A transformer is designed to step down the 120 V line voltage to 9 V. If there are 400 turns on the input coil, how many turns should there be on the output coil?
30
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A muon formed high in the Earth's atmosphere travels at a speed 0.870c for a distance of 4.00 km before it decays. What is the muon's lifetime as measured in its reference frame?
a. 3.1E–5 s b. 7.6E–6 s c. 1.5E–5 s d. 5.1E–5 s e. 4.3E–5 s
Three long wires parallel to the x axis carry currents as shown. If I = 20 A, what is the magnitude of the magnetic field at the origin?
a.
37 ?T
b.
28 ?T
c.
19 ?T
d.
47 ?T
e.
58 ?T
Parallel-Plate Capacitor: An ideal air-filled parallel-plate capacitor consists of plates that are 1.0 mm apart and have an area of 1.5 × 10-4 m2. The capacitor is connected to a 12-V potential source (battery). (?0 = 8.85 × 10-12 C2/N ? m2)(a) What is the capacitance of this capacitor?(b) How much charge is on each of its plates?(c) What is the strength of the electric field between the plates?
What will be an ideal response?
Which of the following statements describes a true observation that represents strong physical evidence that magnetic poles are not the same as electric charges? Select all answers that are both physically true and represent relevant evidence. (To select multiple answers using the back of the book, point to answers with multiple fingers.)
A. We describe magnetic poles as being north and south but charges as being positive or negative. B. A magnet does not exert force on a motionless charged particle, but another charged particle will. C. A magnet exerts force in a different direction on a motionless charged particle than a charged particle does. D. Magnetic fields are measured in teslas, but electric fields are measured in N/C. E. No one has seen an isolated magnetic pole. F. What do you mean? At the deepest level, electric charges and magnetic poles really are the same thing!