When a light bulb is turned on, its resistance increases until it reaches operating temperature. What happens to the current in the bulb as it is warming up?
a. It stays constant.
b. It increases.
c. It decreases.
d. It increases at first and then decreases.
c
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An oscillating system has a small amount of damping. It is observed that in the course of 20.0 s the amplitude has decreased from A to A/2. What additional time is required for the amplitude to decrease to A/10?
What will be an ideal response?
A hydrogen atom is excited to the n = 11 level. Its decay to the n = 7 level is detected in a photographic plate. What is the wavelength of the light photographed? (c = 3.00 × 108 m/s, 1 eV = 1.60 × 10-19 J, h = 6.626 × 10-34 J ? s)
A) 7,510 nm B) 4,670 nm C) 12,400 nm D) 4,380 nm
Consider two diffraction gratings; one has 4000 lines per cm and the other one has 6000 lines per cm. Make a statement comparing the dispersion of the two gratings
A) The 4000-line grating produces the greater dispersion. B) The 6000-line grating produces the greater dispersion. C) Both gratings produce the same dispersion, but the orders are sharper for the 4000-line grating. D) Both gratings produce the same dispersion, but the orders are sharper for the 6000-line grating.
How did scientists first prove that light had a finite speed?
a. By measuring how long it takes for a second observer to be seen uncovering a lantern on a distant mountain in response to the first observer uncovering a lantern. b. By measuring how long it took to see lightning during a thunderstorm. c. By measuring how fast a notched wheel must rotate for light passing through one notch to be reflected from a distant mirror back through the next notch. d. By measuring how fast a multi-faced mirror must rotate for light reflected from one mirror face to be reflected from a distant mirror to reflect back from the next face. e. By measuring how the revolution of the moons of Jupiter appears longer when they are farther from Earth.