Related Questions

In a city 40% of the people have black hair, 25% have black eyes and 10% have both black hair and black eyes. What percentage of the people in the city has neither black hair nor black eyes?
A 35
B 40
C 45
D 50
In a certain city 40% of the people have black hair, 25% have black eyes and 10% have both black hair and black eyes. What percentage of the people in the city have neither black hair nor black eyes?
A 35
B 40
C 45
D 50
Absorptivity and refletivity of a perfect black body are respectively
A 1 and 0
B 0 and 1
C 1 and $$\infty $$
D 0 and 0.5
While the total emissivity of a perfect black body is unity, the same for a real body is
A 0
B 1
C > 1
D Between 0 and 1
A perfect black body is a perfect __________ of radiation.
A Absorber
B Emitter
C Both A & B
D Neither A nor B
What is the absorptivity of a black body?
A 1
B 0
C 0.78
D 0.95
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
The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)
A α.T
B α.$$\frac{1}{{\text{T}}}$$
C α.T4
D Independent of T
A basket contains four balls of four diffirent colors -white red, black and green which will be distributed among for persons Rajib, Litu, Simu, and Rida. Rida must not be given the black one. Simu not be given either the black one or the green one. If the above conditions are fulfilled, Which of the following must be true?
A Simu will be given the red one
B Lity will given the black one
C Rida will be given the green one
D All of these
A box contains 200 marbles, 25% of which are of black colour. Babu took some marbles from the box found that 30% of them are black. Of the remaining marbles, 10% were black marbles. How many marbles did Babu take?
A 120
B 125
C 150
D None of these

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