2018 JAMB PHYSICS PAST QUESTIONS AND ANSWERS

$$\text{Using the Pythagorean theorem and trigonometric ratios, displacement is calculated as } \sqrt{2} \, \text{km in direction N45°E.}$$

$$\text{Using conservation of mass, new volume is calculated as } 400 \times \frac{0.9}{0.6} = 600 \text{ cm}^3.$$

$$\text{Positive charge means deficit of electrons, negative charge means excess of electrons, and current is the flow of electrons. All statements are correct.}$$

$$\text{Natural radioactivity involves the emission of } \alpha\text{-particles, } \beta\text{-rays, and } \gamma\text{-rays.}$$

$$\text{Images in a plane mirror are virtual, erect, laterally inverted, and of the same size and distance as the object. They are not magnified.}$$

$$\text{Calculate using the formula for series and parallel resistances. The resultant resistance is 8} \Omega.$$

$$\text{Steam engines convert heat to kinetic energy, which is then converted to electricity and eventually to heat and light in a lamp.}$$

$$\text{Cathode rays are streams of electrons. They are negatively charged particles.}$$

$$\text{Different colours travel at different speeds in glass, causing dispersion and separation into the spectrum.}$$

$$\text{Using the efficiency formula, } W = \frac{120}{0.4} = 48 \text{ N.}$$

$$\text{The equation represents a nuclear fission reaction in which a heavy nucleus splits into smaller nuclei, releasing energy and neutrons.}$$

$$\text{Heat capacity refers to the amount of heat required to raise the temperature of a substance by 1K.}$$

$$\text{Using } m = ZIt, I = \frac{m}{Zt} = \frac{36}{0.0012 \times 300} = 100 \, A.$$

$$\text{Shadows and eclipses occur due to the rectilinear propagation of light, where light travels in straight lines.}$$

$$\text{Ohm’s Law applies to metallic conductors where current is proportional to voltage at constant temperature.}$$

$$\text{All three statements are correct: isotopes have identical protons and electrons but different neutrons, affecting physical properties.}$$

$$\text{From the setup, the static friction coefficient depends on the mass ratio: } \mu = \frac{m_2}{m_1}. $$

$$\text{A mirage is explained by all three phenomena due to refraction and total internal reflection in hot air layers.}$$

$$\text{Pressure in chamber G is } 760 – 100 = 660 \text{ mmHg.}$$

$$\text{Accumulators (lead-acid batteries) have the lowest internal resistance among the listed options.}$$

$$\text{Pitch is determined by the frequency of the sound wave; increasing the frequency increases pitch.}$$

$$\text{Fission reactions lead to chain reactions as neutrons released cause further fission events.}$$

$$\text{Volume expansion is } \Delta V = \beta V_0 \Delta T, \text{ where } \beta = 3 \times \alpha. \text{ Calculating gives } 15.09 \text{ cm}^3.$$

$$\text{Using conservation of momentum and calculating } KE, \text{ the final kinetic energy is } 50 \text{ J.}$$

$$\text{In resonance, the inductor and capacitor voltages cancel each other out. Thus, the capacitor voltage is } 40 \text{ V.}$$

$$\text{Using the formula } (\frac{1}{2})^n = \frac{1}{64}, n = 6. \text{ Half-life = } \frac{120}{6} = 20 \text{ years.}$$

$$\text{Resonance occurs when the natural frequencies match. R and T resonate with P.}$$

$$\text{Newton’s law of cooling states the rate of heat loss is proportional to the temperature difference.}$$

$$\text{By induction, the sphere acquires a negative charge.}$$

$$\text{Earthing prevents electric shock by maintaining appliances at earth potential.}$$

$$\text{Evaporation occurs when molecules at the surface of a liquid gain enough energy to transition to the gas phase.}$$

$$\text{The diagram showing two layers of n-type material with a p-type layer in between represents an n-p-n transistor.}$$

$$\text{The spacing and intermolecular forces in solids, liquids, and gases determine their unique characteristics.}$$

$$\text{Convex mirrors produce erect, virtual, and diminished images, making them ideal for a wider field of view in driving.}$$

$$\text{Quality (timbre) distinguishes instruments playing the same note due to differences in overtones and waveforms.}$$

$$\text{South poles induce opposite polarity at T and V, resulting in north and south poles respectively.}$$

$$\text{Parallel connections ensure devices receive the same voltage and allow independent operation.}$$

$$\text{Angular velocity } \omega = \frac{v}{r}, \text{ where } v = 1 \text{ m/s and } r = 0.5 \text{ m. Calculating gives } \omega = 2 \text{ rad/s.}$$

$$\text{Using mechanical advantage and efficiency relationships, the effort required is } 100 \text{ N.}$$

$$\text{Using capacitance in series and parallel formulas, the effective capacitance is calculated as } 1 \mu F.$$