To observe interference in thin films with a light of wavelength λ, the thickness of the film:

• A) Undetermined
• B) Should be of the order of λ
• C) Should be much smaller than λ
• D) Should be much larger than λ

Maxwell’s equations predict that the speed of light in free space is

• A) a function of the distance from the source
• B) independent of frequency
• C) a decreasing function of frequency
• D) an increasing function of frequency

According to the Second Law of Thermodynamics, what is the maximum efficiency a nuclear reactor with a core temperature of 300 K and rejecting heat at 30 K can achieve?

• A) 0.9
• B) 0.824
• C) 0.2
• D) 0.47

Which of the following best describes the nature of light?

• A) Light is electromagnetic wave.
• B) Light is composed of electrons only
• C) Light is composed of aether particles.
• D) Light is a longitudnal wave.

The special theory of relativity is based on:

• A) Three postulates
• B) Two postulates
• C) Five postulates
• D) Four postulates

If a glass of water is placed in the open atmosphere and no heat is exchanged between them, the state of the system is:

• A) Thermal expansion.
• B) Thermal resistance.
• C) Thermal difference.
• D) Thermal equilibrium.

For holography we use a beam of:

• A) LASER
• B) X – rays
• C) ß – rays
• D) α – rays

How does a Polaroid filter work to polarize light?

• A) By selectively transmitting light waves vibrating in a specific direction.
• B) By reversing the direction of light waves passing through it.
• C) By absorbing all colors of light except the desired color.
• D) By amplifying the intensity of light waves passing through it.

What is the unit of the Stefan-Boltzmann constant (σ)?

• A) Joule/sec
• B) m/s
• C) Watt/(m2⋅K4)
• D) N⋅m2/kg2

The efficiency of a heat engine is always less than one because:

• A) The temperature of the reservoirs is constant.
• B) Some work is always lost as heat.
• C) Heat is converted entirely into work.
• D) Some heat is always lost to the surroundings.

Why does the temperature of boiling water remain constant (at 100o C) despite continuous heating?

• A) Heat changes the phase of water.
• B) Heat lowers the surrounding pressure.
• C) Heat escapes rapidly.
• D) Heat increases the volume of water.

Which of the following waves do not travel at speed of light?

• A) Radio waves
• B) Sound waves
• C) Heat waves
• D) X – rays

A balloon is filled with cold air and placed in a warm room. It is NOT in thermal equilibrium with the air of the room until:

• A) It stops expanding
• B) It rises to the ceiling
• C) It sinks to the floor
• D) It starts to contract

The distance between two adjacent bright fringes is:

• A) d/λL
• B) λd /L
• C) λL/d
• D) L/λd

The wavelength of radiation at 1000 kelvin for a black body is:

• A) 2.9×10-3 m
• B) 2.9×10-3 cm
• C) 2.9×10-6 m
• D) 2.9×10-6 cm

Polarization experiments provide evidence that light is:

• A) nearly monochromatic
• B) some type of wave
• C) a longitudinal wave
• D) a transverse wave

A heat of transformation of a substance is:

• A) The same as the heat capacity
• B) The energy absorbed as heat during a phase transformation
• C) The energy per unit mass absorbed as heat during a phase transformation
• D) The same as the specific heat

Two events occur 100m apart with an intervening time interval of 0.60µs.The speed of a reference frame in which they occur at the same coordinate is:

• A) 0.25c
• B) 1.1c
• C) 0.56c
• D) 0

The two metallic strips that constitute some thermostats must di?er in:

• A) Mass
• B) Rate at which they conduct heat
• C) Coe?cient of linear expansion
• D) Thickness Length

The reason there are two slits, rather than one, in a Young’s experiment is:

• A) to increase the intensity
• B) one slit is for frequency, the other for wavelength
• C) to create a path length difference
• D) one slit is for Electric fields , the other is for Magnetic fields