The dispersion of light would result in which of the following phenomena?
Dispersion of light occurs when white light separates into its component colors due to different wavelengths refracting at different angles, forming a rainbow.
The best color of shirt to be worn on a bright noon day is
White color reflects most sunlight, keeping the wearer cooler compared to darker colors that absorb more heat.
The image formed when an object is placed between the focus and centre of a converging lens is
For a converging lens, an object between F and 2F produces a real, inverted, and magnified image beyond 2F.
For a charged body moving in an electric and magnetic crossed field, the ratio of the electric field intensity, E to the magnetic flux density, B is known as
The ratio E/B gives the velocity at which the electric force balances the magnetic force, selecting particles of that speed in a velocity selector.
A note, K from a keyboard has an amplitude of 0.5cm and frequency 2000Hz. Another note, M from a guitar has an amplitude of 1.5cm and frequency 2000Hz. Which of the following statements is true if the two notes are compared?
Loudness depends on amplitude; higher amplitude (1.5cm for M) means M is louder. Same frequency means same pitch, and timbre differs due to different instruments.
A simple pendulum of length 0.8m is set oscillating on a planet. If the pendulum completes 20 oscillations in 60s, calculate the acceleration due to gravity on this planet. [π = 3.14]
Time period T = 60s / 20 = 3s. T = 2π√(L/g), so g = 4π²L / T² = 4*(3.14)²*0.8 / 9 ≈ 3.0 ms⁻².
A liquid of mass 2kg at 61°C is kept in a lagged vessel. If another 2kg of the same liquid at 21°C is added to the liquid in the vessel, calculate the final temperature of the mixture
Assuming no heat loss, heat lost = heat gained: 2m c (61 - θ) = 2m c (θ - 21), so θ = (61 + 21)/2 = 41°C.
If two bodies, A and B are each in thermal equilibrium with another body C, then the three bodies are in thermal equilibrium with each other. This is the statement of
The zeroth law defines temperature and thermal equilibrium transitively, allowing thermometers to work.
What is the S.I unit of electric charge?
The S.I unit of electric charge is the coulomb (C), defined as the charge transported by 1 ampere in 1 second.
A body of mass 5kg falls freely from rest. Calculate the kinetic energy after 2 seconds [g = 10ms⁻²]
Velocity after 2s, v = gt = 10*2 = 20 ms⁻¹. KE = (1/2)mv² = 0.5*5*400 = 100 J.
The speed of light in medium A of refractive index 1.5 is 2.0 × 10⁸ms⁻¹. Determine the speed of light in medium B of refractive index 1.2
Speed in vacuum c = n_A * v_A = 1.5 * 2.0e8 = 3.0e8 ms⁻¹. Then v_B = c / n_B = 3.0e8 / 1.2 = 2.5e8 ms⁻¹.
The wavelength of a sound note travelling with a speed of 360ms⁻¹ is 600m. Determine the period of the note
Period T = λ / v = 600 / 360 ≈ 1.667 s.
In which of the following levers is the effort applied between the load and the fulcrum?
Sugar tongs are a class 3 lever where the effort is applied between the fulcrum and the load.
A current of 2A flows through a resistor of 5Ω. Calculate the power dissipated in the resistor
Power P = I²R = 2² * 5 = 20 W.
Calculate the potential difference across a 10Ω resistor when a current of 0.5A flows through it
V = IR = 0.5 * 10 = 5 V.
Which of the statements is correct about the nucleus of an atom? I. is centrally located in the atom. II. contains the nucleons and electrons. III. is positively charged due to the protons. IV. decays when there is instability inside.
The nucleus is central (I), positively charged due to protons (III), and decays if unstable (IV). It contains nucleons (protons and neutrons), not electrons (II wrong).
A radioactive element of mass 16g was isolated and stored. It was discovered that after 40 days only 1g of the element remained undecayed. Calculate the half-life of the element
From 16g to 1g is 4 half-lives (16→8→4→2→1). Time = 40 days, so half-life = 40/4 = 10 days.
Which of the following reasons explains why the walls and ceilings of a standard concert hall are usually covered with perforated pads? To
Perforated pads absorb sound waves, reducing echoes and reverberation for clearer acoustics.
