# +2 Physics - Unit 5 - Electromagnetic Waves And Wave Optics

14 Questions  Settings  Prepared by P. ILAIYARAJA M. Sc. ,B. Ed. , PG ASST IN PHYSICS , GHSS, PANCHANATHIKKULAM EAST, NAGAI DT.   ; & www. Padasalai. Net

Questions and Answers
• 1.
In an electromagnetic wave
• A.

Power is transmitted in a direction perpendicular to both the fields

• B.

Power is transmitted along electric field

• C.

Power is transmitted along magnetic field

• D.

power is equally transferred along the electric and magnetic fields

• 2.
Electromagnetic waves are
• A.

Transverse

• B.

Longitudinal

• C.

May be longitudinal or transverse

• D.

Neither longitudinal nor transverse

• 3.
Refractive index of glass is 1.5. Time taken for light to pass through a glass plate of thickness 10 cm is
• A.

(4)

• B.

(3)

• C.

(2)

• D.

(1)

• 4.
In an electromagnetic wave the phase difference between electric field and magnetic field is
• A.

Zero

• B.

π/2

• C.

π/4

• D.

π

• 5.
Atomic spectrum should be
• A.

Pure line spectrum

• B.

Absorption line spectrum

• C.

Absorption band spectrum.

• D.

Emission band spectrum

• 6.
When a drop of water is introduced between the glass plate and plano convex lens in Newton’s rings system, the ring system
• A.

Contracts

• B.

Expands

• C.

First expands, then contracts

• D.

Remains same

• 7.
A beam of monochromatic light enters from vacuum into a medium of refractive index μ. The ratio of the wavelengths of the incident and refracted waves is
• A.

(1)

• B.

(2)

• C.

(3)

• D.

(4)

• 8.
If the wavelength of the light is reduced to one fourth, then the amount of scattering is
• A.

Increased by 256 times

• B.

Decreased by 256 times decreased by 256 times

• C.

increased by 16 times

• D.

Decreased by 16 times

• 9.
In Newton’s ring experiment the radii of the m th and (m + 4) th dark rings are respectively and . What is the value of m?
• A.

10

• B.

8

• C.

4

• D.

2

• 10.
The path difference between two monochromatic light waves of wavelength 4000 Å is  m. The phase difference between them is
• A.

π

• B.

• C.

3π/2

• D.

π/2

• 11.
In Young’s experiment, the third bright band for wavelength of light 6000 Å coincides with the fourth bright band for another source in the same arrangement. The wave length of the another source is
• A.

4500 Å

• B.

6000 Å

• C.

5000 Å

• D.

4000 Å

• 12.
A light of wavelength 6000 Å is incident normally on a grating 0.005 m wide with 2500 lines. Then the maximum order is
• A.

3

• B.

2

• C.

1

• D.

4

• 13.
A diffraction pattern is obtained using a beam of red light. What happens if the red light is replaced by blue light?
• A.

Diffraction pattern becomes narrower and crowded together

• B.

Bands disappear

• C.

no change

• D.

Diffraction pattern becomes broader and farther apart

• 14.
The refractive index of the medium, for the polarising angle
• A.

1.732

• B.

1.414

• C.

1.5

• D.

1.468

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