Marisol is designing a system to detect when the door to her room is opened. She has observed that the magnetic field in the vicinity of the door is perpendicular to the door when it is closed and has a magnitude of about B = 5.50 × 10 − 5 T. B=5.50×10−5 T. Knowing Faraday's law, Marisol uses electromagnetic induction as the basis of her alarm. She wraps a single loop of wire around the perimeter of her door and connects it to a voltmeter that can detect an emf as small as V min = 1.00 × 10 − 6 V. Vmin=1.00×10−6 V. The voltmeter is configured to take a time‑averaged reading and will trigger the alarm if the average emf over a certain period of time exceeds the threshold voltage V min . Vmin. What is the minimum time interval t min tmin required for someone to open Marisol’s door θ = 34.0 ∘ , θ=34.0∘, starting from the closed position, without the average induced emf over that time interval exceeding the threshold? The dimensions of the door are W = 0.895 m W=0.895 m by H = 2.15 m.

To understand the behavior of the electric field at the surface of a conductor, and its relationship to surface charge on the conductor. a conductor is placed in an external electrostatic field. the external field is uniform before the conductor is placed within it. the conductor is completely isolated from any source of current or charge. part a: which of the following describes the electric field inside this conductor? it is in the same direction as the original external field.it is in the opposite direction from that of the original external field.it has a direction determined entirely by the charge on its surface.it is always zero. part b: the charge density inside the conductor is: 0non-zero; but uniformnon-zero; non-uniforminfinite part c: assume that at some point just outside the surface of the conductor, the electric field has magnitude e and is directed toward the surface of the conductor. what is the charge density η on the surface of the conductor at that point? express your answer in terms of e and ϵ0