Chapter 39: Q.46 - Excercises And Problems (page 1118)

A small speck of dust with mass 1.0×10-13ghas fallen into the hole shown in FIGURE P39.46 and appears to be at rest. According to the uncertainty principle, could this particle have enough energy to get out of the hole? If not, what is the deepest hole of this width from which it would have a good chance to escape?

Short Answer

Expert verified

The value of ΔEless than the value of V, so the particle will have enough energy to get out the hole. The deepest hole is 0.17×10-28mfor which, particle have a good chance to escape from the hole..

Step by step solution

01

Given Information

Dust mass =1.0×10-13g

Width of the box Δx=10μm

=0μm1m106μm

The uncertainity principle is given by,

Δxpxh2

Where, Δxis measurement of position, Δpxis measurement of the momentum of the particle and his plank's constant.

02

Step 2:Solution

A1=3.3×10-23lg/5-1

The energy and momenturm relation of particle is egven by

ΔT=Δn1=

AlH is uncertainity in measurem ent of energy of particle.

Applying values,

ΔH-1.65+10-3J

The height of potertial barrier is gven by,

V=mnh

Where v is height af potental barrier, th is mass of particle, Bts acceleratien due to graify

Apply ing values,

localid="1650898379149" V=1.0×10-13R9xms-3(1ma)=1.0×10-13e9Nms-2(1μm)1m1mV=0×8×10-2I

Hence, localid="1650898382670" AEcVthe oarticle all not have enough energy to get out the hole

To find the masimum height, ursig the formula.

localid="1650898390302" mtH=AEI localid="1650898386256" AIshendbegreaterorc्यeal

localid="1650898394321" =AUπt

Apphing values,

localid="1650898410368" =0.17×10-23m

Concluiton: The value of localid="1650898415592" Eless than the value of localid="1650898452767" V2so the particle aill have enough energy to get eut the hole. The deepest hole is localid="1650898424914" 0.17×10-2"a for which, particle have a good chance to escape from the hole.

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Most popular questions from this chapter

Physicists use laser beams to create an atom trap in which atoms are confined within a spherical region of space with a diameter of about 1mm. The scientists have been able to cool the atoms in an atom trap to a temperature of approximately 1nK, which is extremely close to absolute zero, but it would be interesting to know if this temperature is close to any limit set by quantum physics. We can explore this issue with a onedimensional model of a sodium atom in a 1.0-mm-long box.

a. Estimate the smallest range of speeds you might find for a sodium atom in this box.

b. Even if we do our best to bring a group of sodium atoms to rest, individual atoms will have speeds within the range you found in part a. Because there's a distribution of speeds, suppose we estimate that the root-mean-square speed vrmsof the atoms in the trap is half the value you found in part a. Use this vrmsto estimate the temperature of the atoms when they've been cooled to the limit set by the uncertainty principle.

The probability density for finding a particle at position xis

px=a1-xb1-x-1mmx<0mm0mmx1mm

and zero elsewhere

The probability density for an electron that has passed through an experimental apparatus. If 1.0×106electrons are used, what is the expected number that will land in alocalid="1649312933417" 0.010mmwide strip atlocalid="1649312941736" (a)x=0.000mmand localid="1649312949893" (b)2.000mm?

What is the smallest one-dimensional box in which you can confine an electron if you want to know for certain that the electron's speed is no more than 10m/s ?

Heavy nuclei often undergo alpha decay in which they emit an alpha particle (i.e., a helium nucleus). Alpha particles are so tightly bound together that it's reasonable to think of an alpha particle as a single unit within the nucleus from which it is emitted.

a. AU238nucleus, which decays by alpha emission, is 15fm in diameter. Model an alpha particle within a U238nucleus as being in a one-dimensional box. What is the maximum speed an alpha particle is likely to have?

b. The probability that a nucleus will undergo alpha decay is proportional to the frequency with which the alpha particle reflects from the walls of the nucleus. What is that frequency (reflections/s) for a maximum-speed alpha particle within a U238nucleus?

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