This JAMB Physics exam paper from 2015 tests fundamental concepts across mechanics, optics, thermodynamics, and modern physics. Students will encounter questions that evaluate core physical principles, including wave motion, electromagnetic induction, radioactivity, and basic electronics. Recurring themes across this year's paper heavily feature calculations involving wave parameters, nuclear processes like fission and fusion, and fundamental electricity principles such as resistance and electrical energy. When working through these questions, make sure to read the step-by-step explanations for every option rather than simply memorizing the final numerical answers, as understanding the underlying formulas is key to success.
Topics in this paper
A piece of rubber 10cm long stretches 6mm when a load of 100N is hung from it. What is the strain?
Students often choose options A, B, or C due to calculation errors or forgetting to convert units properly. Strain is computed by taking the ratio of the extension to the original length. Converting both values into meters gives an extension of 0.006m (from 6mm) and an original length of 0.1m (from 10cm). Dividing 0.006 by 0.1 yields 0.06, which translates in scientific notation to 6.0 x 10⁻². Common mistake: Forgetting to convert millimeters and centimeters into standard SI units before division.
Two resistors of 4Ω and 12Ω are connected in parallel. What is the equivalent resistance?
A learner might mistakenly pick option B by simply adding the resistors together as if they were in series, or choose C or D through arithmetic mistakes. For parallel connections, the equivalent resistance is found using the reciprocal formula: the sum of the inverse of each resistor (1/4 + 1/12). Finding a common denominator results in 3/12 + 1/12, which equals 4/12 or 1/3, meaning the equivalent resistance is 3Ω. Common mistake: Treating parallel resistors like series resistors by adding their resistance values directly.
In an astronomical telescope, the objective lens has a
Options A, C, and D are incorrect because reversing these focal lengths would either fail to gather sufficient light or ruin the magnification needed for distant viewing. An astronomical telescope requires an objective lens with a large focal length to collect abundant light and construct a real image, while its eyepiece needs a short focal length to magnify that image effectively. Common mistake: Confusing the optical roles and focal length requirements of the objective lens versus the eyepiece.
A body of mass 5kg is placed on an inclined plane at 30° to the horizontal. If g = 10ms⁻², the component of the weight parallel to the plane is
One might select options B, C, or D by miscalculating trigonometric functions or using the total weight instead of its vector component. The parallel component of weight down an inclined plane is calculated using the formula mg sin θ. Substituting the given mass (5kg), acceleration due to gravity (10ms⁻²), and the sine of 30° (0.5), we multiply 5 x 10 x 0.5 to arrive at 25N. Common mistake: Multiplying weight by cosine instead of sine for the parallel component.
The speed of light in air is 3.0 x 10⁸ ms⁻¹. The speed in glass having a refractive index of 1.65 is
Options B, C, or D might be chosen if a student multiplies the values instead of dividing, or confuses the formula parameters. The refractive index represents the ratio of the speed of light in air to its speed in a given medium (n = c/v). Rearranging this formula to solve for the speed in glass (v = c/n) requires dividing 3.0 x 10⁸ ms⁻¹ by 1.65, which calculates out to approximately 1.82 x 10⁸ ms⁻¹. Common mistake: Multiplying the speed of light in air by the refractive index instead of dividing.
Longitudinal waves do not exhibit
A student might guess options A, C, or D because all waves undergo reflection, refraction, and diffraction. However, longitudinal waves oscillate parallel to the direction of wave propagation, a particle displacement geometry that inherently prevents them from being polarized, unlike transverse waves. Common mistake: Assuming all wave phenomena apply equally to both transverse and longitudinal wave types.
A device that converts sound energy into electrical energy is
Options A, B, and C are frequently confused because they all deal with audio equipment, but they perform different energy conversions. A microphone utilizes a vibrating diaphragm to transform acoustic sound energy directly into an electrical signal. Common mistake: Confusing input transducers like microphones with output transducers like loudspeakers.
A good calorimeter should be of
Options B, C, or D appear plausible if one misunderstands how thermal energy transfers in laboratory apparatus. A proper calorimeter requires a low specific heat capacity so it absorbs minimal thermal energy itself, alongside low heat conductivity to prevent thermal leakage into the surrounding environment. Common mistake: Believing a calorimeter should absorb heat rather than isolate it.
Which of the following is most strongly deflected by a magnetic field?
One might select options B, C, or D by forgetting particle charges or mass properties. Beta-particles are high-speed electrons possessing a negative charge and very low mass, making them highly susceptible to strong deflection within a magnetic field, whereas alpha particles are heavier and gamma/x-rays are neutral. Common mistake: Confusing the deflection behavior of neutral rays with charged subatomic particles.
