Transformers Questions

• Transformer fundamentals — identifying input and output windings: In a conventional transformer used for power or signal isolation, which statement correctly identifies the typical roles of the windings?
• Transformer secondary current effect: If the number of turns on the secondary of an ideal transformer is increased (with the same primary drive and the same load impedance referred to its own side), what happens to the secondary current?
• Mutual inductance from coupling coefficient: Two coils have L1 = 75 mH and L2 = 105 mH with coefficient of coupling k = 0.45. What is the mutual inductance M between the coils?
• Impedance matching with an ideal transformer: What turns ratio (primary:secondary) is required to match a 1 kΩ source resistance to a 160 Ω load?
• Principle of mutual induction — key dependency: Mutual induction between two coils primarily depends on which factor in operation?
• Signal interfacing in RF and audio systems: A special transformer designed to convert an unbalanced (single-ended) signal to a balanced (differential) signal is called a:
• Maximum power transfer theorem in circuit design: Under what condition does a source deliver maximum power to a load (assume resistive source/load)?
• Ideal transformer power conservation: An ideal transformer has a 2:1 voltage ratio (primary:secondary) and delivers 100 W at the primary. What is the secondary power output?
• Transformer efficiency calculation: A 120 V rms primary draws 300 mA rms. The secondary supplies 18 V across a 10 Ω load. Compute the efficiency η = P_out / P_in.
• What does a transformer's turns ratio determine in practical circuits (assume linear operation)?
• In the given circuit, the secondary voltage is in phase with the primary voltage.
• Regardless of whether the transformer is step-up or step-down, power in the primary equals the power in the secondary if there is 100% efficiency.
• The reflected load value that the source sees will always be larger than the load value itself.
• If the current drawn in the secondary of a transformer increases, the power in the primary should remain the same.
• The secondary voltages produced by a center-tapped transformer are equal in amplitude but 180° out of phase with respect to the center tap.
• An open secondary winding of a transformer will cause the primary current to be nearly zero.
• If voltage is stepped-up to the secondary, current will be stepped-down by the same amount.
• A transformer that has 700 turns in the primary and 35 turns in the secondary has a turns ratio of 20:1.
• In the given circuit, Maximum power is being transferred to the load.
• For mutual inductance to occur, the two coils must be at right angles to each other.