A step-up transformer in a microwave oven is connected to a 230 V ac mains supply. The transformer has an efficiency of 88% and delivers a current of 0.450 A at a secondary potential difference of 2.10 kV2.10\text{ kV}2.10 kV to the magnetron.
What is the current in the primary winding of the transformer under these operating conditions?
0.056 A0.056\text{ A}0.056 A
3.62 A3.62\text{ A}3.62 A
4.11 A4.11\text{ A}4.11 A
4.67 A4.67\text{ A}4.67 A