Read the following passage and answer the accompanying questions - Leaving Cert Physics - Question 11 - 2016

To draw the ray diagram:

1. Place the object (e.g., an arrow) within the focal point of the converging lens.
2. Draw one ray from the top of the object directly to the lens that travels straight through and another ray from the top of the object that goes through the lens and diverges away.
3. Extend the diverging ray backward to intersect the line of the straight ray, where the virtual image is formed.

Wavelength is defined as the distance between two consecutive crests or troughs of a wave. It is a measure of how long one cycle of the wave is and is usually denoted by the symbol $\lambda$.

The colours observed by Newton in order from least to most refracted are: red, orange, yellow, green, blue, indigo, violet.

Young might have produced coherent sources of light by using:

1. Two double slits, allowing wavefronts to originate from each slit and maintain a constant phase difference.
2. A single source of light passed through a beam splitter to create two coherent beams.

To calculate the energy:

1. Use the formula:

$E = \frac{hc}{\lambda}$

where:

• $h = 6.63 \times 10^{-34} \text{ J s}$ (Planck's constant)
• $c = 3.00 \times 10^8 \text{ m/s}$ (speed of light)
• $\lambda = 510 \text{ nm} = 510 \times 10^{-9} \text{ m}$

Calculating gives:

$E = \frac{(6.63 \times 10^{-34})(3.00 \times 10^8)}{510 \times 10^{-9}} = 3.89 \times 10^{-19} \text{ J}$

Electrons gain energy to move to higher energy levels. They do this when they absorb energy from an external source, such as heat or light. When electrons return to lower energy levels, they emit energy in the form of light or electromagnetic radiation, creating distinct lines in the spectrum known as line emission spectra.

1. Photons have no mass, while electrons have mass.
2. Photons have no charge, whereas electrons carry a negative charge.