Related Questions

Absorptivity of a perfect black body is unity. Which of the following has maximum absorptivity?
A Aluminium foil
B Refractory bricks
C Iron plate
D Coke breeze
A grey body is one whose absorptivity
A Varies with temperature
B Varies with wavelength of the incident ray
C Is equal to its emissivity
D Does not vary with temperature and. wavelength of the incident ray
Absorptivity of a grey body varies with the
A Wavelength of the incident ray
B Temperature
C Both A & B
D Neither A nor B
Addition of small amount of __________ to grey cast iron is done to produce nodular grey cast iron.
A Manganese
B Phosphorous
C Magnesium
D Chromium
In thermal radiation for a black body (where, ε is emissivity and α is absorptivity)
A α = 1; ε ≠ 1
B α ≠ 1, ε = 1
C α ≠ 1, ε ≠ 1
D α = 1; ε = 1
A 'body' which allows the short wavelength incoming solar radiation to enter in, but does not allow long wave length outgoing infra red radiation to escape out is called the
A Global warming
B Green house
C Atmospheric effect
D Ionosphere
There are five persons sitting on a bench. Blue eyed lady sitting in the middle is my mother. At the extreme left, the man with grey hair is my maternal uncle. Lady sitting at the extreme right is having a pimple on her nose and is the wife of person who is sitting between blue eyed lady and grey haired man and has a pointed nose. A lady having marks on her face is the younger sister of the blue eyed lady and sitting on the remaining fifth place. The person having a pointed nose is the son of the blue eyed lady. What is the lady having marks on her face to the man sitting at extreme left ?
A Wife
B Maternal Aunt
C Sister
D Sister-in-law
একটি ধাতব তলে λ তরঙ্গদৈর্ঘ্যের একবর্ণী আলোকরশ্মি আপতিত হলে ফটো-ইলেক্ট্রন নির্গত হয় এবং এক্ষেত্রে বিভবের মান 3Vo একই তলে যখন 2λতরঙ্গদৈর্ঘ্যের একবর্ণী আলো আপতিত হয়, তখন নিবৃত্তি বিভবের মান Vol ফটো-ইলেক্ট্রন নির্গত হওয়ার জন্য ঐ তলটির সূচন তরঙ্গদৈর্ঘ্যের মান নির্ণয় কর।(A monochromatic light of wavelength λ is incident on a metallic surface then ejects photo-electron and the value of stopping potential is 3Vo. When the same surface is illuminated by a light of wavelength 2λ., the stopping potential becomes Vo. Calculate the threshold wavelength for this surface to eject photo electrons.)
A 6λ
B 8λ
C 4λ3
D λ
E 4λ
The ratio of total radiating power to the absorptivity of the body depends upon the __________ as per Kirchoffs law.
A Wavelength of radiation
B Nature of the body
C Temperature of the body
D None of these
Wavelength of radiation emitted by a body depends on the __________ of its surface.
A Temperature
B Area
C Nature
D All of the above

Next steps