Exam 28: Quantum Physics

A photocathode whose work function is 2.5 eV is illuminated with white light that has a continuous wavelength band from 360 nm to 700 nm.The stopping potential for this white light illumination is closest to:

Upon being struck by 240 nm photons,a material ejects electrons with a maximum kinetic energy of 2.58 eV.What is the work function of this material?

An electron is accelerated from rest through a potential difference.After acceleration the electron has a wavelength of 880 nm.What is the potential difference responsible for the acceleration of the electron?

A molecule of roughly spherical shape has a mass of 1.80 × 10^-25 kg and a diameter of 0.6 nm.The uncertainty in the measured position of the molecule is equal to the molecular diameter.The minimum speed of the molecule is closest to:

If the threshold frequency of a certain metal is 2.0 × 10¹⁴ Hz,light of frequency 1.9 x 10¹⁴ Hz will not be able to dislodge any photoelectrons from this metal.

Electrons emerge from an electron gun with a speed of 2.0 × 10⁶ m/s.They are made to pass through a double-slit apparatus.Interference fringes with spacing of 2.7 mm are detected on a screen far from the double slit.What would the fringe spacing be if the electrons were replaced by neutrons with the same speed?

An electron's de Broglie wavelength is 4.8 μm.What is its speed?

Find the wavelength (in nm)of a 6.32 eV photon.

You want to confine an electron and you want to know for certain that the electron's speed is no more than 66 m/s.What is the length of the smallest box in which you can do this?

Monochromatic light is incident on a metal surface.The ejected electrons give rise to a current in the circuit shown.The maximum energy of the ejected electrons is determined by applying a reverse ("stopping")potential,sufficient to reduce the current in the ammeter to zero. If the intensity of the incident light is increased,how will the required stopping potential change?

A 10 g bouncy ball is confined in a 8.3 cm long box.What is its minimum energy?

An electron is confined in a one-dimensional box.Two adjacent allowed energies of the electron are 2.8 × 10^-19 J and 3.5 × 10^-19 J.What is the length of the box?

Illuminating a particular metal surface with a helium-neon laser results in the emission of photoelectrons.Will the kinetic energy of the photoelectrons increase if you increase the laser's power? Support your answer.

A 84 kW AM radio station broadcasts at 1000 KHz.How many photons are emitted each second by the transmitting antenna?

An electron has the same de Broglie wavelength as a 390 nm photon.The speed of the electron is closest to:

A light beam from a 2.1 mW He-Ne laser has wavelength of 633 nm.How many photons does the laser emit in one second?

Electrons with a speed of 2.1 × 10⁶ m/s are directed towards a 1.0 μm wide slit.An electron detector is placed 1.0 m behind the slit.How wide is the electron diffraction pattern on the detector?

What is the velocity of an electron with a de Broglie wavelength of 4.32 μm?

Electrons are sent through a double-slit apparatus,and an interference pattern is observed.If protons are sent through the same apparatus with the same speed as that of the electrons,the distance between the fringes would be

A photon of blue light