dont have enough torque to overcome friction and inertia

at the low end no way to predict when the motor will start

after we get it moving maybe we can run at 50rpm with .5V

say for a we chose12V and for b we chose 12 v

does this mean at 24v the motor will run 2400 rpm?

or is there some reason besides superposition that we call this a 12V motor?

most physical things have boundary conditions