What is the frequency of 20-mm microwaves? (c = 3.0 × 108 m/s)
A) 100 MHz
B) 400 MHz
C) 15 GHz
D) 73 GHz
C
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A European sports car dealer claims that his product will accelerate at a constant rate from rest to a speed of 100 km/hr in 9.00 s. What distance will the sports car travel during the 9.00 s acceleration period?
Energy Density: A 4.4 × 1014 Hz laser emits a 2.1 ?s pulse that is 5.0 mm in diameter. The energy density in the beam is 0.24 J/m3. How many wavelengths are there in the length of the beam? (c = 3.0 × 108 m/s, ?0 = 4? × 10-7 T ? m/A, ?0 = 8.85 × 10-12 C2/N ? m2)
A. 9.2 × 108 B. 2.8 × 109 C. 2.8 × 108 D. 9.2 × 109 E. 2.8 × 1010
Resistance and Resistivity: The figure shows a graph of the resistance of a wire as a function of its length. What physical quantities does the slope of this graph represent?
A. the cross-sectional area of the wire B. the resistivity of the material of which the wire is made C. the product of the resistivity and the cross-sectional area of the wire D. the resistivity of the material divided by the cross-sectional area of the wire E. the reciprocal of the resistivity of the material
Two sounds of the same intensity are added together. The intensity of the resulting sound is how many decibels greater than the intensity of one of the original sounds? The resulting sound
1.will have twice the decibel level as one of the original sounds. 2.will have the same decibel level as one of the original sounds. 3.will be two decibels higher than the original sound. 4.will be three decibels higher than the original sound.