1. Experimental investigations show that the intensity of solar radiation is maximum for a wavelength 480 nm in the visible region. Estimate the surface temperature of sun. Given Wein’s constant b = 2.88 × 10–3 mK.
(A) 4000 K (B) 6000 K (C) 8000 K (D) 106 K
2. The temperature of an ideal gas is increased from 120 K to 480 K. If at 120 K, the root mean square speed of gas molecules is v, then at 480 K it will be
(A) 4v (B) 2v (C) 2v (D) 4v
3. Two mirrors at an angle θº produce 5 images of a point. The number of images produced when θ is decreased to θº – 30º is
(A) 9 (B) 10 (C) 11 (D) 12
4. The radius of the light circle observed by a fish at a depth of 12 meter is (refractive index of water = 4/3)