Under what condition does a junction diode work as open switch?

Under what conditions is work said to be done?

What is corpus luteum? Under what conditions does it undergo degeneration?

under what condition does a biconvex lens of glass having a certain refractive index act as a plane glass sheet,when immersed in a liquid?

Under what conditions the work done by a force is zero in spite of displacement being taking place?

Under what condition is the relation S= ut correct?