समांतर प्लेट संधारित्र (parallel plate capacitor) वाले एक रेखीय, एकल-उत्तेजित विद्युत क्षेत्र प्रणाली में, सह-ऊर्जा घनत्व (co-energy density) को विद्युत क्षेत्र की तीव्रता E और विद्युतशीलता ε0 के पदों में निम्नलिखित में से किसके द्वारा व्यक्त किया जाता है?

Which of the following statements are correct regarding electrostatic properties of conductors? A. Inside a conductor, the electrostatic field is zero. B. Electric field at the surface of a charged conductor does not depend on its surface charge density. C. The interior of a charged conductor can have no excess charge in static conditions. D. At the surface of a charged conductor, the electrostatic field must be normal to the surface at every point. E. The electrostatic potential is zero everywhere inside a charged conductor. Choose the correct answer:

What type of electric charge is acquired by a glass rod when it is rubbed with a silk cloth?