Physics 2019 Jamb Examination

Maintaining the specific gravity of the electrolyte (sulphuric acid) is crucial for the health of a lead-acid battery. It should typically be around 1.25 for a fully charged battery. Option A is dangerous (only distilled water should be added to top up), Option B is a fire hazard due to hydrogen gas emission, and Option D causes short-circuiting.

Relative Humidity (R.H.) is the ratio of the mass of water vapour present to the mass required for saturation at the same temperature, expressed as a percentage:\[ \text{R.H.} = \frac{\text{Actual mass}}{\text{Saturated mass}} \times 100 \]\[ \text{R.H.} = \frac{0.05}{0.15} \times 100 = \frac{1}{3} \times 100 = 33.33\% \]

Angular dispersion is the difference in the angles of deviation for two different colors (usually red and violet). Since the deviation produced by a prism depends on the angle of incidence and the refractive index (which varies for different wavelengths), the dispersion is affected by both.

Statements I, II, and III are fundamental properties of mechanical waves. Statement IV is only true for electromagnetic waves; mechanical waves (like sound or water waves) *do* require a medium. Since the question asks generally about waves, and IV is not universally applicable, D is the best choice.

1. Volume \( V = 0.1 \times 0.05 \times 0.02 = 0.0001 \; \text{m}^3 \).
2. Mass \( m = \text{Density} \times V = 100 \times 0.0001 = 0.01 \; \text{kg} \).
3. Weight (Force) \( F = mg = 0.01 \times 10 = 0.1 \; \text{N} \).
4. Area (max pressure is on smallest side, but typically assumed to be resting on largest face unless specified). Area \( A = 0.1 \times 0.05 = 0.005 \; \text{m}^2 \).
5. Pressure \( P = \frac{F}{A} = \frac{0.1}{0.005} = 20 \; \text{N/m}^2 \).

In a simple pendulum, potential energy is maximum at the extreme positions (highest points) and minimum at the equilibrium (lowest) position. Conversely, kinetic energy is maximum at the lowest point (mean position) because that is where the bob travels fastest. In the standard labeling for this diagram, the mean position is usually the center point.

For equilibrium, two conditions must be met: the resultant force must be zero and the resultant moment must be zero. Options A, B, and D are correct descriptions of these conditions. Option C is 'not correct' because while forces don't *have* to be equal, the statement itself is not a condition for equilibrium; it's a general observation.

According to the Law of Conservation of Mechanical Energy, in the absence of air resistance, the total mechanical energy (Sum of P.E. and K.E.) remains constant throughout the fall. As the body falls, P.E. decreases while K.E. increases, but their sum is invariant.

Conduction relies on molecular collisions and free electrons. In solids, particles are closely packed, allowing for efficient energy transfer. In liquids and especially gases, particles are farther apart, making conduction much less efficient. Heat transfer in fluids is primarily achieved through convection.

Pressure in a liquid (hydrostatic pressure) is given by: \[ P = h \rho g \] Given: \( h = 1 \, \text{km} = 1000 \, \text{m} \) \( \rho = 950 \, \text{kg/m}^3 \) \( g = 10 \, \text{m/s}^2 \) \[ P = 1000 \times 950 \times 10 = 9,500,000 \, \text{N/m}^2 = 9.5 \times 10^6 \, \text{N/m}^2 \]