If a beaker is filled with water, it is observed that the surface of the water is not horizontal at the glass-water interface. This behavior is due to
Options A, C, and D are fluid properties that affect flow or evaporation, but they do not dictate the boundary shape at a solid-liquid container junction. Surface tension is responsible for forming a distinct meniscus at the glass-water interface due to adhesive forces operating between the water molecules and the glass container. Common mistake: Attributing meniscus formation to general viscosity or fluid friction instead of surface-level molecular forces.
A dynamo primarily converts
A student might select options A, B, or D by mixing up the functions of motors, generators, and other energy transducers. A dynamo operates via electromagnetic induction, rotating a coil to transform mechanical energy directly into electrical energy. Common mistake: Confusing the energy conversion direction of a dynamo with that of an electric motor.
A charged particle is injected into an electric field and follows a curved path. The particle is likely to be
Options A and B are incorrect because uncharged particles do not respond to electric fields, while option D might confuse those who mix up proton and alpha particle mass-to-charge behaviors in simpler contexts. A proton carries a positive electrical charge, causing it to deflect along a curved trajectory when subjected to an electric field's electrostatic forces. Common mistake: Assuming neutral particles like neutrons or gamma rays experience trajectory changes in electric fields.
The frequency of a sound wave is 500Hz and its wavelength is 0.68m. What is the speed of the wave?
Options B, C, or D could arise from arithmetic errors when multiplying wave parameters. Wave speed is determined by the product of frequency and wavelength (v = f x λ). Multiplying 500Hz by 0.68m yields 340ms⁻¹, representing the speed of sound through the medium. Common mistake: Dividing wavelength by frequency instead of multiplying them together.
A calibrated potentiometer is used to measure the e.m.f. of a cell because the
Options A, C, or D highlight general meter traits, but they fail to address the core measurement error caused by current flow. A calibrated potentiometer measures a cell's electromotive force accurately because it balances the circuit without drawing any current from the cell, thus eliminating potential drop across the cell's internal resistance. Common mistake: Overlooking the effect of internal resistance when measuring a cell's true e.m.f.
Which of the following is a vector?
Options A, B, and D are common scalar quantities taught alongside vectors, making them easy distractors if definitions are mixed up. An electric field possesses both a distinct magnitude and a directional component, classifying it definitively as a vector quantity. Common mistake: Grouping directional field quantities together with scalar properties like charge or potential.
The photocell works on the principle of the
Options A, B, and D misrepresent how light interacts with materials in electronic switching devices. A photocell functions based on the photoelectric effect, where incoming light radiation triggers the emission of electrons from a sensitive surface. Common mistake: Confusing the emission of electrons by light with proton emission or thermal electron processes.
When an atom loses or gains a charge, it becomes
Options B, C, and D are subatomic particles rather than charged atomic entities. When an atom either acquires or sheds electrical charges, it transforms into an ion, becoming a cation if positive or an anion if negative. Common mistake: Confusing the definition of an atomic ion with elementary particles like protons or electrons.
Which of the following characteristics of a wave is used in the measurement of the depth of the sea?
Options A, C, and D represent valid wave phenomena, but they are not used for ranging or distance calculations like mapping ocean floors. Sonar equipment determines sea depth by emitting sound waves and measuring the time it takes for their reflection to return from the ocean floor. Common mistake: Confusing wave bending or spreading properties with echo reflection.
Which of the following are produced after a nuclear fusion process? I. One heavy nucleus II. Neutrons III. Protons IV. Energy
A student might pick options A, B, or D by incorrectly assuming protons or neutrons are primary guaranteed products of every fusion reaction. Nuclear fusion involves merging lighter nuclei together to generate a single heavier nucleus accompanied by a massive release of energy resulting from mass defect. Common mistake: Assuming free nucleons like individual protons must always be listed as fusion products.
Two similar kettles containing equal masses of boiling water are placed on a table. If the surface of one is highly polished and the surface of the other is covered with soot, which of the following observations is correct?
Options A, B, or D are incorrect because polished and sooty surfaces behave very differently regarding thermal radiation. The kettle coated with soot features a black, non-reflective surface that acts as an excellent radiator of heat, causing it to cool down much faster via radiation than the reflective, polished kettle. Common mistake: Assuming conduction or convection is the primary cooling driver for surface-colored vessels.
Now practice in exam mode
You've studied the answers — now test yourself under real exam conditions with the timer running.
Start JAMB Physics 2015 QuizStudy JAMB Physics offline — no data needed
Get the JAMB app for Physics and every other subject — practice anywhere, even with no internet connection.