IB Physics 12.2

An electron of mass m has an uncertainty in its position r. What is the uncertainty in the speed of this electron?

Which of the following, observed during a radioactive-decay experiment, provide evidence for the existence of nuclear energy levels?

I.   The spectrum of alpha particle energies

II.  The spectrum of beta particle energies 

III. The spectrum of gamma ray energies 

• I and II only

• I and III only 

• II and III only 

• I, II and III

Which of the following experiments provides evidence for the existence of matter waves?

• Scattering of alpha particles

• Electron diffraction

• Gamma decay

• Photoelectric effect

The graphs show the variation with distance x of the square of the amplitude Ψ² of the wave function of a particle. Which graph corresponds to a particle with the largest uncertainty in momentum?

• 
• 
• 
• 

Deviations from Rutherford scattering are detected in experiments carried out at high energies. What can be deduced from these deviations?

• The impact parameter of the collision

• The existence of a force different from electrostatic repulsion

• The size of alpha particles

• The electric field inside the nucleus

A pure sample of mass m of a radioactive substance with half-life T_1/2 has an initial activity A₀.

 

What are the half-life and the initial activity of a pure sample of mass 2m of the same radioactive substance?

• A

• B

• C

• D

Nuclear density...

• is constant because the volume of a nucleus is proportional to its nucleon number.

• is constant because the volume of a nucleus is proportional to its proton number.

• depends on the nucleon number of the nucleus.

• depends on the proton number of the nucleus.

When monochromatic light is incident on a metallic surface, electrons are emitted from the surface. The following changes are considered.

I.    Increase the intensity of the incident light

II.   Increase the frequency of light

III.  Decrease the work function of the surface

Which changes will result in electrons of greater energy being emitted from the surface?

• I and II only

• I and III only

• II and III only

• I, II and III

Electron capture can be represented by the equation

p + e^– → X + Y.

What are X and Y?

• X: proton

  Y: positron

• X: electron

  Y: positron

• X: neutron

  Y: electron antineutrino

• X: neutron

  Y: electron neutrino

Two samples X and Y of different radioactive isotopes have the same initial activity. Sample X has twice the number of atoms as sample Y. The half-life of X is T. What is the half-life of Y?

• 2T

• T