This question is about waves in the electromagnetic (e.m.) spectrum - Edexcel - GCSE Physics Combined Science - Question 6 - 2022 - Paper 1

To find the wavelength, we use the formula:

ext{Wavelength} = rac{v}{f}

where:

• $v = 3.00 \times 10^8 ext{ m/s}$ (speed of light)
• $f = 2.45 \times 10^9 ext{ Hz}$ (frequency in Hertz)

Substituting in the values:

$$\lambda = \frac{3.00 \times 10^8}{2.45 \times 10^9} \approx 0.122 \text{ m}$$

Thus, the wavelength of the microwaves is approximately 0.122 m.

To find the total energy supplied to the oven, we apply the efficiency formula:

$$\text{Total Energy Supplied} = \frac{\text{Energy Used}}{\text{Efficiency}}$$

Given:

• Energy Used = 42000 J
• Efficiency = 0.55

Substituting the values:

$$\text{Total Energy Supplied} = \frac{42000}{0.55} \approx 76363.64 ext{ J}$$

Therefore, the total amount of energy that must be supplied to the oven is approximately 76363.64 J.

X-rays are high frequency electromagnetic waves used in medical imaging to diagnose issues such as broken bones or to treat certain conditions like cancer. They are high energy waves that can ionize atoms, making them potentially harmful.

In contrast, radio waves have a low frequency and long wavelength, making them non-ionizing with low energy. They are primarily used for communication purposes such as broadcasting television and radio signals.

The production of X-rays involves electrons transitioning between energy levels, emitting high-energy radiation as they fall back to a lower energy state. Conversely, radio waves are produced by oscillating electrons in circuits, which creates alternating currents that correspond to specific frequencies.