2018 JAMB PHYSICS PAST QUESTIONS AND ANSWERS

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

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

Positive charge means deficit of electrons, negative charge means excess of electrons, and current is the flow of electrons. All statements are correct.

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

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

Calculate using the formula for series and parallel resistances. The resultant resistance is 8Ω.

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

Cathode rays are streams of electrons. They are negatively charged particles.

Different colours travel at different speeds in glass, causing dispersion and separation into the spectrum.

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

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

Heat capacity refers to the amount of heat required to raise the temperature of a substance by 1K.

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

Shadows and eclipses occur due to the rectilinear propagation of light, where light travels in straight lines.

Ohm’s Law applies to metallic conductors where current is proportional to voltage at constant temperature.

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

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

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

Pressure in chamber G is 760 – 100 = 660 mmHg.

Accumulators (lead-acid batteries) have the lowest internal resistance among the listed options.

Pitch is determined by the frequency of the sound wave; increasing the frequency increases pitch.

Fission reactions lead to chain reactions as neutrons released cause further fission events.

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

Using conservation of momentum and calculating KE, the final kinetic energy is 50 J.

In resonance, the inductor and capacitor voltages cancel each other out. Thus, the capacitor voltage is 40 V.

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

Resonance occurs when the natural frequencies match. R and T resonate with P.

Newton’s law of cooling states the rate of heat loss is proportional to the temperature difference.

By induction, the sphere acquires a negative charge.

Earthing prevents electric shock by maintaining appliances at earth potential.

Evaporation occurs when molecules at the surface of a liquid gain enough energy to transition to the gas phase.

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

The spacing and intermolecular forces in solids, liquids, and gases determine their unique characteristics.

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

Quality (timbre) distinguishes instruments playing the same note due to differences in overtones and waveforms.

South poles induce opposite polarity at T and V, resulting in north and south poles respectively.

Parallel connections ensure devices receive the same voltage and allow independent operation.

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

Using mechanical advantage and efficiency relationships, the effort required is 100 N.

Using capacitance in series and parallel formulas, the effective capacitance is calculated as 1 μF.