Answer:1) d - it's always zero
2) a- 0
3) eta = - epsilon_0E
Step-by-step explanation:
1) When a conductor is placed in an external electric field, the charges will accumulate to the two ends of the conductor depending on the direction of the field. As a result of this charge accumulation, the inside field develops and cancels with the outside field. Leaving the net field is always zero
2) we already know from answer 1, that there is a zero net electric field inside a conductor; therefore, if you surround any internal point with a Gaussian surface, there will be no flow at any point on this surface, and hence the surface will enclose zero net charge. Therefore, the charge density must be zero everywhere inside the conductor.
3) the charge density will be given as:
eta = - epsilon_0E