Never underestimate an old man who was born in September shirt

If you are using an analogue meter, you will see deflection of the pointer due to the magnetic field, not from reading the voltage. To find the open-circuit voltage, you need to put some insulating material (plastic or wood) between the electrodes. I assume you want to check the characteristics of the transformer but this is rarely done in this way. You do not say why you need to make this measurement.

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