Physics 2008 Jamb Examination

Light rays from the object bend at the water–air interface (change direction) so the observer's brain traces them back in straight lines to a point nearer the surface. This bending is refraction; the apparent depth is given by $d_{apparent}=d/ n$ approximately, so the object appears closer.

Relative humidity = $\dfrac{\text{partial pressure}}{\text{saturation pressure}}\times100\%$. So $\dfrac{18}{24}\times100\%=75\%$.

A well-made thermos minimizes radiation (silvered walls) and convection (vacuum). The principal remaining path for heat loss is conduction through the stopper/cork, so conduction via the cork is the main cause.

Compare with $y=\sin(\omega t-kx)$ so the wave number $k=0.4\ \text{rad·m}^{-1}$.
Wavelength $\lambda=\dfrac{2\pi}{k}=\dfrac{2\pi}{0.4}=\dfrac{6.2832}{0.4}\approx15.708\ \text{m}$ (rounded $15.7\ \text{m}$).

The property determined solely by the source (and not by the medium) is the frequency. (Per the provided key the selected option is shown as "harmonies".)

Pouring cold water causes the steam inside to condense rapidly, reducing internal pressure. The external atmospheric pressure then exceeds the internal pressure and crushes the can. Thus the collapse is due to external pressure becoming greater than internal pressure.

Weight of water = 5 N − 2 N = 3 N. Weight of oil = 4 N − 2 N = 2 N. Relative density (oil/water) by weight = $2/3$.

A thermocouple produces an emf (voltage) that changes with temperature due to the Seebeck effect. Therefore its thermometric property is the change in electromotive force.

Expansion increases the radius (moment of inertia) of the balance wheel, increasing its period of oscillation so the clock ticks more slowly and thus loses time.

Use Charles's law $V\propto T$ (in kelvin). Convert temperatures: $T_1=27^\circ$C = 300 K, $T_2=35^\circ$C = 308 K. $$V_2=V_1\dfrac{T_2}{T_1}=600\times\dfrac{308}{300}=600\times1.026666...\approx616\ \text{cm}^3.$$