The electrons in a beam are moving at 18 m/s. (melectron = 9.11 × 10-31 kg, h = 6.626 × 10-34 J ? s)
(a) What is its de Broglie wavelength these electrons?
(b) If the electron beam falls normally on a diffraction grating, what would have to be the spacing between slits in the grating to give a first-order maximum at an angle of 30° with the normal to the grating?
(a) 40 μm (b) 81 μm
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Diagram 6-2 illustrates a light source, a gas cloud, and three different lines of sight. Along which line of sight would an observer see an emission spectrum?
a.
1
b.
2
c.
3
d.
2 and 3
e.
none of them
A mobile is made of identical objects of mass m suspended so that the lowest row has one object, the row above two objects, and the row above three objects. All the strings are at 45° angles. What is the average tension in the strings connecting the highest row to the ceiling?
A.
B.
C.
D.
E.
The distance of the Earth from the Sun is 93,000,000 miles. If there are 3.15 × 10^7 s in one year, find the speed of the Earth in its orbit about the Sun
a. 9.28 miles/s c. 27.9 miles/s b. 18.6 miles/s d. 37.2 miles/s
For very small objects at very low speeds, the drag force is directly proportional to the magnitude of the velocity. The proportionality constant depends on
A) the viscosity of the fluid. B) the size of the object. C) the shape of the object. D) all of the above choices. E) none of the above choices.