KVPY (Kishore Vaigyanik Protsahan Yojana) Stream SBSX (Class 12 & 1st Year B.Sc.) Physics: Questions 219  222 of 268
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Question number: 219
» Thermodynamics » Concept of Temperature
Question
A solid copper sphere cools at the rate of 3.2^{0} C per minute, when its temperature is 177^{0} C. Find the rate at which another solid copper sphere of twice the radius lose its temperature at 377^{0} C, if in both the cases, the room temperature is maintained at 27^{0} C.
Choices
Choice (4)  Response  

a. 


b.  7.290C min1 

c. 


d. 


Question number: 220
» Dual Nature of Matter and Radiation » Photoelectric Effect
Question
If the wavelength of photon emitted due to transition of electron from third orbit to first orbit in a hydrogen atom is λ, then the wavelength of photon emitted due to transition of electron from fourth orbit to second orbit will be –
Choices
Choice (4)  Response  

a. 


b. 


c. 


d. 


Question number: 221
» Gravitation » Gravitational Potential
Question
Two masses m_{1} = 10 kg and m_{2} = 810 kg are held 2 m apart. At a point P on the line joining them is the gravitational field equal to zero. The gravitational potential at that point is –
Choices
Choice (4)  Response  

a. 


b. 


c. 


d. 


Question number: 222
» Atoms and Nuclei » Bohr Model
Appeared in Year: 2015
Question
A donor atom in a semiconductor has a loosely bound electron. The orbit of this electron is considerably affected by the semiconductor material but behaves in many ways like an electron orbiting a hydrogen nucleus. Given that the electron has an effective mass of 0.07m_{e}, (where m_{e} is mass of the electron) and the space in which it moves has a permittivity, then the radius of the electron’s lowermost energy orbit will be close to (The Bohr radius of the hydrogen atom is 0.53 Å)
Choices
Choice (4)  Response  

a.  10 Å 

b.  100 Å 

c.  243 Å 

d.  0.53 Å 
