At 1 kHz, the skin depth in copper is 2 mm. Determine the a.c. resistance at 500 kHz and at 10 MHz of 20 cm lengths of copper conductors having the following cross sections:
(a) round section 20 mm2
(b) square section 20 mm2
(c) rectangular section 1 mm × 20 mm
Take the conductivity of copper as 5.8 × 107 Sm-1
Comment on the results.