A. shorter wavelength
B. longer wavelength
C. remains same at all wavelengths
D. wavelength has nothing to do with it
E. none of the above
Correct Answer: shorter wavelength ✔
Last Updated: January 24, 2019
Related MCQs
- The value of Prandtl number for air is about __________?
- Total emissivity of polished silver compared to black body is__________?
- The value of the wavelength for maximum emissive power is given by __________?
- The unit of overall coefficient of heat transfer is__________?
- All radiations in a black body are__________?
- According to Kirchoff’s law, the ratio of emissive power to absorptivity for all bodies is equal to the emissive power of a __________?
- Joule sec is the unit of__________?
- The concept of overall coefficient of heat transfer is used in case of heat transfer by__________?
- In counter flow heat exchangers__________?
- Fourier’s law of heat conduction is valid for__________?
- LMTD in case of counter flow heat exchanger as compared-to parallel flow heat exchanger is __________?
- According of Kirchhoff’s law__________?
- A steam pipe is to be insulated by two insulating materials put over each other . For best results__________?
- In heat exchangers, degree of approach is defined as the difference between temperatures of__________?
- A non-dimensional number generally associated with natural convection heat transfer is__________?
- Emissivity of a white polished body in comparison to a black body is__________?
- Two balls of same material and finish have their diameters in the ratio of 2 : 1 and both are heated to same temperature and allowed to cool by radiation. Rate of cooling by big ball as compared to smaller one will be in the ratio of__________?
- Heat conducted througfi unit area and unit thick face per unit time when temperature difference between opposite faces is unity,is called__________?
- A grey body is one whose absorptivity__________?
- The rate of energy emission from unit surface area through unit solid angle, along a normal to the surface, is known as __________?
- In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by__________?
- Unit of thermal diffusivity is__________?
- Film coefficient is defined as Inside diameter of tube__________?
- Thermal conductivity of wood depends on__________?
- Thermal diffusivity is __________?
- Moisture would find its way into insulation by vapour pressure unless it is prevented by __________ ?
- Heat transfer by radiation mainly depends upon__________?
- Which of the following has maximum value of thermal conductivity__________?
- The amount of heat flow through a body by conduction is__________?
- Heat flows from one body to other when they have__________?
- Which of the following has least value of conductivity__________?
- Thermal conductivity of glass-wool varies from sample to sample because of variation in __________ ?
- According to Prevost theory of heat exchange __________?
- Thermal diffusivity of a substance is __________?
- The ratio of heat flow Q1/Q2 from two walls of same thickness having their thermal conductivities as ATj – 2K2 will be __________?
- Heat is transferred by all three modes of transfer, viz, conduction, convection and radiation in __________?
- Thermal conductivity of a material may be defined as the__________?
- Which of the following is expected to have highest thermal conductivity__________?
- In heat transfer, conductance equals conductivity (kcal/hr/sqm/°C/cm) divided by __________?
- The time constant of a thermocouple is__________?
- Thermal conductivity of water at 20°C is of the order of__________?
- Total heat is the heat required to__________?
- Thermal conductivity of air with rise in temperature__________?
- Thermal conductivity of air at room temperature in kcal/m hr °C is of the order of__________?
- Cork is a good insulator because it has__________?
- Metals are good conductors of heat because__________?
- Temperature of steam at around 540°C can be measured by __________?
- Thermal conductivity of water in general with rise in temperature __________?
- Which of the following is a case of steady state heat transfer __________?
- Which of the following is the case of heat transfer by radiation __________?
- Heat flowing from one side to other depends directly on __________?