JAMB Physics 2023
Questions & Answers

A student might incorrectly select options A, C, or D by misinterpreting how pressure, volume, and temperature interact. Option B is correct because the universal gas constant (R) and number of moles (n) relate pressure (P), volume (V), and temperature (T) via PV = nRT, which relies on ideal conditions and the absence of intermolecular forces. Common mistake: Confusing the direct and inverse relationships among the variables in the ideal gas equation.

A student might mistakenly choose options A, C, or D by overlooking the dominant astronomical influence on ocean levels. Option B is correct because the Moon exerts a gravitational force on the oceans that generates high and low tides, and while the Sun also contributes, the Moon's closer proximity makes its gravitational effect dominant. Common mistake: Assuming solar radiation or Earth's rotation is the primary tidal driver instead of lunar gravity.

A student might mistakenly select options A, C, or D by assuming certain variables can be known simultaneously or without limits. Option B is correct because Heisenberg's uncertainty principle sets a fundamental limit where simultaneous precision of position and momentum is restricted, mathematically expressed as Δx·Δp ≥ ħ/2 with ħ as the reduced Planck's constant. Common mistake: Believing that advanced measurement tools can bypass fundamental limits on position and momentum precision.

A student might mistakenly choose options A, C, or D by performing incorrect arithmetic operations during the calculation. Option B is correct because kinetic energy is determined using KE = (1/2)mv^2, substituting the mass of 2 kg and velocity of 4 ms^-1 to yield (1/2) * 2 * 16, resulting in 16 J. Common mistake: Forgetting to square the velocity value in the kinetic energy formula.

A student might mistakenly select options A, B, or D by misunderstanding the direction or permanence of charge flow in an isolated setup. Option C is correct because the law of conservation of charge dictates that the total electric charge in a closed system remains constant, meaning charge cannot be created or destroyed, only transferred between objects. Common mistake: Thinking that charges can be spontaneously created or destroyed within an isolated boundary.

A student might mistakenly choose options A, B, or D by confusing electrical generation with voltage transformation, storage, or motor operation. Option C is correct because a generator transforms mechanical energy into electrical energy using electromagnetic induction. Common mistake: Confusing electrical generators with electric motors, which perform the reverse conversion.

A student might mistakenly select options A, C, or D by assuming internal energy is fixed or depends entirely on a single factor. Option B is correct because the first law of thermodynamics states that the change in internal energy (ΔU) is calculated as heat added (Q) minus work done by the system (W), expressed as ΔU = Q - W to reflect energy conservation. Common mistake: Forgetting to subtract the work done by the system when calculating internal energy changes.

A student might mistakenly choose options A, C, or D by executing improper division when relating wave properties. Option B is correct because wavelength is derived using λ = v / f, dividing the velocity of 20 ms^-1 by the frequency of 40 Hz to yield 0.50 m. Common mistake: Multiplying speed and frequency instead of dividing speed by frequency to find wavelength.

A student might mistakenly select options A, C, or D by assuming a rotating system's momentum always shifts over time or drops to zero. Option B is correct because the law of conservation of angular momentum states that angular momentum remains constant if no external torque acts on the system, which can be observed when spinning objects like figure skaters pull in their arms. Common mistake: Forgetting that external torque is required to alter a system's total angular momentum.

A student might mistakenly choose options A, C, or D by picking diverging or non-magnifying optical components. Option B is correct because a magnifying glass employs a convex lens to converge light and produce a magnified virtual image whenever the object is placed inside the focal length. Common mistake: Confusing the converging properties of convex lenses with the diverging nature of concave lenses.

A student might mistakenly select options A, C, or D by ignoring how relative motion impacts the passage of time. Option B is correct because Einstein's theory of relativity dictates that time dilation causes time to pass slower for a moving observer relative to a stationary observer, which becomes significant at relativistic speeds. Common mistake: Assuming time passes at a universal, identical rate regardless of relative motion.

A student might mistakenly choose options B, C, or D by miscalculating total resistance or incorrectly applying Ohm's law. Option A is correct because the total resistance R is the sum of the two 5 Ω resistors in series (5 + 5 = 10 Ω), and the total current I equals voltage divided by resistance (10 V / 10 Ω = 1 A) according to Ohm's law. Common mistake: Failing to sum series resistors correctly before calculating the current.

A student might mistakenly select options A, C, or D by assuming mass and energy are strictly separated or conserved independently. Option B is correct because Einstein's mass-energy equivalence formula (E = mc^2) establishes that mass and energy can be converted into one another, with total mass-energy being conserved in events like nuclear reactions. Common mistake: Treating mass and energy as entirely distinct entities without recognizing their equivalence.

A student might mistakenly choose options A, B, or D by assuming convex lenses only create virtual views, diverge rays, or are thinner at the center. Option C is correct because a convex lens can form real images when an object sits outside the focal point, or virtual images when inside the focal point, while also converging light and being thicker at the center. Common mistake: Believing convex lenses are incapable of forming real images.

A student might mistakenly select options A, C, or D by assuming momentum is lost or gained during impacts without accounting for external influences. Option B is correct because the law of conservation of linear momentum states that the total momentum before a collision equals the total momentum after as long as no external forces, such as friction, act on the objects. Common mistake: Overlooking the requirement that no external forces must be present for total momentum to remain constant.

A student might mistakenly choose options A, C, or D by misapplying kinematic formulas for vertical motion. Option B is correct because final velocity v is zero at maximum height, allowing us to use v^2 = u^2 - 2gh to find 0 = 10^2 - 2 * 10 * h, which simplifies to 100 = 20h and yields h = 5.0 m. Common mistake: Incorrectly substituting values into the kinematic equation for vertical projectile motion.

A student might mistakenly select options A, C, or D by confusing how identical and opposite electric charges interact. Option B is correct because Coulomb's law dictates that like charges repel and unlike charges attract, with the force being proportional to the product of the charges and inversely proportional to the square of the distance between them. Common mistake: Mixing up the attraction and repulsion rules for like versus unlike charges.

A student might mistakenly choose options A, C, or D by assuming a dielectric has no effect or reduces capacitance. Option B is correct because inserting a dielectric material increases capacitance by lowering the electric field between the plates, which permits greater charge storage. Common mistake: Believing that inserting a dielectric decreases the overall capacitance of the device.

A student might mistakenly select options A, C, or D by assuming radioactive decay rates stay fixed over time or rise with temperature. Option B is correct because the law of radioactive decay states that the rate of decay is proportional to the number of undecayed nuclei, resulting in exponential decay represented by dN/dt = -λN, where λ is the decay constant. Common mistake: Assuming the rate of radioactive decay remains constant rather than decreasing as undecayed nuclei are depleted.

A student might mistakenly choose options B, C, or D by calculating the wrong number of half-life intervals. Option A is correct because 6 hours equals 3 half-lives when divided by a 2-hour half-life, meaning the initial activity of 800 counts per minute halves successively to 400, then 200, and finally 100 counts per minute. Common mistake: Multiplying instead of dividing the total time by the half-life duration.