James Clerk Maxwell, a Scottish physicist, is considered the greatest theoretical physicist of the nineteenth century - Leaving Cert Physics - Question 9 - 2018

A pair of complementary colours of light is Red and Cyan.

A magnetic field is a region around a magnetic material or a moving electric charge within which the force of magnetism acts. This field is represented by magnetic field lines that indicate the direction and strength of the magnetic force.

The magnetic field around a long straight current-carrying wire can be illustrated as concentric circles with arrows indicating the direction of the magnetic field lines. The direction of the magnetic field is given by the right-hand rule: if the thumb of the right hand points in the direction of the current, the fingers curl in the direction of the magnetic field.

The magnetic field inside a solenoid is uniform and parallel to the axis of the solenoid. Outside the solenoid, the magnetic field lines spread out. The direction of the magnetic field inside the solenoid can also be indicated using the right-hand grip rule: curling the fingers in the direction of the current flow through the coils, the thumb points in the direction of the magnetic field.

Faraday's law states that the induced electromotive force (emf) in any closed circuit is equal to the negative rate of change of magnetic flux through the circuit:
ext{emf} = -rac{d heta}{dt}

An experiment to demonstrate Faraday's law involves using a coil of wire and a magnet. When a magnet is moved toward the coil (or vice versa), an emf is induced in the coil, which can be detected using a galvanometer. The setup should ensure that the movement of the magnet relative to the coil is quick and that the orientation allows maximum change in magnetic flux.

To find the average emf induced, we can use the formula:
E = -rac{d heta}{dt}
where $d heta$ is the change in magnetic flux and $dt$ is the time interval. Given:

• Area $A = (0.2 ext{ m})^2 = 0.04 ext{ m}^2$
• Flux density $B = 50 ext{ mT} = 0.050 ext{ T}$
• Total change in flux:
  $ext{Flux} = B imes A = 0.050 imes 0.04 = 0.002 ext{ Wb}$
  Therefore,
  E = -rac{0.002}{(1/6)} = -0.012 ext{ V} = 0.012 ext{ V}

Light is detected in the retina of the eye, where photoreceptor cells (rods and cones) convert light into neural signals.

Two invisible parts of the electromagnetic spectrum that have shorter wavelengths than visible light are:

• Ultraviolet rays
• X-rays.