The BNM/LCIE has developed several sets of AC standard resistors characterized by comparison to a calculable resistor in the frequency range 100 Hz - 20 kHz. The studies are going on in the frequency range 20 kHz - 1 MHz.
The resistors are of two terminals type for the values between 100 ohm and 2 M ohm and of four terminals type between 100 Û and 30 mÛ.
They have been realized mainly in thin film technology excepted for the high values for which commercial standards have been purchased.
The time constants observed are in the range of some hundreds picoseconds for the low values of resistance up to some hundreds nanoseconds for the hig values.
These resistors will be modified in such a way that they should be used as primary standards and travelling standards with adequate uncertainties and travelling characteristics.