WAEC Physics 2025
Questions & Answers

One might mistakenly select an eclipse or shadow, which involve light blocking rather than color separation. When white light passes through a medium, different wavelengths refract at varying angles, splitting the beam into its component colors to create a natural phenomenon like a rainbow. Common mistake: Confusing light obstruction phenomena with the spectral separation caused by refraction.

Darker shades like black or red might be chosen under the false assumption of blocking light entirely, but they absorb thermal energy rapidly. A white garment reflects the vast majority of incoming solar radiation, helping the wearer stay much cooler under intense midday heat. Common mistake: Choosing dark colors under the misconception that they block sunlight better.

A student might pick a virtual or diminished image configuration by confusing lens types or object placements. Positioning an item between the focal point and twice the focal length of a converging lens yields a real, inverted, and magnified image located beyond twice the focal length. Common mistake: Forgetting the image characteristics produced when an object lies within the 2F and F region of a converging lens.

Terms like Lorentz ratio or charge ratio are tempting distractors for those guessing based on naming conventions. When electric and magnetic forces counteract each other on a moving charge, taking the ratio of electric field intensity to magnetic flux density yields the specific particle speed isolated by a velocity selector. Common mistake: Guessing complex-sounding ratios instead of identifying the specific mechanical device function represented by the E/B field ratio.

A reader might confuse pitch with loudness or assume different instruments sharing a frequency have identical qualities. Since sound wave amplitude dictates loudness, the larger amplitude of 1.5cm makes note M louder than note K, while their matching frequency guarantees an identical pitch. Common mistake: Confusing frequency (pitch) with amplitude (loudness).

A test-taker might miscalculate the period or misapply the pendulum formula constants. Finding the period T as sixty seconds divided by twenty oscillations gives three seconds, which can then be inserted into the formula g = 4π²L/T² using length 0.8m and π = 3.14 to arrive at approximately 3.0 ms⁻². Common mistake: Forgetting to square the period term in the denominator when calculating gravitational acceleration.

A student might simply average the temperatures without considering mass symmetry or make arithmetic errors in heat transfer equations. Given equal masses of the identical liquid, the conservation of thermal energy dictates that the heat lost by the warmer liquid equals the heat gained by the cooler one, resulting in a direct midpoint temperature of 41°C. Common mistake: Failing to recognize that equal masses of the same substance result in an arithmetic mean for the final equilibrium temperature.

One might guess the first law, which deals with conservation of energy, rather than the foundational rule of thermal measurement. The principle establishing that thermal equilibrium acts transitively across separate bodies interacting with a third reference body is formally designated as the zeroth law of thermodynamics. Common mistake: Confusing the transitiveness of thermal equilibrium with the energy conservation principles of the first law.

Students might mistakenly choose Ampere because current is a prominent variable in electrical formulas, but Ampere measures electric current rather than the total quantity of charge itself. To determine the correct designation, one must look at the fundamental definition where the coulomb (C) represents the total electric charge transported by a current of 1 ampere flowing continuously in 1 second. Common mistake: confusing the unit of electric current with the unit of electric charge.

A student might be tempted to pick 50J by incorrectly halving one of the intermediate steps or misapplying the time factor. To solve this properly, first find the final velocity after falling from rest for 2 seconds by multiplying acceleration due to gravity by time, yielding v = gt = 10 * 2 = 20 ms⁻¹. Next, apply this velocity into the kinetic energy equation, giving KE = (1/2)mv² = 0.5 * 5 * 400 = 100 J. Common mistake: failing to square the velocity term during the kinetic energy calculation.

One might incorrectly select 3.0 × 10⁸ms⁻¹ by confusing the speed of light in medium A or the vacuum with the final answer for medium B. To solve this correctly, first calculate the speed of light in a vacuum by multiplying the refractive index of medium A by its given speed, which gives c = n_A * v_A = 1.5 * 2.0e8 = 3.0e8 ms⁻¹. Afterwards, determine the speed of light in medium B by dividing this vacuum speed by medium B's refractive index, resulting in v_B = c / n_B = 3.0e8 / 1.2 = 2.5e8 ms⁻¹. Common mistake: dividing instead of multiplying when finding the speed in a vacuum from a given medium.

A student might select 60,000s by multiplying the wavelength and speed values instead of dividing them. To arrive at the correct period, one must use the relationship where period is derived by dividing the wavelength by the speed of the wave, yielding T = λ / v = 600 / 360 ≈ 1.667 s. Common mistake: multiplying speed and wavelength instead of dividing wavelength by speed.

A student might mistakenly select Wheelbarrow because it is a common everyday lever example, but a wheelbarrow is a class 2 lever where the load sits between the fulcrum and the effort. Sugar tongs are identified as the correct answer because they operate as a class 3 lever arrangement where the effort is applied between the fulcrum and the load. Common mistake: confusing class 2 levers (load in the middle) with class 3 levers (effort in the middle).

A student might mistakenly pick 10W by multiplying current and resistance directly without squaring the current first. The correct power dissipated is found by squaring the current and multiplying it by the resistance value, yielding P = I²R = 2² * 5 = 20 W. Common mistake: forgetting to square the current value when using the I²R formula.

One might choose 10V by simply copying the resistance value given in the problem statement without performing any multiplication. The potential difference is correctly calculated by multiplying the current by the resistance, yielding V = IR = 0.5 * 10 = 5 V. Common mistake: treating the resistance value as the final voltage without multiplying by the current.

A student might mistakenly pick option A or D by either including electrons inside the nucleus or missing the fact that atomic decay stems from nuclear instability. The correct attributes are that the atomic nucleus is centrally located (I), carries a positive charge due to the presence of protons (III), and undergoes radioactive decay when internal instability arises (IV); however, statement II is false because the nucleus contains nucleons—protons and neutrons—rather than electrons. Common mistake: assuming electrons reside inside the nucleus alongside protons and neutrons.

A student might mistakenly select 2.5 days by dividing the final mass by the total days or miscalculating the number of division steps. To find the half-life, first track the decay stages from 16g down to 1g, which requires 4 half-lives as the mass halves sequentially through 16→8→4→2→1. Since this entire reduction process takes a total of 40 days, dividing the total duration by the number of half-lives gives 40 / 4 = 10.0 days. Common mistake: miscounting the number of half-life steps between the initial and final mass values.

A student might choose options A or B, thinking that acoustic treatment is meant to amplify or make sound louder in a venue. Perforated pads are actually installed to absorb sound waves, which successfully diminishes echoes and minimizes the effect of reverberation of sound waves to ensure acoustic clarity. Common mistake: confusing sound absorption treatments with sound amplification systems.

One might mistakenly select 41.7N by calculating only the centripetal force component or forgetting to add the weight of the bucket. At the lowest position of the vertical swing, the tension must counteract gravity while also providing the necessary centripetal force, meaning T - mg = mv²/r. Rearranging and solving gives T = mg + mv²/r = (10 * 10) + (10 * 25 / 1.2) = 100 + 208.3 ≈ 308.3 N. Common mistake: omitting the weight of the object (mg) when calculating tension at the lowest point of a vertical circle.

A student might mistakenly select Myopia because it is a very common vision condition, but myopia involves a near point closer than normal rather than one pushed out to 30cm. The correct defect is hypermetropia, where farsightedness causes the near point to be located farther than the normal 25cm distance. Common mistake: confusing myopia (nearsightedness) with hypermetropia (farsightedness).