A ray of light traveling from water (denser) into air (rarer) grazes the interface separating the two media. The angle of incidence in the water is called the: MCQ with Answer and Explanation
A ray of light traveling from water (denser) into air (rarer) grazes the interface separating the two media. The angle of incidence in the water is called the:
A. Angle of refraction
B. Brewster's angle
C. Angle of polarization
D. Critical angle
Answer: Option D
Solution (By JKSSB Mock Tests)
When light travels from an optically denser medium to a rarer medium, it bends away from the normal. As the angle of incidence increases, the angle of refraction also increases. The specific angle of incidence for which the refracted ray grazes the surface (meaning the angle of refraction is exactly 90 degrees) is defined as the critical angle.
Explanation:
Air has mass, gravity pulls it, creating weight. Pressure at any point is weight of air column above per unit area. At sea level ~10⁵ Pa. Decreases with altitude.
Explanation:
Range R = u²sin(2θ)/g = (20)²×sin(60°)/10 = 400×(√3/2)/10 = 20√3 m. Formula applies for level ground projection. Memory tip: sin(2θ) for θ=30° is sin60°=√3/2. Standard projectile calculation frequently appearing in competitive exams with trigonometric values.
Explanation:
The Stefan-Boltzmann law dictates that the total energy radiated per unit surface area of a black body across all wavelengths per unit time (Emissive Power, E) is strictly directly proportional to the fourth power of the black body's thermodynamic (absolute) temperature. E = sigma * T^4, where sigma is the Stefan-Boltzmann constant.
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