Option B1 Formative Printed Name:______
Date:______Period:____
This is a formative assessment, which means that it is practice. In order to get used to the format for the summative assessment you will do later to actually demonstrate your proficiency with this material, adhere to the following:
●Show all your work including formulas and substitutions because partial credit will be awarded for legitimate work even though the answer or calculations may be wrong.
●Place answers in the space provided or they will not be counted.
(1) In the picture to the right label the cutoff voltage, and explain how it is determined.
(2) Explain the concept of the cutoff frequency.
(3) In the mathematical formulation of the photoelectric effect, hf = f + eV, describe what each part of the equation represents, in terms of work and energy.
A photosensitive metal has a work function of 3.65 eV.
(4) Find the minimum frequency of light needed to free an electron from its surface. (4) ______
(5) Find the maximum kinetic energy of an electron freed by a photon having a frequency of 2.48´1015 Hz. (5) ______
(6) Find the cutoff voltage for the photons of (5). (6) ______
An electron is accelerated from rest through a potential difference of 725 V.
(7) What is its expected de Broglie wavelength? (7) ______
(8) On the back of this sheet show that the allowed kinetic energies of an electron that resonates in a box of length L is given by EK = n2h2/[8mL2]. Include wave sketches.
An electron and a jet fighter have equal speeds of 585 m/s, accurate to within ±0.0125%.
(9) What is the minimum uncertainty in the position of the electron?
(9) ______
(10) What is the minimum uncertainty in the position of the 645-kg jet fighter?
(10) ______
An electron in an excited state has a lifetime of 1.45´10-8 seconds before it deexcites.
(11) What is the minimum uncertainty in the energy of the photon emitted on de-excitation? (11) ______
(12) What is the magnitude in the broadening of the frequency of the spectral line?
(12) ______