An opaque horizontal plate is insulated on the backside. The plate irradiation is 2500 W/m^2 of which 500 W/m^2 is reflected. The plate temperature is 227ºC and has an emissive power of 1200 W/m^2. Air at 127ºC and with a convective heat transfer coefficient of 12 W/m^2 K flows over the plate. Determine (a) emissivity, absorptivity, and radiosity of the plate and (b) the net heat transfer per unit area.
From the problem statement, the reflectivity is
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Electromagnetic induction occurs in a coil when there is a change in
A) electric field intensity in the coil. B) magnetic field intensity in the coil. C) electromagnetic polarity. D) none of the above
The speed of FM waves will be observed to be c = 2.9979 × 10^8 m/s when the antenna emitting the waves is
a. at rest relative to the receiving antenna. b. moving to the right of the detecting antenna at 0.5 c. c. moving to the left of the detecting antenna at 0.5 c. d. moving as described in (a), (b) or (c) above. e. moving at 2.9979 × 10^8 m/s.
Characteristics of Waves: An earthquake generates three kinds of waves: surface waves (L-waves), which are the slowest and weakest, shear (S) waves, which are transverse waves and carry most of the energy, and pressure (P) waves, which are longitudinal waves and are the fastest. The speed of P waves is approximately 7 km/s, and that of S waves is about 4 km/s. People do not generally feel the P waves, but animals seem to be sensitive to them. If a person reports that her dog started barking 20 seconds "before the earthquake," then approximately how far was the origin of the earthquake?
A. 100 km B. 200 km C. 300 km D. 400 km E. 500 km
The coil of a generator has 50 loops and a cross-sectional area of 0.25 m2. What is the maximum emf generated by this generator if it is spinning with an angular velocity of 4.0 rad/s in a 2.0 T magnetic field?
A) 100. V B) 50. V C) 400. V D) 75. V E) 0. V