thumb-and-finger rule

noun

Definition of thumb-and-finger rule

: either of two statements in electromagnetism: when the fingers of the right hand are bent so that the thumb points in the direction of the decrease in flux in a magnetic circuit, the fingers will point in the direction of the induced voltage in the electric circuit linked with the magnetic circuit; and when the fingers of the right hand are bent so that they follow the direction of the flow of current through a helical or coil conductor, the thumb will point in the direction of the flux through the helix or coil — compare left-hand rule, right-hand rule

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“Thumb-and-finger rule.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/thumb-and-finger%20rule. Accessed 30 Jun. 2022.

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