﻿ The angle of incidence at which reflected light totally polarized for reflection from air to glass (refractive index n), is from Physics Class 12 JEE Year 2004 Free Solved Previous Year Papers

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# JEE Physics 2004 Exam Questions

#### Multiple Choice Questions

61.

The binding energy per nucleon of deuteron (21H) and helium nucleus (42He) is 1.1 MeV and 7 MeV respectively. If two deuteron nuclei react to form a single helium nucleus, then the energy released is

• 13.9 MeV

• 26.9 MeV

• 23.6 MeV

• 19.2 MeV

C.

23.6 MeV

As given,
The binding energy per nucleon of a deuteron (1H2 ) = 1.1 MeV
∴ Total binding energy = 2× 1.1 = 2.2 MeV

The binding energy per nucleon of helium (2He4 ) = 7 MeV
∴ Total binding energy = 4× 7 = 28 MeV
Hence, energy released in the above process = 28 - 2× 2.2 = 28 - 4.4 = 23.6 MeV

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62.

According to Einstein’s photoelectric equation, the plot of the kinetic energy of the emitted photo electrons from a metal Vs the frequency, of the incident radiation gives straight line whose slope

• depends on the nature of the metal used

• depends on the intensity of the radiation

• depends both on the intensity of the radiation and the metal used

• is the same for all metals and independent of the intensity of the radiation.

D.

is the same for all metals and independent of the intensity of the radiation.

Einstein's photoelectric equation is
K.E.max = hv − φ ............... (i)

The equation of line is
y = mx + c .............. (ii)

Comparing above two equations m = h, c = - φ

Hence, the slope of the graph is equal to Planck's constant (non-variable) and does not depend on the intensity of radiation.
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63.

Two spherical conductor B and C having equal radii and carrying equal charges in them repel each other with a force F when kept apart at some distance. A third spherical conductor having same radius as that of B but uncharged brought in contact with B, then brought in contact with C and finally removed away from both. The new force of repulsion, between B and C is

• F/4

• 3F/4

• 3F/8

• F/8

C.

3F/8

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64.

The angle of incidence at which reflected light totally polarized for reflection from air to glass (refractive index n), is

• sin−1 (n

• sin−1 (1/n)

• tan−1 (1/n)

• tan−1 (n)

D.

tan−1 (n)

Brewster’s law: According to this law the ordinary light is completely polarised in the plane of incidence when it gets reflected from transparent medium at a particular angle known as the angle of polarisation. n = tan ip.

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65.

An electromagnetic wave of frequency ν = 3.0 MHz passes from vacuum into a dielectric medium with permittivity ε = 4.0. Then

• wavelength is doubled and the frequency remains unchanged

• wavelength is doubled and frequency becomes half

• wavelength is halved and frequency remains unchanged

• wavelength and frequency both remain unchanged.

C.

wavelength is halved and frequency remains unchanged

In vacuum, ε0 = 1
In medium, ε = 4
So, refractive index

Hence, it is clear that wavelength and velocity will become half but frequency remains unchanged when the wave is passing through any medium.

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66.

An α-particle of energy 5 MeV is scattered through 180° by a fixed uranium nucleus. The distance of the closest approach is of the order of

• 1 Å

• 10−10 cm

• 10−12 cm

• 10−15 cm

C.

10−12 cm

At closest approach, all the kinetic energy of the α-particle will converted into the potential energy of the system, K.E. = P.E.

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67.

A nucleus disintegrates into two nuclear parts which have their velocities in the ratio 2:1. The ratio of their nuclear sizes will be

• 21/3:1

• 1:31/2

• 31/2:1

• 1:21/3

B.

1:31/2

Law of conservation of momentum gives
m1 v1 = m2 v2

222 Views

68.

The work function of a substance is 4.0 eV. Then longest wavelength of light that can cause photoelectron emission from this substance approximately

• 540 nm

• 400 nm

• 310 nm,

• 220 nm

C.

310 nm,

350 Views

69.

The thermistors are usually made of

• metals with low temperature coefficient of resistivity

• metals with high temperature coefficient of resistivity

• metal oxides with high temperature coefficient of resistivity ‘

• semiconducting materials having low temperature coefficient of resistivity.

C.

metal oxides with high temperature coefficient of resistivity ‘

These are devices whose resistance varies quite markedly with temperature mean having high-temperature coefficient of resistivity. [Their name are derived from thermal resistors]. Depending on their composition they can have either negative temperature coefficient or positive temperature coefficient or positive temperature coefficient or positive temperature coefficient characteristics. The negative temperature coefficient types consist of a mixture of oxides of iron, nickel and cobalt with small amounts of other substance. The positive temperature coefficient types are based on barium titanate.

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70.

The maximum number of possible interference maxima for slit-separation equal to twice the wavelength in Young’s double-slit experiment is

• infinite

• five

• three

• zero

B.

five

For interference maxima, d sin θ = nλ Here d = 2λ
∴ sin θ = n/2 and is satisfied by 5 integral values of n (−2, −1, 0, 1, 2), as the maximum value of sin θ can only be 1.

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