Read the following passage and answer the accompanying questions - Leaving Cert Physics - Question 11 - 2015

For an a.c. supply, the voltage-time graph is a sinusoidal wave, representing alternating voltage over time. It oscillates above and below zero.

For a d.c. supply, the voltage-time graph is a straight line that remains constant over time, indicating a steady voltage level.

Electromagnetic induction refers to the process of generating an electromotive force (emf) in a circuit by changing the magnetic flux through that circuit. When a magnetic field around a conductor changes, it induces an electric current in the conductor.

A transformer does not work with direct current because direct current does not produce a varying magnetic field. Transformers rely on the alternating change in magnetic flux to induce voltage; without this change, no current is induced in the secondary coil.

Using low voltage for electricity transmission is inefficient because it requires a large current to deliver the same amount of power, which leads to greater resistive losses as heat. Higher current in the wires causes substantial energy loss over long distances.

The rms (root mean square) voltage can be calculated using the formula:

V_{rms} = rac{V_{peak}}{ ext{√2}}

Substituting the given value, we have:

V_{rms} = rac{321 ext{ V}}{ ext{√2}} ≈ 227 ext{ V}

It is necessary to use the rms voltage when comparing a.c. and d.c. electricity because the rms value provides a measure of the effective voltage that delivers the same power as d.c. This allows for accurate comparisons in terms of power output, as ac and dc have different waveforms.

Advantage: Electric cars have fewer carbon emissions compared to traditional gasoline vehicles, contributing to reduced air pollution.

Disadvantage: Electric cars can have a short range and require expensive batteries, which may be a limitation for some users.