PPSC Lecturer of Physics Online Test 35 Past Papers

Which of the following is essential for laser action to occur between two energy levels of an atom?

The purpose of the mirrors at the ends of a helium-neon laser is:

The spectrum of a black body is:

Which principle is in effect when a ship displaces ocean water?

A gas behaves as an ideal gas at:

The force that moves a rocket or a plane forward is called:

Fluid mechanics is the study of how fluids move and the..............on them:

Newton’s law of cooling is a special case of:

When air moves an airfoil, ................ is generated:

Photons in a laser beam are produced by:

Birds, planes and boats are streamlined to reduce:

Any substance that can flow is a:

The design of an airfoil uses:

Which of the following is essential for laser action to occur between two energy levels of an atom?

The study of the deformation and flow of matter, primary in the liquid state is called:

With increase in temperature, the angle of contact of liquid:

The colour of a star is an indication of its:

In flow through a straight, smooth, pipe, the critical Reynolds number for transition to turbulence is generally taken to be:

Which force pushes up a body in a fluid?

In a helium-neon laser, the laser light arises from a transition from a state to a state:

Population inversion is important for the generation of a laser beam because it assures that:

A metastable state is important for the generation of a laser beam because it assures that:

Minor losses through valves, fittings, bends, etc., are modelled as proportional to:

What is the absorption power of perfect black body?

What is measured by a Bolometer?