instruction:
In this task you will be given an answer to a question. You need to generate a question. The answer given should be a correct answer for the generated question.
question:
The origin of the custom may be in German folklore, where in supernatural beings are thought to live in trees, and can be invoked for protection.
answer:
where did the term knock on wood originate

question:
Dornacker was also an actress. She appeared in playwright Sam Shepard's jazz opera Inacoma at San Francisco's Magic Theatre (1977) and was featured in other works by the Overtone Theatre. She appeared in The Stand-Up, Anita Sperm and as the mysterious Nurse Murch in the film The Right Stuff -- she can be seen asking an astronaut for a semen sample.
answer:
who played nurse murch in the right stuff

question:
The LVDT converts a position or linear displacement from a mechanical reference (zero, or null position) into a proportional electrical signal containing phase (for direction) and amplitude (for distance) information. The LVDT operation does not require an electrical contact between the moving part (probe or core assembly) and the coil assembly, but instead relies on electromagnetic coupling.
answer:
when do you obtain null position in lvdt