A negative magnification for a mirror means that the image is inverted, and the mirror could be either concave or convex the image is inverted, or the mirror is concave. The image is inverted, mirror could be either concave or convex. The image is upright, and the mirror is convex the image is inverted, and the mirror is convex. An object is placed in front of a thin lens. Which statement, are correct in describing the image formed by the lens? (There could be more than one correct choice.) If the lens is convex, the image must be real. If the image is real, then it is also inverted. If the image is real, then it is also upright. If the lens is convex, the image will never be virtual. If the lens is concave, the image must be virtual. When a beam of light, originally traveling in air, enters a piece of glass having an index of refraction of 3/2 its frequency is unaffected. Is reduced to 2/3 its original value. Increases by a factor of 3/2. The index of refraction of a type of glass is 1.50, and the index of refraction of water is 1.33. If light enters water from this glass, the angle of refraction will be equal to the angle of incidence. Less than the angle of incidence. Greater than the angle of incidence. Which of the following terms describe lenses that are thinner at the center than at the edges? (There could be more than one correct choice.) Concave lenses converging lenses diverging lenses convex lenses you may have seen ambulances on the street with the letters of the word AMBULANCE written on the front of them, in such a way as to appear correctly when viewed in your car’s rear-view mirror. (See the figure.) How do the letters appear when you look directly at the ambulance (not through the mirror)?
The Correct Answer and Explanation is :
Correct Answers and Explanations
- If the lens is convex, the image must be real.
- Incorrect. The image formed by a convex lens can be either real or virtual depending on the position of the object. If the object is beyond the focal point, the image will be real and inverted. If the object is closer to the lens than the focal point, the image will be virtual and upright.
- If the image is real, then it is also inverted.
- Correct. A real image formed by a lens is always inverted relative to the object. This happens because light rays converge to form a real image, and the rays on opposite sides of the object cross paths.
- If the image is real, then it is also upright.
- Incorrect. Real images are inverted, not upright.
- If the lens is convex, the image will never be virtual.
- Incorrect. Convex lenses can form virtual images when the object is placed inside the focal length. In this case, the light rays diverge, and the image formed is virtual and upright.
- If the lens is concave, the image must be virtual.
- Correct. A concave lens always forms a virtual image. For any object, the rays diverge, and the image appears to be formed on the same side as the object.
- When a beam of light, originally traveling in air, enters a piece of glass having an index of refraction of 3/2, its frequency is unaffected.
- Correct. The frequency of light does not change when it moves from one medium to another, but its speed and wavelength do change. The frequency is determined by the source of the light and remains constant across media.
- The index of refraction of a type of glass is 1.50, and the index of refraction of water is 1.33. If light enters water from this glass, the angle of refraction will be:
- Less than the angle of incidence. Since the light is moving from a medium with a higher index of refraction (glass, 1.50) to one with a lower index of refraction (water, 1.33), the angle of refraction will be smaller than the angle of incidence according to Snell’s Law.
- Which of the following terms describe lenses that are thinner at the center than at the edges?
- Concave lenses and diverging lenses. Concave lenses are thinner at the center than at the edges, and they cause light rays to diverge.
Explanation of “AMBULANCE” in the Rear-View Mirror
When you see an ambulance with the word “AMBULANCE” written in reverse on the front, the letters appear normally when viewed in the rear-view mirror. This happens because a rear-view mirror is a concave mirror, which diverges light rays that are reflected back toward the observer. A concave mirror has the property of reversing the image it forms, such that text or objects placed in front of the mirror are reflected in a way that they appear the correct way around.
When you look directly at the ambulance (not through the mirror), the letters appear backwards, since the text is intentionally printed in reverse. In a concave mirror, the letters are reflected such that the mirror gives you a virtual image that looks correctly oriented to you.
So, the word “AMBULANCE” is printed in reverse so that, when viewed through the rear-view mirror (which is a concave mirror), the letters appear upright to drivers in their cars.