Physics Test 9 - Electromagnetic Waves, Optics, Modern Physics | 25 Questions MCQ Test Mock Test Series for JEE Main & Advanced 2022 JEE

QUESTION: 1

A red LED emits light at 0.1 watt uniformly around it. The amplitude of the electric field of the light at a distance of 1 m from the diode is

A.
1.73 V/m
B.
2.45 V/m
C.
5.48 V/m
D.
7.75 V/m

Solution:

QUESTION: 2

The resolution limit of the eye is 1 minute. At a distance of X km from the eye, two persons stand with a lateral separation of 3 meters. For the two persons to be just resolved by the naked eye, X should be

A. 10 km
B. 15 km
C. 20 km
D. 30 km

Solution:

QUESTION: 3

In Young's double slit experiment, the fringe width is found to be 0.4 mm. If the whole apparatus is immersed in water of refractive index 4/3 without disturbing the geometrical arrangement, the new fringe width will be

A. 0.30 mm
B. 0.40 mm
C. 0.53 mm
D. 0.50 mm

Solution:

QUESTION: 4

For a prism of refractive index

the angle of the prism

is equal to the angle of minimum deviation.The value of

A.
B.
C.
D.

Solution:

QUESTION: 5

Two optical media of refractive indices n1 and n2 contain x and y waves of the same colour in the same thickness. Then their relative refractive index

is equal to

A. x-y
B. y/x
C. (y-x)/x
D. x /(y-x)

Solution:

QUESTION: 6

The focal length of a convex lens is 10 cm and its

is 1.5. If the radius of curvature of one surface is 7.5 cm,the radius of curvature of the second surface will be

A. 7.5 cm
B. 15.0 cm
C. 75 cm
D. 5.0 cm

Solution:

QUESTION: 7

The refractive index of violet and red light are 1.54 and1.52 respectively. If the angle of prism is

the angular dispersion is

A.
B.
C.
D.

Solution:

QUESTION: 8

Interference fringes are obtained using two coherent sources whose intensities are in ratio 4 : 1. Then the ratio of the intensities of the bright and dark bands is

A. 4 : 1
B. 5 : 1
C. 9 : 1
D. 25 : 9

Solution:

QUESTION: 9

A ray of light passes through an equilateral prism such that the angle of incidence is equal to the angle of emergence and the latter equal to (3/4)th the angle of
the prism. The angle of deviation will be

A.
B.
C.
D.

Solution:

QUESTION: 10

A point object is placed at a distance of 10cm & its real image is formed at a distance of 20 cm from a concave mirror. If the object is moved by 0.1 cm towards the mirror, the image will shift by

A. 0.4 cm away from the mirror
B. 0.8 cm away from the mirror
C. 0.4 cm towards the mirror
D. 0.8 cm towards the mirror

Solution:

QUESTION: 11

Angle of a prism is A and its one surface is slivered.Light rays falling at an angle of incidence 2 A on first surface returns back, through, the same path after
suffering reflection at the second silvered surface.Refractive index of material is

A. 2 sin A
B. 2 cos A
C. (1/2) cos A
D. tan A

Solution:

QUESTION: 12

Diamond shines due to its

A. low refractive index
B. high refractive index
C. high critical angle
D. none of these

Solution:

QUESTION: 13

When a beam of accelerated electrons hit a target a continuous X-ray spectrum is emitted from the target.Which one of these wavelengths is absent in the X-ray
spectrum if the X-rays tube is operated at 40,000V ?

A. 0.25 Å
B. 0.5 Å
C. 1.0 Å
D. 1.5 Å

Solution:

QUESTION: 14

The radio transmitter operates on a wavelength of 1500m at a power of 400 kilowatt. The energy of radiophoton in Joules is

A.
B.
C.
D.

Solution:

QUESTION: 15

What are the essential properties a medium must possess for the propagation of mechanical waves?

A.
Stable pressure
B.
Maximum friction
C.
Constant temperature
D.
Minimum friction

Solution:

The friction force amongst the particles of the medium should be negligibly small so that they continue oscillating for a sufficiently long time and the wave travels a sufficiently long distance through the medium

QUESTION: 16

The wavelength of the first line of Balmer series of hydrogen atom is l Å. The wavelength of this line of a double ionised lithium atom Z = 3) is

A. l/3
B. l/9
C. l/8
D. l/27

Solution:

QUESTION: 17

A freshly prepared radioactive source of half life 2 hrs emits radiations of intensity which is 64 times the permissible safe level. The minimum time after which it would be possible to work safely with this source is

A. 6 hrs
B. 12 hrs
C. 24 hrs
D. 128 hrs

Solution:

QUESTION: 18

A gamma ray photon creates an electron positron pair. If the rest mass energy of an electron is 0.5MeV and the total kinetic energy of the electron positron pair is 0.5 MeV, then the energy of the gamma ray photon must be

A. 1 MeV
B. 1.5 MeV
C. 2.0 MeV
D. 0.5 MeV

Solution:

QUESTION: 19

In the thermonuclear reaction

the energy
released per nucleon of the reactants is

A. 21.6 MeV
B. 7.2 MeV
C. 3.6 MeV
D. 10.8 MeV

Solution:

QUESTION: 20

The relationship between α and β is given by

A.
α = β
B.
α =1/ β
C.
β = α/(1-α)
D.
β = α/(1+α)

Solution: