Physics 2016 Jamb Examination

Saturation is a state of dynamic equilibrium. In an enclosed container, molecules are constantly escaping from the liquid surface into the space above (vaporisation) and returning from the vapour phase back into the liquid (condensation). When the rate at which molecules escape the liquid exactly equals the rate at which they return, the vapour is said to be saturated. At this point, the pressure exerted by the vapour remains constant at a given temperature, known as the saturated vapour pressure.

The refractive index (\(n\)) of a medium can be defined as the ratio of the real depth to the apparent depth of an object viewed through that medium. The formula is given by:\[ n = \frac{\text{Real Depth}}{\text{Apparent Depth}} \]Given:\[ n = 1.33 \]\[ \text{Apparent Depth} = 1.00\text{m} \]Rearranging to solve for Real Depth:\[ \text{Real Depth} = n \times \text{Apparent Depth} \]\[ \text{Real Depth} = 1.33 \times 1.00 = 1.330\text{m} \]

Rectilinear propagation of light is the property of light that describes its travel in straight lines. When an opaque object is placed in the path of light, the straight-travelling rays are blocked, creating a dark region behind the object known as a shadow. Large-scale versions of this phenomenon, such as when the Moon blocks sunlight from reaching the Earth, result in eclipses. If light could easily bend around corners (significant diffraction), distinct shadows and eclipses would not form as they do.

This involves the additive mixing of light. Magenta is a secondary colour of light produced by mixing the primary colours Red and Blue (\(M = R + B\)). When you add Green light to Magenta light, you are essentially combining all three primary colours of light together:\[ \text{Magenta} + \text{Green} = (\text{Red} + \text{Blue}) + \text{Green} = \text{White} \]The combination of the three primary colours (Red, Green, and Blue) at equal intensities results in white light.

Standard moving coil instruments (like moving coil ammeters and galvanometers) rely on a magnetic field that interacts with the direction of the current. In an alternating current (a.c.) circuit, the current changes direction rapidly, causing the needle to vibrate about the zero mark rather than giving a steady reading. A hot wire ammeter works on the principle of the heating effect of current (\(H = I^2Rt\)). Since the heating effect is independent of the direction of the current, it can accurately measure the effective (r.m.s) value of alternating current.

All electromagnetic waves (light, radio, X-rays, etc.) are transverse waves because the electric and magnetic fields oscillate perpendicular to the direction of energy transfer. Statement B is incorrect because mechanical transverse waves (like those on a string) *do* require a medium; only electromagnetic waves can travel through a vacuum. Statement C is the definition of a transverse wave, not a longitudinal one. Statement D is incorrect because mechanical waves can be either longitudinal (sound) or transverse (waves on a rope).

For any object to maintain a circular path, there must be a net force acting towards the centre of the circle; this is known as the centripetal force. In the case of a satellite, the gravitational pull of the Earth provides this necessary centripetal force. While 'centrifugal force' is often discussed, it is a 'fictitious' force or an inertial reaction perceived from within the rotating frame, not an actual force acting on the satellite to keep it in orbit. Therefore, the physical force maintaining the orbit is the centripetal force (gravity).

A manometer is a scientific instrument, typically consisting of a U-shaped tube containing a liquid (often mercury or water), used to measure the pressure of a fluid (liquid or gas). It works by showing the difference in pressure between two points, or between a system and the atmosphere. Atmospheric pressure specifically is measured by a barometer, and humidity is measured by a hygrometer.

According to Archimedes' Principle, the upthrust (buoyant force) exerted on a body immersed in a fluid is equal to the weight of the fluid displaced by the body. We are given the mass of the water displaced.
Given:
Mass of water displaced (\(m\)) = 3.7 kg
Acceleration due to gravity (\(g\)) \(\approx 10\text{ ms}^{-2}\)
The upthrust (U) is the weight of this displaced water:\[ U = m \times g \]\[ U = 3.7 \times 10 = 37.0\text{ N} \]The weight in air is irrelevant to finding the upthrust when the mass of displaced fluid is already known.

Impulse is defined as the product of a force and the time interval over which it acts. Newton's second law states that the force is equal to the rate of change of momentum:\[ F = \frac{mv - mu}{t} \]By multiplying both sides by the time (\(t\)), we get the impulse-momentum theorem:\[ F \times t = mv - mu \]Where \(mv - mu\) represents the change in momentum. While option B represents the force itself, the question asks for the impulse (the change in momentum), which is represented by \(mv - mu\).