Room temperature is about 20 degrees on the:

• A) Kelvin scale
• B) Absolute scale
• C) Celsius scale
• D) Fahrenheit scale

If two objects are in thermal equilibrium with each other:

• A) They can not be undergoing an elastic collision
• B) They can not be moving
• C) They can not be at di?erent temperatures
• D) They can not have di?erent pressures

The equation for time dilation is given by:

• A) $$\Delta t = \sqrt \gamma {\text{ }}\Delta t'$$
• B) $$\Delta t' = \frac{{\Delta t}}{\gamma }$$
• C) $$\Delta t = \frac{{\Delta t'}}{\gamma }$$
• D) $$\Delta t' = \gamma {\text{ }}\Delta t$$

It is more di?cult to measure the coe?cient of volume expansion of a liquid than that of a solid because:

• A) No relation exists between linear and volume expansion coe?cients
• B) A liquid tends to evaporate
• C) A liquid expands too much when heated
• D) The containing evessel also xpands

Two sources of light are said to be coherent if the waves produced by them have the same:

• A) Amplitude
• B) Wavelength and constant phase difference
• C) Wavelength and amplitude
• D) Wavelength

In some movies, you sometimes see an actor looking in a mirror and you can see his face in the mirror. During the filming of this scene, what does the actor see in the mirror?

• A) The movie camera
• B) The director's face
• C) His face
• D) Your face

The temperature of the ice throughout the melting process when it is continuously heated by a small gas flame is:

• A) Remains constant initially and then increases.
• B) Increases until it turns into liquid water.
• C) Rises gradually.
• D) Remains constant.

When an object reflects or emits light equally across all wavelengths, it appear _____ to our eyes?

• A) Black
• B) Red
• C) Green
• D) White

Polarization of light is defined as:

• A) The process of light passing through a polar bear.
• B) The process of light aligning with Earth's magnetic field.
• C) The process of light vibrating in a specific direction.
• D) The process of light changing its color.

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.