[" 65.Electrons of mass "m" with de-Broglie wavelength "lambda" fall on the target in an X-ray tube.The cutoff wavelength "],[[(lambda_(0))" of the "2mc lambda^(2)," (2) "lambda_(0)=(2h)/(mc)]],[[" (1) "lambda_(0)=(2mc lambda^(2))/(h)," (2) "lambda_(0)=(2h)/(mc)," (3) "lambda_(0)=(2m^(2)c^(2)lambda^(3))/(h^(2))," (4) "lambda_(0)=lambda]],[[" (1) "lambda_(0)=(2mc lambda^(2))/(h)," (2) "lambda_(0)=(2h)/(mc)," (3) "lambda_(0)=(2m^(2)c^(2)r^(3))/(h^(2))," (4) "lambda_(0)=lambda]]