The winding of a transformer which is connected to a source of energy is called the ....... winding.

A transformer has 500 turns on its primary coil and 100
turns on its secondary coil. An a.c voltage of 25 V is
connected across the primary coil.
What is the voltage across the secondary coil?

TIPS!!!!!!
 $\frac{V_P}{V_S}=\frac{N_P}{N_S}=\frac{I_S}{I_P}$  

Diagram shows a simple transformer. The bulb does

not light up. Which modification will cause the bulb to light up?

Diagram shows a step up transformer. Which step will increase the efficiency of the transformer?

 $\frac{V_P}{V_S}=\frac{N_P}{N_S}$  

The Diagram shows the number of turns in the pair
of output terminal of a transformer. Which output terminal pair, the output voltage is 12V?

 $Efficiency,\ kecekapan\ =\ \frac{Po}{Pi}x\ 100\%\ =\ \frac{V_SI_S}{V_PI_P}\ x\ 100\%$  

When a transformer with its primary coil is connected
to a 240V a.c. supply, the current in the primary and
secondary coil is 12A and 5A respectively. If the
transformer is 80% efficient, what is the output voltage
of the secondary coil?