Wave motion

41. Television viewer using dish antenna to receive satellite signal do not receive signals during rain because : [U.P.P.C.S.(pre) 2017]

1. of small size of antenna.
2. rain droplets absorb the energy of the radio waves.
3. rain droplets disperse the energy of radio waves from their original direction.
which of the above statement are correct ?

(a) only 1
(b) only 1 and 2
(c) only 2 and 3
(d) 1,2 and 3

Correct Answer: (d) 1,2 and 3

Solution:During rain, radio waves collide with raindrops partly/completely and converted into thermal energy absorbing the energy of radio waves. Rain drops are also capable of disturbing the basic direction of energy of the radio waves.

Due to this reason, there is difficulty in receiving satellite signals during rain. Radio signals become weak during rain. which can not be received by small antenna.

42. Following rays are used in the diagnosis of the intestinal diseases : [43rd B.P.S.C. (PRE) 1999]

(a) x-rays
(b) α-rays
(c) β-rays
(d) γ-rays

Correct Answer: (a) x-rays

Solution:X-rays are a form of electromagnetic radiations which are used in the diagnosis of intestinal diseases.

43. CT scan done by using- [U.P.P.C.S.(MAINS) 2011]

(a) infrared rays.
(b) ultrasonic wave.
(c) visible light.
(d) x-rays.

Correct Answer: (d) x-rays.

Solution:CT scan or computed tomography are special x-rays tests that produce cross-sectional images of the body using x-rays and a computer.

44. Which of the following was invented by Wilhelm Rontgen? [U.P.P.C.S.(pre) 2018]

(a) radio
(b) x-ray machine
(c) electric bulb
(d) none of the above.

Correct Answer: (b) x-ray machine

Solution:X-ray a type of electromagnetic wave was discovered by the Wilhelm Rontgen, with wavelength in the range of 0.01 to 10 nanometres. These rays are the extensively used in the field of medical and industries.