No links, rubbish answers etc will mark brainliest thx

Hi can someone help me with this sum pls​

Which type of current is produced by a wire breaking magnetic field lines and changing the polarity? a. alternating b. direct c. straight d. alternating and direct

Which property is expressed in distance units? o a. period o b. wavelength o c. speed o d. frequency

Acircular ring of charge with radius b has total charge q uniformly distributed around it. what is the magnitude of the electric field at the center of the ring? 0 keq/b2 keq2/b2 keq2/b none of these answers