A certain metallic surface is illuminated with
monochromatic light of wavelength, l. The stopping
potential for photo-electric current for this light is
3V₀. if the same surface is illuminated with light of
wavelength 2λ, the stopping potential is V0. The
threshold wavelength for this surface for photoelectric
effect is :-

A Carnot engine, having an efficiency of n = 1/10 as
heat engine, is used as a refrigerator. If the work
done on the system is 10 J, the amount of energy
absorbed from the reservoir at lower temperature is 

Which logic gate is represented by the following
combination of logic gates ?

The refracting angle of a prism is A, and refractive
index of the material of the prism is cot(A/2). The
angle of minimum deviation is :-

The fundamental frequency of a closed organ pipe
of length 20 cm is equal to the second overtone of
an organ pipe open at both the ends. The length
of organ pipe open at both the ends is :-

A parallel plate air capacitor of capacitance C is
connected to a cell of emf V and then disconnected
from it. A dielectric slab of dielectric constant K,
which can just fill the air gap of the capacitor, is now
inserted in it. Which of the following is incorrect