This question is about waves in the electromagnetic (e.m.) spectrum - Edexcel - GCSE Physics - Question 9 - 2022 - Paper 1

To calculate the wavelength ( λ ) of the microwaves, we can use the formula:

$$λ = \frac{c}{f}$$

where:

• $c$ = speed of light = $3.00 × 10^8 m/s$
• $f$ = frequency = $2.45 × 10^9 Hz$

Plugging in the values:

$$λ = \frac{3.00 × 10^8 m/s}{2.45 × 10^9 Hz} ≈ 0.1224 m$$

Thus, the wavelength is approximately 0.1224 m.

To find the total energy supplied to the oven, we can use the formula for efficiency:

$$e_{total} = \frac{e_{useful}}{efficiency}$$

where:

• $e_{useful} = 42,000 J$
• $efficiency = 0.55$

Calculating:

$$e_{total} = \frac{42000 J}{0.55} ≈ 76363.64 J$$

Therefore, the energy supplied to the oven is approximately 76363.64 J.

X-rays and radio waves are both types of electromagnetic radiation but differ in their uses and production methods:

Uses:

1. X-rays are primarily used in medical imaging to view the inside of the body for diagnostic purposes.
2. Radio waves are utilized for communication, including broadcasting audio signals and data transmission in wireless networks.

Production Methods:

1. X-rays are generated when electrons within atoms lose energy during transitions to lower energy levels, emitting high-energy photons.
2. Radio waves are produced by electrons oscillating in antennas, often as a result of an alternating current.

Conclusion:

• X-rays have higher frequencies and energy than radio waves, making them suitable for penetrating materials like human tissue.
• Radio waves are less energetic, allowing them to carry signals over long distances without substantial loss.