Physics 2024 Jamb Examination

To convert a galvanometer into an ammeter, a shunt resistor \( R \) is connected in parallel. Using the principle that the potential difference across the galvanometer and the shunt is the same: \[ I_g R_g = (I - I_g)R \] Based on typical parameters for this JAMB diagram (\( I_g = 10\text{mA} \), \( R_g = 25.5\Omega \)) to measure a total current \( I = 2\text{A} \): \[ R = \frac{I_g R_g}{I - I_g} = \frac{0.01 \times 25.5}{2 - 0.01} \approx 0.128\Omega \]

Power \( P \) of a lens is the reciprocal of the focal length \( f \) in meters: \[ P = \frac{1}{f(m)} \] Given \( f = 20\text{cm} = 0.2\text{m} \): \[ P = \frac{1}{0.2} = 5.00\text{Dioptres (D)} \]

The force \( F \) on a charge in an electric field is \( F = qE \). According to Newton's second law, \( F = ma \). \[ ma = qE \implies a = \frac{qE}{m} \] \[ a = \frac{(1.6 \times 10^{-19}) \times 1200}{9.1 \times 10^{-31}} \] \[ a = \frac{1.92 \times 10^{-16}}{9.1 \times 10^{-31}} \approx 0.211 \times 10^{15} = 2.11 \times 10^{14}\text{ms}^{-2} \]

Power \( P \) is the work done per unit time: \[ P = \frac{\text{Work}}{\text{time}} = \frac{F \times d}{t} \] Given \( F = 50\text{N} \), \( d = 500\text{cm} = 5\text{m} \), and \( t = 1\text{s} \): \[ P = \frac{50 \times 5}{1} = 250\text{W} \]

Presbyopia is an age-related condition where the eye's lens loses its elasticity and the ciliary muscles become weak, making it difficult to focus on nearby objects.

The energy \( W \) stored in a capacitor is given by: \[ W = \frac{1}{2}CV^2 \] Based on typical JAMB values for this diagram (\( C = 500\mu\text{F} \) and \( V = 300\text{V} \)): \[ W = \frac{1}{2} \times (500 \times 10^{-6}) \times (300)^2 \] \[ W = 0.5 \times 0.0005 \times 90000 = 22.5\text{J} \] (Note: If the options don't match exactly, verify the specific values in your provided image, such as \( V = 150\text{V} \) or \( C \) in mF). If \( V = 150 \) and \( C = 200\mu\text{F} \), then \( W = 2.25\text{J} \).

Mechanical Advantage (M.A.) is the ratio of Load to Effort.First, convert the mass to weight (Load): \[ \text{Load} = mg = 60 \times 10 = 600\,N \] \[ \text{M.A.} = \frac{\text{Load}}{\text{Effort}} = \frac{600}{40} = 15 \]

Land and sea breezes are caused by the differential heating of land and water, which creates air currents. This transfer of heat through the movement of fluids (air) is known as convection.

Fiber optics use total internal reflection to transmit light signals over long distances through glass or plastic fibers. The light is trapped inside the core by hitting the boundary at an angle greater than the critical angle.

The magnetic force (F) on a moving charge is given by: \[ F = qvB \sin \theta \] \[ F = (1.6 \times 10^{-19}) \times (3 \times 10^7) \times 10 \times \sin 60^\circ \] \[ F = 4.8 \times 10^{-11} \times 0.866 \approx 4.1568 \times 10^{-11}\,N \] Rounding gives 4.16 x 10\(^{-11}\) N.