What transformer has the primary and secondary connected together in one winding?

• A. Amplifier
• B. Autotransformer
• C. Armature
• D. Arc

Answer: (B)

This question tests understanding of autotransformers. In an autotransformer, the primary and secondary windings are connected as a single continuous winding with taps. The voltage applied to the whole winding creates a portion of that voltage at a tap that serves as the secondary, so the same conductor carries both input and output currents. Because the windings share a section, the secondary voltage is simply the fraction defined by the tap position relative to the full winding. This arrangement makes autotransformers compact and efficient for voltage changes when isolation between primary and secondary isn’t required. In contrast, a two-winding transformer uses separate windings with electrical isolation, which is not the configuration described. The other options—amplifier, armature, and arc—do not describe a transformer with primary and secondary on one winding.