# Questions Using Planck's Constant

Part 1

An electron microscope operates with a beam of electrons, each of which has an energy of 20 KeV. Use the uncertainty principle in the form delta(x)delta(p) (greater or equal to) h/2 to find the smallest size that such a device could resolve. Planck's constant is 1.0552 × 10^-34 J · s. Answer in units of pm.

Part 2

What must the energy of each neutron in a beam of neutrons be in order to resolve the same size object?

Answer in units of eV.

Part 3

A beam of neutrons with a kinetic energy of 0.0002 eV falls on a slit of width 0.0001 m.

The Planck's constant is 6.63 × 10 ^-34 J · S.

What will be the angular spread of the beam after it passes through the slit?

Answer in units of radian.

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#### Solution Preview

Hi C!

Here are the solutions to this problems set.

However, I must say I'm confused regarding the way the first problem is to be solved. It is stated that it should be solved using the uncertainty principle, while a more reasonable approach is the ...

#### Solution Summary

This solution provides step by step calculations for various questions involving Planck's constant.