1.
A soap bubble that is 250 nm thick is illuminated by white light, and the refraction index of the soap film is 1.36. Which colors appear strong in the reflected light?
Correct Answer
D. Blue (450-495 nm)
Explanation
Soap bubbles exhibit interference effects due to the thin film of soap. When white light is incident on the soap bubble, it undergoes multiple reflections and interference within the thin film. The thickness of the film determines which colors are reinforced or canceled out. In this case, the soap bubble is 250 nm thick, which corresponds to the wavelength range of blue light (450-495 nm). Therefore, blue light will experience constructive interference and appear strong in the reflected light. The other colors mentioned, red, yellow, and orange, have wavelengths outside the range of the soap bubble's thickness and will experience destructive interference, resulting in weaker or no reflection.
2.
What is the thickness of an anti-reflective coating (n = 1.3) that is put on a lens (n = 1.5) to minimize reflection at a wavelength of 550 nanometers?
Correct Answer
A. 550nm
3.
A double-slit interference experiment is made in a chamber that can be filled with water. Using a monochromatic light source, an interference pattern is observed when the chamber is open to air. What happens to the interference fringes when the chamber is filled with water?
Correct Answer
B. The interference fringes move closer together.
Explanation
When the chamber is filled with water, the interference fringes move closer together. This is because the speed of light in water is slower than in air. As a result, the wavelength of the light decreases when it passes through water. Since the distance between the fringes is determined by the wavelength of the light, the fringes appear closer together in water compared to when the chamber is open to air.
4.
Electromagnetic waves transfer energy from the source of the waves to _________.
Correct Answer
C. Absorber
Explanation
Electromagnetic waves transfer energy from the source of the waves to an absorber. An absorber is a material or object that absorbs the energy carried by the waves, converting it into another form, such as heat or electrical energy. This process allows the energy of the waves to be utilized or dissipated, depending on the specific application or circumstances.
5.
Radio waves have the
Correct Answer
A. Lowest frequency
Explanation
Radio waves have the lowest frequency among all the electromagnetic waves. Frequency refers to the number of complete cycles of a wave that occur in one second. Since radio waves have the lowest frequency, they have the longest wavelength. This means that the distance between two consecutive peaks or troughs of the wave is greater for radio waves compared to other types of waves such as visible light or X-rays.
6.
Our eyes only detect
Correct Answer
D. Visible light
Explanation
Our eyes only detect visible light, which is a small portion of the electromagnetic spectrum. Visible light consists of different colors that range from red to violet, each corresponding to a specific frequency. Our eyes have specialized cells called cones that are sensitive to these frequencies and enable us to perceive the different colors in our environment. While other parts of the electromagnetic spectrum, such as infrared or ultraviolet, exist, our eyes are not capable of detecting them.
7.
In transverse waves, the oscillations are ________ to the direction of energy transfer.
Correct Answer
B. Perpendicular
Explanation
In transverse waves, the oscillations are perpendicular to the direction of energy transfer. This means that the particles of the medium vibrate or move up and down or side to side, while the wave itself moves forward. This perpendicular relationship between the oscillations and the direction of energy transfer is a characteristic feature of transverse waves.
8.
Which of the following electromagnetic waves have the shortest wavelengths and highest frequencies?
Correct Answer
A. Gamma rays
Explanation
Gamma rays have the shortest wavelengths and highest frequencies among the given options. Gamma rays are a form of electromagnetic radiation, similar to X-rays but with even higher energy. They have the shortest wavelengths, ranging from less than one picometer to about 10 femtometers, and the highest frequencies, typically above 10 exahertz. Gamma rays are produced by nuclear reactions, radioactive decay, and high-energy particle interactions. They are often used in medical imaging, cancer treatment, and sterilization processes due to their ability to penetrate matter and ionize atoms.
9.
Which electromagnetic waves are used in ovens and cell phone communications?
Correct Answer
D. Microwaves
Explanation
Microwaves are used in ovens and cell phone communications. In ovens, microwaves are used to heat and cook food by generating heat directly within the food. In cell phone communications, microwaves are used to transmit and receive signals between cell towers and mobile devices. Microwaves have the ability to penetrate through walls and other obstacles, making them suitable for long-distance communication. Additionally, microwaves have a shorter wavelength compared to other electromagnetic waves, allowing for higher data transmission rates in cell phone communications.
10.
Which statement accurately describes a step in the generation of electromagnetic waves?
Correct Answer
A. A changing current I creates a changing magnetic field B, which induces an electric field E.
Explanation
When there is a changing current I, it generates a changing magnetic field B according to Ampere's law. This changing magnetic field then induces an electric field E according to Faraday's law of electromagnetic induction. This process is the fundamental step in the generation of electromagnetic waves, as the changing electric and magnetic fields propagate through space, creating a self-sustaining wave.