Related Questions

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
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
Maximum amount of thermal radiation is emitted at all wavelengths at any specified temperature by a/an __________ body.
A Grey
B Black
C Opaque
D White
The radiation emitted by a black body is known as
A Black radiation
B Full radiation
C Total radiation
D All of these
The absorptivity of a grey body at a given temperature __________ with increasing wavelength of radiation.
A Increases
B Decreases
C Remains constant
D May increase or decrease ; depends on the material
Heat transfer by radiation from a hot body will be most rapid, if its surface is __________ because of its higher emissivity.
A White & rough
B Black & rough
C White & polished
D Black & polished
The change in length due to a tensile or compressive force acting on a body is given by (where P = Tensile or compressive force acting on the body, $$l$$ = Original length of the body, A = Cross-sectional area of the body and E = Young's modulus for the material of the body)
A $$\frac{{{\text{P}}l{\text{A}}}}{{\text{E}}}$$
B $$\frac{{{\text{P}}l}}{{{\text{AE}}}}$$
C $$\frac{{\text{E}}}{{{\text{P}}l{\text{A}}}}$$
D $$\frac{{{\text{AE}}}}{{{\text{P}}l}}$$
Radiation energy is emitted by all the substances, which are above
A 0°K
B 0°C
C 100°C
D Room temperature
একটি ধাতুর ওপর সবুজ আলো আপতিত হলে ফটোইলেক্ট্রন নির্গত হয়। নিচের কোন বর্ণের আলো আপতিত হলে ঐ তল থেকে অবশ্যই ফটোইলেক্ট্রন নির্গত হবে? (A metal surface emits photoelectrons when illuminated by green light. Illumination with which of the following colour of light will definitely cause photoelectrons to be emitted from the surface?)
A লাল (Red)
B হলুদ (Yellow)
C নীল (Blue)
D কমলা (Orange)
The portion of incident radiation (energy) without heating that surface reflected back from a surface of a body is called:
A Streto
B Ironodo
C Albedo
D Thermedo

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