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The correct ANSWER is (d) INFRARED waves

Explanation: Infrared waves can be used to take PHOTOGRAPHS during conditions of smoke, FOG, etc. as these waves are scattered LESS than visible rays and hence travel longer distances through the atmosphere. So, using infrared waves can help Monica out.

The CORRECT answer is (b) Ultra-high frequency

Easy explanation: UHF stands for Ultra high frequency. Cellular phones USED radio waves to transmit voice communication in the Ultra high-frequency Band. The UHF band extends from 900 MHZ to 5 x 109 Hz or 5000 MHz. Radio waves are produced by oscillating circuits having an INDUCTOR and capacitor.

Correct choice is (b) Vm = VI = Vu

To explain: The correct combination is ➔Vm = Vi = Vu. This is because, in vacuum, all the electromagnetic waves in question will travel at the same speed. The speed with which they travel in vacuum is the speed of LIGHT. (C = 3 × 10^8 m/s).

The correct CHOICE is (b) Ultraviolet RAYS

The explanation: Ultraviolet (UV) radiations in large quantities are highly harmful to humans. These rays in solar radiation on REACHING earth are absorbed by the ozone layer in the atmosphere. UV rays are produced by SPECIAL lamps such as mercury and from arc lamps and by very hot bodies like the sun.

Correct answer is (c) 1

For explanation: RATIO = 1 because the speed of an electromagnetic WAVE in vacuum is independent of its wavelength or FREQUENCY. Therefore, the ratio of speed of infrared and ULTRAVIOLET rays in a vacuum is one.

Correct choice is (b) Emicro < Einfrared < Evisible < Eultraviolet < Egamma

The best I can explain: The energy of electromagnetic waves is DIRECTLY proportional to the frequency of the electromagnetic waves. So the order of frequency is GIVEN as:

vmicro < vinfrared < vvisible < vultraviolet < vgamma

Since E=hv ➔ E ∝ v

The order of energy is as FOLLOWS:

Emicro < Einfrared < Evisible < Eultraviolet < Egamma

The CORRECT choice is (a) True

The best explanation: Yes, microwaves are produced by special vacuum TUBES such as klystrons and MAGNETRONS. Microwaves are high-frequency radio WAVES of frequency range 1 G Hz to 300 G Hz. Microwaves are used in radar SYSTEMS and the study of atomic and molecular structure.

The correct choice is (c) Radio Waves

For EXPLANATION I WOULD say: Radio Waves are generally in the frequency range ➔ 500 kHz to 1000 MHz. Radio waves are used for long-distance communication, such as in TELEVISION, mobiles, and radios. These devices receive radio waves and CONVERT them to mechanical vibrations in the speaker to create sound waves.

The CORRECT answer is (C) 3 × 10^18 to 5 × 10^22 Hz

To EXPLAIN: The FREQUENCY range of Gamma rays is 3 × 10^18 to 5 × 10^22 Hz. These rays have a wavelength of 6 × 10^-13 to 10^-10m. Gamma rays are PRODUCED in nuclear reactions and are also emitted by radioactive nuclei.

Right option is (d) More than 1

The explanation is: The RATIO of frequencies of UV rays and IR rays in the glass is more than 1.This is because the frequency of UV rays is greater than that of infrared rays. This situation is applicable in glass or vacuum or AIR.

Correct choice is (b) False

The best I can explain: No, the suggestion is not going to help STEPHEN. Even though X-rays have higher energy than light waves and can pass through the BODY, it is not of great VALUE in the early diagnosis of pathological conditions of bones and joints like tuberculosis. This is because, in the early stages of the disease, the damage to the lungs may not yet have BECOME sufficiently marked in the X-ray to be detectable, so people who have active tuberculosis can be missed.

Right OPTION is (a) Electromagnetic SPECTRUM

To EXPLAIN: The classification of electromagnetic waves done according to the frequency called the electromagnetic spectrum. The basic difference various type of electromagnetic waves lies in their wavelength or frequency since all of them travel through vacuum at the same speed and also, the waves differ in their mode of INTERACTION with matter.

The correct ANSWER is (c) 20 m to 120 m

Easy explanation: Maximum wavelength in the band will correspond to the LOWEST frequency:

c=fminλmax

λmax=\(\frac {c}{f_{min}}=\frac {3\times 10^8}{2.5\times 10^6}\)=120 m

Minimum wavelength in the band will correspond to the HIGHEST frequency:

c=fmaxλmin

λmin=\(\frac {c}{f_{max}} =\frac {3\times 10^8}{15 \times 10^6 }\)=20 m

Therefore, the CORRESPONDING wavelength band is 20 m to 120 m.

The CORRECT answer is (b) 1.85 × 10^-15 s

Explanation: T = \(\frac {1}{V}\)

T = \(\frac {\LAMBDA }{c}\)

T = 5550 × \(\frac {10^{-10}}{3}\) × 10^8

T = 1.85 × 10^-15 s.