Second Year Physics Chapter 19 Online MCQ Test for 2nd Year Physics Chapter 19 Dawn of Modern Physics Preparation

Platinum wire becomes white at a temperature of.

• 1600^oC A
• 1300^oC B
• 1100^oC C
• 900^oC D

When platinum is heated is become dull red at:

• 900°C A
• 500°C B
• 800°C C
• 1100°C D

The concept of direction is purely

• Relative A
• Absolute B
• Relative to the motion C
• None of these D

A positron is an anti particle of.

• Proton A
• Electron B
• Neutron C
• Photon D

When platinum is it becomes orange at.

• 500^oC A
• 900^oC B
• 1100^oC C
• 1300^oC D

Pair production occurs only when energy of photon is at least equal in:

• 1.02keV A
• 1.02 eV B
• 1.02 MeV C
• 1.02 GeV D

All motions are

• Absolute A
• Uniform B
• Relative C
• Variable D

• Wien's constant A
• Planck's constant B
• Davison constant C
• Lumber's constant D

A perfect absorber must also be perfect

• Cavity A
• Sources of radiation B
• Radiator C
• None of these D

The value of Stefan is constant is:

• 4.57 x 10^-8 m²k² A
• 5.67 x10^-8 wm^-2k^-4 B
• 6.67x 10^-11 wm²k⁴ C
• 7.45 x  10^-9 m² wk³ D

We can never accurately describes all aspects of sbatomic particles simulatanously. It is correct according to:

• Uncertainity Priciple A
• De-broglie Theory B
• Einstin Theory C
• Photo electric effect D

When the K.E. of photoelectric is zero, the frequency of incident photon is.

• Less than A
• greater than B
• Equal to C
• Much greater D

The energy of the photon of wavelength 500 nm is.

• 3.10 eV A
• 2.49 eV B
• 1.77 eV C
• 1.52 eV D

The uncertainty principle was given by

• De-Broglie A
• Heisenberg B
• Einstein C
• Max Planck D

Eintein's Photoelectric equation is E_k= hf -∅ in this equation E₁, refers to:

• K.E of al the emited electrons A
• Mean K.E of emited electrons B
• Maximum K.E of emited electrons C
• Minimum K.E of emited electrons D

De-Broglie waves are associated with

• Moving charged particles only A
• Moving neutral particles only B
• All moving particles C
• All parties whether in motion or at rest D

Potassium Cathodes in photocell emit electrons for a light.

• Visible A
• Infra red B
• Ultra violet C
• X rays D