The number of turns on the coils of four ideal iron-cored transformers A, B, C and D are shown in the table below.

Each transformer is connected in turn to an alternating 240 V supply.

Which transformer will give the largest output current?

The National Grid is used to transfer electrical energy from power stations to consumers.

What conditions for the transmission voltage and the transmission current give the most efficient transfer of energy through the National Grid?

A mains transformer has a primary coil of 2500 turns and a secondary coil of 130 turns.

The primary coil is connected to a mains supply where V_rms is 230 V.

The secondary coil is connected to a lamp of resistance 6.0 Ω.

The transformer is 100% efficient.

What is the peak power dissipated in the lamp?

The primary winding of a transformer has 200 turns and the secondary winding has 1600 turns.

A root mean square (rms) alternating voltage of 25 V is applied to the primary winding causing a primary rms current of 4.0 A. The transformer is 90% efficient.

What are the rms values of the secondary voltage and the secondary current?

A transformer has an efficiency of 80%.

It has 7000 turns on its primary coil and 175 turns on its secondary coil. When the primary of the transformer is connected to a 240 V ac supply, the secondary current is 8.0 A

What are the primary current and secondary voltage?