2024 - JAMB Physics Past Questions and Answers - page 2

Here's the breakdown:* The Key Concept: The color of an object is determined by the wavelengths of light it reflects. Objects absorb most wavelengths and reflect specific ones.* Red Light and a Red Shirt: A red shirt reflects red light. When viewed under red light, the shirt still reflects red light, making it appear red. However, when the shirt is exposed to white light, the shirt absorbs all other colors except for red.* Why the Answer is D: The red shirt under red light, absorbs other colors and reflects red.

The question asks why water is unsuitable as a thermometric liquid. Let's analyze the provided statements:* I. It wets glass: This is a significant issue. If water wets the glass of the thermometer, it will cling to the sides of the glass tube, making it difficult to read the temperature accurately. This is because the meniscus of the water will change, affecting the level reading.* II. It needs to be coloured: While coloring water might be done for better visibility, it's not a fundamental reason why water is unsuitable. Other thermometric liquids can also be colored.* III. It has a low density: While this is true to a degree (compared to some other liquids), it is not a primary reason for its unsuitability. The main issue is its ability to wet glass.Therefore, the most significant reason water is unsuitable is its wetting of glass.

Here's how to solve the problem:

1. Understand the forces: The tension in the rope has two components: a horizontal component that pulls the body along the surface and a vertical component. We are given the horizontal component (effective force).
2. Use trigonometry: The angle given is 30 degrees to the vertical, so the angle to the horizontal is 90 - 30 = 60 degrees. The horizontal component of the tension (Fx) can be written as: Fx = T * cos(θ), where T is the tension and θ is the angle between the rope and the horizontal.
3. Solve for Tension (T): We know Fx = 15 N and θ = 60 degrees. Therefore: *

The mass of a substance deposited during electrolysis is directly proportional to its chemical equivalent. This is a statement of Faraday's second law of electrolysis. The chemical equivalent is defined as the atomic weight divided by the valency.

Here's how to solve the problem:1. Calculate the volume of the cube: * Volume (V) = side * side * side * V = 1.5 cm * 1.5 cm * 1.5 cm = 3.375 cm³2. Convert the volume from cm³ to m³: * 1 m = 100 cm * 1 m³ = (100 cm)³ = 1,000,000 cm³ * V = 3.375 cm³ * (1 m³ / 1,000,000 cm³) = 3.375 x 10⁻⁶ m³3. Use the density formula to find the mass: * Density (ρ) = mass (m) / volume (V) * Rearrange the formula to solve for mass: m = ρ * V * m = 2700 kg/m³ * 3.375 x 10⁻⁶ m³ = 0.0091125 kg4. Convert the mass from kg to grams: * 1 kg = 1000 g * m = 0.0091125 kg * 1000 g/kg = 9.1125 g5. Round to the nearest tenth: * m ≈ 9.1 g

The correct answer is Presbyopia. Here's why:* Presbyopia: This is a condition associated with aging where the lens of the eye loses its flexibility, and the ciliary muscles weaken. This makes it difficult to focus on near objects.* Spherical aberration: This is a defect of the lens where light rays passing through the lens are not focused at a single point.* Astigmatism: This is a condition where the cornea or lens has an irregular shape, causing blurred vision at all distances.* Myopia: Also known as nearsightedness, this is a condition where distant objects appear blurry because the eye focuses images in front of the retina.

The question describes a body moving in a straight line from point P to point Q.* Translational motion refers to movement in a straight line.* Rotational motion involves spinning around an axis.* Simple harmonic motion is oscillatory motion.* Circular motion involves movement in a circle.Since the motion is linear and changes position, the correct answer is translational motion.

The relative humidity is calculated using the following formula:

Relative Humidity = (SVP at dew point / SVP at air temperature) * 100%

Here's how to solve the problem:

1. Identify the SVP at the dew point and air temperature:

   • SVP at dew point (7°C) = 7.3 mmHg
   • SVP at air temperature (33°C) = 13.5 mmHg

2. Apply the formula: Relative Humidity = (7.3 mmHg / 13.5 mmHg) * 100%

3. Calculate the result: Relative Humidity ≈ 54.07%

4. Round to the nearest whole number:

The frequency (f) of a sonometer's fundamental note is directly proportional to the square root of the tension (T) in the wire. Mathematically, this is expressed as:f ∝ √TIf the tension is increased four times (4T), the new frequency (f') can be calculated as follows:f' ∝ √(4T)f' ∝ 2√TSince the original frequency (f) is proportional to √T, and we know f = 50Hz:f' = 2ff' = 2 * 50 Hzf' = 100 Hz

Air friction, also known as air resistance or drag, opposes the motion of an object through the air.* Streaming: Streamlining involves shaping an object to reduce its surface area exposed to the airflow and create a more aerodynamic shape. This minimizes the contact area between the object and the air molecules, thereby reducing friction.* Lubricating: Lubrication is primarily used to reduce friction between solid surfaces in contact with each other. It's not directly applicable to reducing air friction.* Propeller: A propeller is used to generate thrust, propelling an object forward through the air. It does not directly reduce air friction; rather, it helps overcome it.* Polishing: Polishing can reduce surface roughness, which can minimize friction between solid surfaces. However, it doesn't directly address the air friction.