A. 若高斯面上的电场强度处处为零,则该面内必定没有电荷; B. 若高斯面内没有电荷,则该面上的电场强度必定处处为零; C. 若高斯面上的电场强度处处不为零,则该面内必定有电荷; D. 若高斯面内有净电荷,则该面上的电场强度通量必不为零。
A. σ/ε0 B. σ/2ε0 C. σ/4ε0 D. σ/8ε0
A. Have a drink. B. Meet a friend. C. Visit a company. D. Write a report.
A. On television. B. From a newspaper. C. Through the Internet. D. Over the radio.
A. It snowed heavily. B. It rained hard. C. The wind was strong. D. The fog was thick