Dr. Vikram Panchal
Institute Of Chemistry
Worksheet: Heisenberg’s uncertainty principle, De-Broglie’s
wavelength based questions:
(1.) Calculate the wavelength of a soft ball of mass of 100g travelling at a velocity of 35 ms-1.
(2.) If uncertainties in the measurement of position and momentum are equal, calculate the
uncertainty in the measurement of velocity.
(3.) Calculate the uncertainty in the velocity of wagon of mass 2000kg whose position is known to
an accuracy of 10m.
(4.) Calculate the wavelength of an electron with mass 9.1 x 10-31 kg and kinetic energy 3.0 x 10-25
J. (Given: K.E.=1/2mv2)
(5.) A rubber ball has a mass of 100 g and can move with a speed of 50 ms -1. If speed can be
measured within accuracy of 1%, calculate the uncertainty in the position.
(6.) Calculate the wavelength of an electron moving with a velocity of 2.05 x 107 ms-1.
(7.) Dual behavior of matter proposed by De-Broglie led to the discovery of electron microscope
often used for the highly magnified images of biological molecules and other type of material. If
the velocity of the electron in this microscope is 1.6 x 106 ms-1, calculate the De-Broglie
wavelength associated with this electron.
(8.) A body of mass ‘x’ kg is moving with a velocity of 100 ms-1. Its De-Broglie wavelength is 6.62
x 10-35 m. Hence, x is __________. (h=6.62 x 10-34 Js)
(9.) The uncertainty in the position of an electron (mass=9.1 x 10-31 kg) moving with a velocity of
3.0 x104 cms-1 accurate up to 0.011% will be ________.
(10.) A particle having a mass of 1.0 mg has a velocity of 3600 km/h. Calculate the wavelength of
the particle.
(11.) Calculate the frequency and wave number of radiation with wavelength 480 nm.
(12.) If uncertainty in the position of an electron is zero, the uncertainty in its momentum would be
________.
(13.) The uncertainty in the position of a moving bullet of mass 10gm is 10-5. Calculate the
uncertainty in its velocity.
(14.) According to Heisenberg’s uncertainty principle, the product of uncertainties in position and
velocities for an electron of mass 9.1x10-31kg is _________.
(15.) What is the De-Broglie wavelength associated with the hydrogen electron in its third orbit?
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