Chinese preparation relies heavily on problem sets like "300 Physics Problems" (often specific to Mechanics or EM).

cap I equals d q over d t end-fraction equals the fraction with numerator lambda open paren 2 pi cap R close paren and denominator the fraction with numerator 2 pi and denominator omega end-fraction end-fraction equals lambda cap R omega The magnetic field at the center is:

While not a direct PDF of CPhO, many books by authors like or collections edited by Lim Yung-kuo (specifically "Problems and Solutions on Mechanics/Electromagnetism") are staples in the Chinese training system. Digital versions of these are often available through academic repositories. 3. Online Competitive Physics Communities