NEET Physics Electromagnetic Spectrum MCQs

a) Visible light

b) Microwaves

c) uv-rays

d) Radio waves

Answer: Visible light

Question: The range of wavelength of visible light is

a) 4000 Å to 8000 Å

b) 15,000 Å to 25,000 Å

c) 50 Å to 500 Å

d) 9000 Å to 25,000 Å

Answer: 4000 Å to 8000 Å

Question: Which of the following is the infrared wavelength?

a) 10^–4 cm

b) 10^–6 cm

c) 10^–5 cm

d) 10^–7 cm

Answer: 10^–4 cm

Question: The wavelength of X-ray is of the order of

a) 1 angstrom

b) 1 cm

c) 1 micron

d) 1 metre

Answer: 1 angstrom

Question: Radio waves do not penetrate in the band of

a) ionosphere

b) mesosphere

c) troposphere

d) stratosphere

Answer: ionosphere

Question: What is the cause of “Green house effect”?

a) Infrared rays

b) Ultraviolet rays

c) Radio waves

d) X-rays

Answer: Infrared rays

Question: The waves which are electromagnetic in nature are

a) light waves and X-rays

b) sound waves and water waves

c) water waves and radio waves

d) sound waves and light waves

Answer: light waves and X-rays

Question:Assertion : The basic difference between various types of electromagnetic waves lies in their wavelength or frequencies.
Reason : Electromagnetic waves travel through vacuum with the same speed

a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.

b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion

c) Assertion is correct, reason is incorrect

d) Assertion is incorrect, reason is correct.

Answer: Assertion is correct, reason is correct; reason is a correct explanation for assertion.

Question: The ozone layer in the atmosphere absorbs

a) X-rays and ultraviolet rays

b) only the radiowaves

c) only the visible light

d) None of these

Answer: X-rays and ultraviolet rays

Question: Which one of the following has the maximum energy?

a) Ultraviolet rays

b) Radio waves

c) Infrared rays

d) Micro waves

Answer: Ultraviolet rays

Question:  Which one of the following has the shortest wavelength?

a) Gamma rays

b) Ultraviolet rays

c) Infrared rays

d) Microwaves

Answer: Gamma rays

Question: The velocity of all radio waves in free space is 3 × 10⁸ m/s. The frequency of a radio wave of wavelength 150m is

a) 2 MHz

b) 1 MHz

c) 2 kHz

d) 20 kHz

Answer: 2 MHz

Question: Microwaves are electromagnetic waves with frequency in the range of

a) Giga hertz

b) Hertz

c) Micro hertz

d) Mega hertz

Answer:  Giga hertz

Question: Ozone layer above earth’s atmosphere will not

a) reflect back radio waves

b) prevent ultraviolet rays from sun

c) prevent infra red radiations originated from earth from escaping earth’s atmosphere

d) prevent infrared radiations from sun reaching earth

Answer: reflect back radio waves

Question: The frequency of electromagnetic wave, which best suited to observe a particle of radii 3 × 10^–4 cm is of the order of

a) 10¹⁵

b) 10¹⁴

c) 10¹³

d) 10¹²

Answer: 10¹⁵

Spectrum

Dispersion and Recombination of White Light
The angle between the two refracting faces of a prism is called the angle of the prism or refracting angle ‘A’.
The angle between the incident ray and the emergent ray is called the angle of the deviation‘d’.
The angle of deviation depends on:
• The angle of incidence for A given colours is called dispersion.
• The angle of the prism
• The colour of the light incident on the prism
• The material of the prism
The splitting of white light into its constituent’s colours is called dispersion.
When white light passes through a prism, a band of seven colours obtained, which is called the spectrum.
A rainbow is a natural spectrum that occurs in the sky.

Human Eye and Colourful World- Dispersion and scattering of Light
A prism is a piece of glass or any other transparent material, having two triangular and three rectangular faces.
A light ray refract twice as it propagates through a prism.
• Refracting surface are the rectangular faces of triangular prism.
• The refracting edge is the line along which the two refracting surface meet.
• The angle of a prism is the angle between the two refracting faces. It is denoted by capital letter A.
• The base of the prism is one of the rectangular faces of prism that does not take part in refraction.
• The incident ray is the ray of light that is incident on a refracting surface.
• Thee refracted ray is the ray that deviates at the point of incidence and travel inside the prism between two refracting surfaces.
• The emergent ray is the light ray emerging from the prism after refraction.
• Angle of incidence is the angle formed between the refracted ray and the normal at the point of incidence.
• Angle of refraction is the angle between the normal and the refracted ray at the point of incidence.
• Angle of deviation is the angel between the incident ray. It is represented Greek letter δ or θ_d or D.
Dispersion is the splitting of light into its constituents, revealing different colours depending on the wavelengths.
Atmospheric refraction is the apparent random wavering or flickering of object seen due to inconsistency in the physical conditions of the refracting medium such as air.
Scattering is the deviation of light rays from its straight path.
Tyndall effect is the scattering of a light beam by colloidal particles, illuminating the path of the beam.
The Tyndall beam is the illuminated path of a light beam in a colloidal solution.

Electromagnetic Spectrum
Electromagnetic waves just beyond the red region of the visible spectrum are called infrared radiations.
Electromagnetic waves just beyond the violet region of the spectrum are called ultraviolet radiations.
Electromagnetic waves consist of oscillating electric and magnetic fields, which are mutually perpendicular to each other and also perpendicular to the direction of propagation of the wave.
Gamma radiations are used in medicine for cancer treatment and also in industries to check welding.
X-rays are used as a diagnostic tool.
UV rays are being used in a variety of applications such as Lasik eye surgery, water purifiers and fake note detectors.
Infrared rays are used to track diseases on crop by remote sensing.
Infrared rays are used in photography at night, and also in mist fog, as they are not scattered much because of their very long wavelengths.
Microwaves are used in microwave ovens to cook or heat food or liquids.
Microwaves are also used in the field of communication.
Radio waves are used in radar communication, in radio and television communication and in cellular phone communication networks