OAT Physics: Optics and Waves 5 β Questions and Answers
Question 1: In a single-slit diffraction pattern, the width of the central maximum is affected by:
- Only the wavelength of light
- Only the width of the slit
- Both the wavelength and the slit width (Correct answer)
- The index of refraction of the slit material
Correct answer: Both the wavelength and the slit width
The central maximum half-width is given by sinΞΈ = Ξ»/a, so it depends on both wavelength Ξ» and slit width a.
Question 2: An object is placed inside the focal point of a converging lens. The image formed is:
- Real, inverted, and enlarged
- Virtual, upright, and enlarged (Correct answer)
- Real, inverted, and reduced
- Virtual, inverted, and reduced
Correct answer: Virtual, upright, and enlarged
When the object is inside the focal length, a converging lens acts as a magnifying glass, producing a virtual, upright, and enlarged image.
Question 3: The electromagnetic spectrum from longest to shortest wavelength is ordered as:
- Radio, microwave, infrared, visible, UV, X-ray, gamma (Correct answer)
- Gamma, X-ray, UV, visible, infrared, microwave, radio
- Visible, infrared, microwave, radio, UV, X-ray, gamma
- Radio, visible, UV, X-ray, infrared, microwave, gamma
Correct answer: Radio, microwave, infrared, visible, UV, X-ray, gamma
From longest to shortest wavelength: radio > microwave > infrared > visible > ultraviolet > X-ray > gamma rays.
Question 4: Which of the following best describes polarization of light?
- Light waves oscillating in all planes perpendicular to propagation
- Light waves restricted to oscillate in a single plane (Correct answer)
- Light waves oscillating parallel to the direction of travel
- Light waves diffracting around obstacles
Correct answer: Light waves restricted to oscillate in a single plane
Polarization restricts the oscillation of the electric field of light to a single plane perpendicular to the direction of propagation.
Question 5: The frequency of a wave does NOT change when the wave:
- Reflects off a moving mirror
- Passes from one medium to another (Correct answer)
- Is emitted by a moving source
- Is observed by a moving observer
Correct answer: Passes from one medium to another
When a wave passes from one medium to another, its frequency remains constant while its speed and wavelength change.
Question 6: A convex mirror is used as a rearview mirror because it provides:
- A real, magnified image
- A virtual, reduced, wide-angle view (Correct answer)
- A real, reduced image with no distortion
- A virtual, magnified view
Correct answer: A virtual, reduced, wide-angle view
A convex mirror always forms a virtual, upright, and reduced image, giving a wider field of view useful for safety mirrors.
Question 7: The thin lens equation 1/f = 1/do + 1/di uses the sign convention that a virtual image has:
- Positive di
- Negative di (Correct answer)
- di = 0
- di equal to do
Correct answer: Negative di
By the standard sign convention, a virtual image forms on the same side as the incoming light and is assigned a negative image distance.
OAT Physics: Optics and Waves 5
In a single-slit diffraction pattern, the width of the central maximum is affected by: