PhysicsLAB CP Workbook
Transformers

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Refer to the following information for the next seven questions.

Consider a simple transformer that has a 100-turn primary coil and a 1000-turn secondary coil. The primary is connected to a 120-V AC source and the secondary is connected to an electrical device with a resistance of 1000 ohms.
What will be the voltage output of the secondary? 

What current flows in the secondary circuit? 

Now that you know the voltage and the current, what is the power in the secondary coil? 

Neglecting small heating losses, and knowing that energy is conserved, what is the power in the primary coil? 

Now that you know the power and the voltage across the primary coil, what is the current drawn by the primary coil? 

These results show that the voltage was stepped
 
from primary to secondary, and that the current was correspondingly stepped
 



For a step-up transformer, there are ____ turns in the secondary coil than the primary.
 
For such a transformer, there is ___ current in the secondary than in the primary.
 



A transformer can step up
 
but in no way can it step up
 



If 120 V is used to power a toy electric train that operates on 6 V, then a
 
transformer should be used that has a primary to secondary turns ratio of
 



A transformer operates on
 
because the magnetic field within the iron core must
 







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