Govt. Exams
Entrance Exams
The Second Law of Thermodynamics states that for an isolated system, entropy always increases or remains constant, never decreases. This defines the direction of spontaneous processes and the arrow of time.
The lens formula relates object distance, image distance, and focal length for any lens system.
We are given the focal length (f) = 15 cm and image distance (v) = 30 cm. We need to find the object distance (u) using the lens formula.
The lens formula relates these three quantities. Rearranging to solve for object distance:
In the standard sign convention for lenses, the object distance is measured from the lens. Since the object is placed on the side from which light enters (a real object), it is taken as negative.
The object distance is -30 cm (Option D).
Linear expansion: ΔL = α × L₀ × ΔT = 1.2 × 10⁻⁵ × 1 × 100 = 1.2 × 10⁻³ m = 1.2 mm.
Work done against constant pressure: W = -PΔV. Given W = -500 J and P = 2 atm = 2 × 101325 Pa. ΔV = -W/P = 500/(2 × 101325) ≈ 2.47 × 10⁻³ m³ = 2.47 L.
De Broglie proposed that all matter exhibits wave-particle duality. Both light (photons) and electrons show properties of both waves and particles, confirmed by experiments like double-slit interference and photoelectric effect.
Ferromagnetism is the property of materials like iron, cobalt, and nickel to retain permanent magnetic properties due to aligned electron spins.
For parallel connection: 1/R = 1/6 + 1/3 + 1/2 = 1/6 + 2/6 + 3/6 = 6/6 = 1. Therefore R = 1Ω.
Work by gravity W = -mgh (negative because displacement is opposite to force direction). W = -5 × 10 × 10 = -500 J.
Insulin, produced by the pancreas, lowers blood glucose by facilitating glucose uptake into cells. Glucagon raises blood glucose levels.
Elastic potential energy U = ½kx². U = ½ × 100 × (0.2)² = 50 × 0.04 = 2 J.
