For the transformer circuit shown, if the turns ratio is 3 ∶ 1, then the power transferred to the load is  

The correct answer is option 4): (the maximum)

Concept:

• According to the maximum power transfer theorem, the maximum will be transferred to load resistance R_L when R_L is equal to Thevenin resistance R_th
• Let n is the turns ratio, When the secondary impedance Z_L­ is transformed to primary, it becomes n²Z_L The load resistance referred to primary = n² R_L
• The turn ratio is 

Calculation:

Given

The turns ratio is 3: 1 

The source resistance = n2ZL

According to the Maximum power transform theorem

3² ×  100 = 900

hence, For the transformer circuit shown, if the turns ratio is 3 ∶ 1, then the power transferred to the load is maximum.