Arch welding voltage (open circuit) ranges between 20V and 100V. AC electric current at 415 V and 50Hz is supplied to an arch welding transformer that steps down the voltage to 35V for welding. Calculate the number of turns in the primary coil when the secondary coil has 40 turns.

In a power distribution network, electricity is transmitted from a power plant to a substation at a voltage of 132 kV. A transformer then steps down this high voltage to a voltage of 11 kV for distribution within an industrial area. In an ideal transformer, the output power from the secondary coil is equal to the input power to the primary coil. If the secondary coil of a transformer supplies 625 A at 11 kV to the industrial area, calculate the current in the 132 kV line from the power plant.

An electric transformer with an efficiency rate of 75% is hooked up to a 120-V AC source. The secondary coil is linked to a 60-W lamp with a resistance value of 3-Ω. (a) What is the current flowing through the primary coil of the transformer? (b) What is the winding ratio of this transformer?