A step-down transformer connected to an AC mains supply of $220\text{V}$ is made to operate at $11\text{V},44\text{W}$ lamp. Ignoring power losses in the transformer, what is the current in the primary circuit?

Q. A step down transformer is used to reduce the main supply of $220\text{V}$ to $10\text{V}$. If the primary draws $5\text{A}$ and secondary draws $88\text{A}$ current, calculate the efficiency of the transformer.

Q. (i) Draw a labelled diagram of a step-down transformer. State the principle of its working.
(ii) Express the turns ratio in terms of voltages.
(iii) Find the ratio of primary and secondary currents in terms of turns ratio in an ideal transformer.
(iv) How much current is drawn by the primary of a transformer connected to 220 V supply when it delivers power to a 110 V - 550W refrigerator ?

Q. A step down transformer reduces 220 V to 11 V. The primary coil draws 5 A current and secondary coil supplies 90 A. Efficiency of the transformer will be:

Q. A transformer is used to light a $200W$ and $110V$ lamp from $220V$ main supply. If the main current is $1A$, then efficiency of transformer, is

Q. How much current is drawn by the primary of a transformer connected to $220V$ supply when it delivers power to a $110V-550W$ refrigerator?