Which one among the following is the primary reason for asking persons undergoing X-ray imaging to remove metallic objects?
Metallic objects can absorb/reflect X-ray resulting in dark/bright spot
Metallic objects can absorb or reflect X-rays differently from body tissue, which shows up as unwanted dark or bright spots (artifacts) on the resulting X-ray image and can obscure the area being examined. This is the primary reason patients are asked to remove jewellery, belts, and other metallic items before undergoing X-ray imaging.
Which of the following lenses will bend the light rays through the largest angle?
Which one of the following statements is not correct?
A person rings a metallic bell near a strong concrete wall. He hears the echo after 0.3 s. If the sound moves with a speed of 340 m/s, how far is the wall from him?
A sound wave has a frequency of 4 kHz and wavelength 30 cm. How long will it take to travel 2.4 km ?
If the wavelengths corresponding to ultraviolet, visible and infrared radiations are given as λ UV ,λ VIS and λ IR respectively, then which one of the following gives the correct relationship among these wavelengths?
When a light ray enters into glass medium from water at an angle of incidence 0º, what would be the angle of refraction?
The electromagnetic waves, which are used for satellite communication, are
The visible portion of the electromagnetic spectrum is __________.
A person can see near objects clearly through his eyes but cannot see distant objects clearly. The possible reason(s) for this defect could be:
1. Excessive curvature of the eye lens.
2. The eye - ball has become too small.
3. The focal length of the eye lens is too large.
4. Elongation of the eye - ball.
Select the correct answer using the code given below:
Which one of the following statements is correct regarding the travel of a light beam from a rare to a dense medium?
Which of the following is correct?
I. Sound is a mechanical wave
II. Sound wave does not need any medium to propagate
The atmospheric green house effect is produced mainly by the absorption and re-emission of:
Which of the following are examples of electromagnetic waves?
a. Television waves
b. Ultraviolet rays
c. X-rays
d. Sun rays
When light passes from one medium into another medium, then the physical property which does not change is
The ray that comes back from a surface after the reflection is known as ______.