Calculate the critical current for a wire of lead having a diameter of 1mm at 4.2 K. Calculate temperature for lead is 7.18 K and Hc = 6.5×104 A/m. Critical field is 42.758×103 A/m.

• A. 3.5593 A
• B. 27.3 A
• C. 46.67 A
• D. 134.26 A