-this is what thetextbook says about transformers A transformer is adevice that
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Question
-this is what thetextbook says about transformersA transformer is adevice that increases or decreases the voltage of an alternatingcurrent. A transformer is made of a primary coil and a secondarycoil. These wire coils are wrapped around the same iron core. As analternating current passes through the primary coil, the coilsmagnetic field magnetizes the iron core. The magnetic field in theprimary coil changes direction. This produces a magnetic field inthe iron core that changes direction at the same frequency. Thechanging magnetic field in the iron core then induces analternating current with the same frequency in the secondarycoil.
The voltage in the primary coil is the inputvoltage and the voltage in the secondary coil is the outputvoltage. The output voltage divided by the input voltage equals thenumber of turns in the secondary coil divivded by the number ofturns in the primary coil.
Explain why the output voltage from a transformer is zeroif a direct current flows through the primarycoil.
Explanation / Answer
As stated, the emf is induced in secondaryonly when the current in primary changes. Since the current in caseof DC is constant, there is no change in magnetic field throught hecore and hence no voltage is induced in secondary coil.Related Questions
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