1. TRANSFORMERS

2. Transformers- used to increase or decrease the voltage
Step down transformer- more coils are on the primary than on the secondary. Will decrease the voltage.

3. Step-up transformer- Used to increase the voltage
Step-up transformer- Used to increase the voltage. Has more coils on the secondary.
*Transformers work with alternating current only*

4. FORMULA’S VP NP V-voltage N – number of coils VS NS I – current
p ,s subscripts-indicate the primary and secondary coils of the transformer
VP NP
VS NS
VP IP =VS IS
%efficiency = power out X 100
power in

5. EXAMPLE
A step-up transformer has 200 coils on the primary and 3000 on the secondary. The primary has a potential difference of 90V.
a) What is the potential difference in the
secondary?
VP NP V/ Vs= 200/ 3000
VS NS
Vs = 1350V

6. Pout= 1350V(2Amp) Pout=2700 Watts
b) If the current in the primary is 30Amp, what is the current in the secondary?
VP IP =VS IS
90V(30Amp)= 1350V(Is )
Is = 2 Amps
c) What is the power output of the transformer?
Pout = VS IS
Pout= 1350V(2Amp)
Pout=2700 Watts

7. Step-up Step-down