In comparing first magnitude Deneb with second magnitude Polaris, we find that
A) Polaris is in reality much more luminous.
B) Deneb must be much hotter than Polaris.
C) Deneb appears 2.5 times brighter to us than does Polaris.
D) Polaris is really 100 times brighter than nearby Deneb.
E) Deneb is really much closer than Polaris.
C
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Equilibrium: In the figure, a uniform ladder of weight 200 N and length 10 m leans against a perfectly smooth wall. A firefighter of weight 600 N climbs a distance x up the ladder. The coefficient of static friction between the ladder and the floor is 0.50. What is the maximum value of x for which the ladder will not slip?
A. 3.9 m B. 5.0 m C. 6.0 m D. 6.3 m E. 8.4 m
The radio radiation emitted by a radio lobe is mainly synchrotron radiation
a. True b. False Indicate whether the statement is true or false
Force on a Wire: A rigid rectangular loop, measuring 0.30 m by 0.40 m, carries a current of 9.9 A, as shown in the figure. A uniform external magnetic field of magnitude 1.8 T in the -x direction is present. Segment CD is in the xz-plane and forms a 19° angle with the z-axis, as shown. What is the y component of the magnetic force on segment AB of the loop?
A. +5.1 N B. -5.1 N C. +1.7 N D. -1.7 N E. 0.0 N
Light of wavelength 418 nm is incident on a slit of width 0.35 mm, and a diffraction pattern is produced on a screen that is 2.4 m from the slit. What is the distance of the second dark fringe from the center of the bright fringe? (1 nm = 10?9 m)
a. 2.9E–7 m b. 5.7E–3 m c. 1.6E–3 m d. 1.4E–6 m e. 1.1E–6 m