Matter Waves: 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?

Fill in the blank(s) with the appropriate word(s).


(a) 40 ?m (b) 81 ?m

Physics & Space Science

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The ________ hemisphere of Mars is lower, smoother, and younger than the other one

Fill in the blank(s) with correct word

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What age does radiometric dating give for Moon rocks and meteorites?

a. zero b. about 6000 years c. about 4 million years d. about 4 billion years e. about 14 billion years

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Pulsars can be created by neutron stars or black holes

a. True b. False Indicate whether the statement is true or false

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A particle (q = +5.0 ?C) is released from rest when it is 2.0 m from a charged particle which is held at rest. After the positively charged particle has moved 1.0 m toward the fixed particle, it has a kinetic energy of 50 mJ. What is the charge on the fixed particle?

A. ?2.2 ?C B. +6.7 ?C C. ?2.7 ?C D. +8.0 ?C E. ?1.1 ?C

Physics & Space Science