A bucket of water of mass 10kg is swung in a vertical circle of radius 1.2m. While at the lowest position of the swing, its speed is 5ms⁻¹. Determine the tension in the string (g = 10ms⁻²)
At lowest point, T - mg = mv²/r, T = mg + mv²/r = 10*10 + 10*25/1.2 = 100 + 208.3 ≈ 308.3 N.
A man's near point is 30cm. Which of the following eye defects is the man likely to suffer from?
Hypermetropia (farsightedness) has a near point farther than normal (25 cm), so 30 cm indicates hypermetropia.
White light can be produced by a combination of I. magenta, yellow and cyan. II. red, blue and green. III. magenta and green. IV. yellow, red and green.
White light is produced by additive primary colors: red, green, and blue (II). The others do not combine to white.
What is the S.I unit of power?
The S.I unit of power is the watt (W), which is joule per second.
Which of the following statements about stationary wave is not true?
In a stationary wave, particles between adjacent nodes are out of phase (180°), not in phase.
In a pipe closed at one end and open at the other end, the overtones that accompany the fundamental frequency are
A closed pipe produces only odd harmonics (overtones) due to the boundary conditions.
A radioactive substance of mass 512.0g decays to 64.0g. Determine the number of half-life involved in the decay
512 / 64 = 8, and 2³ = 8, so 3 half-lives.
Two waves will interfere destructively if the path difference between the waves is
Destructive interference occurs when path difference is an odd multiple of λ/2, such as λ/2.
A radioactive substance of mass 16g at GMT: 13:00 hour was received at a hospital. The half-life of the substance is 2 hours. Determine the fraction of the substance left after 4 hours
After 4 hours = 2 half-lives, fraction left = (1/2)² = 1/4.
The mechanical advantage of a hospital bed is 1.71. Which of the following statements is correct? The effort applied
MA = load/effort = 1.71 > 1, so effort < load (weight).
A sound from a microphone is transformed to electrical energy. The type of energy stored is
The microphone converts sound energy into electrical energy, which is then stored or transmitted.
Calculate the velocity ratio of an inclined plane inclined at 45° to the horizontal
VR = 1 / sinθ = 1 / sin45° = 1 / (√2/2) ≈ 1.41.
The angle between the velocity vector and the acceleration vector for a body in uniform circular motion is
In uniform circular motion, acceleration is centripetal, perpendicular to velocity, so 90°.
The S.I unit of the power consumed by a system is
Power is measured in watts (W), the S.I unit for rate of energy transfer.
The secondary coil of a transformer has more turns than the primary coil. If the number of turns in the secondary coil is 500 and the primary coil is 250, the step-up transformer is
Turns ratio N_s : N_p = 500 : 250 = 2:1, step-up since N_s > N_p.
Which of the following statements is correct about the nucleus of an atom? It
The nucleus contains protons (positive charge) and neutrons, making it positively charged.
A radium nuclide decays by emitting alpha particle as shown below: ²²⁶₈₈Ra → X + ⁴₂He. Determine the daughter nuclide
Mass: 226 - 4 = 222, Atomic number: 88 - 2 = 86, so ²²²₈₆X (radon).
A bullet of mass 0.025kg moves at 250ms⁻¹. Calculate its deBroglie wavelength [h = 6.63 × 10⁻³⁴ Js]
λ = h / (mv) = 6.63e-34 / (0.025 * 250) = 6.63e-34 / 6.25 ≈ 1.06 × 10⁻³⁴ m.
An electron moving with a speed of 5.0 × 10⁵ms⁻¹ enters a uniform magnetic field at 90°. Calculate the magnitude of the magnetic force on the electron if the magnetic field intensity is 0.25T [e = 1.6 × 10⁻¹⁹C]
F = q v B sin90° = 1.6e-19 * 5.0e5 * 0.25 = 2.0 × 10⁻¹⁴ N.
A beam of light which appears to come from a point in space is said to be
A divergent beam appears to originate from a virtual point source behind the observer.
A sound wave made up of large number of unrelated frequencies superimposed on each other is called
Noise consists of a random superposition of many unrelated frequencies, unlike musical notes with harmonics.
A boy pushes a box of mass 80kg along a horizontal floor with a force of 200N. If the box is pushed with a uniform velocity, what is the coefficient of friction between the box and the floor? [g = 10ms⁻²]
For uniform velocity, F = frictional force = μ mg, so μ = F / (mg) = 200 / (80 * 10) = 0.25.
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