Bright and dark fringes are seen on a screen when light from a single source reaches two narrow slits a short distance apart. The number of fringes per unit length on the screen can be halved
A.
.B.
.C.
the wavelength is changed to 
.D.
E.
.Answer: D
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In the proton-proton cycle, the helium atom and neutrino have less mass than the original hydrogen. What happens to the "lost" mass?
A) It is recycled back into hydrogen. B) It is ejected into space. C) It is converted to energy. D) It is transformed into electrons. E) Conservation of mass dictates no mass can be lost.
In addition to nitrogen, the other main components of Titan's atmosphere are
A) ammonia and water vapor B) hydrogen and helium C) oxygen and carbon dioxide D) hydrocarbons like methane and ethane
The electron spin quantum number can take on what values?
What will be an ideal response?
A long, heated, cylindrical steel rod is removed from a heat treatment furnace and has to be cooled to complete the process. If the surface temperature of the rod is at 150°C and the cooling fluid temperature is maintained at 25°C, what is the minimum diameter of the rod to produce turbulent natural convection heat transfer if it is held in a horizontal position in (a) air and (b) water? Also, determine the initial heat transfer rate by natural convection from a 10-cm diameter rod in each of the two fluids.
GIVEN
• Long heated cylindrical steel rod, cooled by natural convection.
• Surface temperature of rod (Ts=1500C
• Fluid temperature (T?) = 250C
FIND
(a) Minimum diameter of rod to produce turbulent natural convection in (i) Air (ii) water
(b) Initial heat transfer rate by natural convection from 10 cm diameter rod in each fluids.
ASSUMPTIONS
• Radiation is negligible
SKETCH
PROPERTIES AND CONSTANTS
for dry air at the mean temperature of 87.5°C
Thermal expansion coefficient (?) = 0.00277 1/K
Thermal conductivity (k) = 0.0298 W/(m K)
Kinematic viscosity (?) = 22.55 × 10–6 m2/s
Prandtl number (Pr) = 0.71
for water at the mean temperature of 87.5°C
Thermal expansion coefficient (?) = 0.000678 1/K
Thermal conductivity (k) = 0.6765 W/(m K)
Kinematic viscosity (?) = 0.33 × 10–6 m2/s
Prandtl number (Pr) = 67.8