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Magnetic field of a short magnet at a distance lm on axial line is 1 oersted at a distance 2 m on the same line the intensity in oersted is
0.75
0.125
0.25
0.5
B.
0.125
The distance between the poles of horse shoe magnet is 10 cm and its pole strength is 104 A. The magnetic field induction at point P mid-way between the poles is
4×10-19 tesla
2×10-9 tesla
zero
A.
The magnetic needle of a tangent galvanometer is deflected at an angle 30° due to a magnet. The horizontal component of earth's magnetic field 0.34 x 10-4 T is along the plane of the coil. The magnetic intensity is
1.96 × 10-4 T
1.96 × 104 T
1.96 × 10-5 T
1.96 × 105 T
C.
1.96 × 10-5 T
Angle through which magnet is deflected (θ) = 30°
and horizontal magnetic field (BH) = 0.34 × 10-4 T
Magnetic intensity = BH tanθ
= 034 × 10-4 × tan30°
= (0.34 × 10-4 ) × 0.577
Magnetic intensity = 1.96 × 10-5 T
At a certain place, magnitude of horizontal and vertical components of a magnetic field are same. The total intensity of magnetic field at that place will be
H
H2
2H
D.
Given:
H = V ...(i)
where, H = horizontal component of magnetic field
V = vertical component of magnetic fireld
Resultant intensity
I =
I =
I =
I = H
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Function: _error_handler
File: /var/www/html/public_html/application/views/competition/entrance_exam_questions.php
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File: /var/www/html/public_html/application/controllers/Study.php
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File: /var/www/html/public_html/index.php
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Function: require_once
Assertion: A famous painting was painted by not using brush strokes in the usual manner, but rather a myriad of small color dots. In this painting the color you see at any given place on the painting changes as you move away.
Reason: The angular seperation of adjacent dots changes with the distance from the painting.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
A.
If both assertion and reason are true and reason is the correct explanation of assertion
Since superconductors exist below a certain critical temperature and above that temperature they behave like normal materials. When magnet is placed above superconductor and cooled using liquid nitrogen. The induced magnetic field inside the superconductor is exactly equal and opposite in direction to the applied magnetic field, so that they cancel within the superconductor. These poles will repel each other and the force of repulsion is enough to float the magnet.
Assertion: Faraday's laws are consequences of conservation of energy.
Reason: In a purely resistive A.C. circuit, the current lags behind the e.m.f. in phase.
If both the assertion and reason are true and reason is a correct explanation of the assertion.
If both assertion and reason are true but assertion is not a correct explanation of the assertion.
If the assertion is true but the reason is false.
If both assertion and reason are false.
C.
If the assertion is true but the reason is false.
Faraday's laws involve conservation of mechanical energy into electrical energy. This is in accordance with the law of conservation of energy. We also know that in pure resistance, the e.m.f. is in phase with the current.
The ratio of magnetic moments of two short magnets which give null deflection in tan B position at 12 cm and 18 cm from the centre of a deflection magnetometer is
4:9
27:8
2:3
8:27
D.
8:27
Liquid oxygen remains suspended between two pole faces of a magnet because it is
diamagnetic
paramagnetic
ferromagnetic
antiferromagnetic
B.
paramagnetic
MolecLiquid oxygen has extra electrons, which do not form complete pairs of opposite spin. Liquid oxygen has a light blue colour and is highly paramagnetic. The atomic magnetic dipoles align with an external magnetic field. This effect occurs due to quantum mechanical spin as well as electron orbital angular momentum. When suspended between two pole faces of a magnet it acquires feeble magnetism hence remains suspended. Note:- Paramagnetism requires that the atoms individually have permanent dipole moment even without an applied field, which typically implies a partially filled electron shell.
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File: /var/www/html/public_html/application/views/competition/entrance_exam_questions.php
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A frog can be levitated in a magnetic field produced by a current in a vertical solenoid placed below the frog. This is possible because the body of the frog behaves as
paramagnetic
diamagnetic
ferromagnetic
antiferromagnetic
A.
paramagnetic
n the presence of an external magnetic field, the atomic dipoles of paramagnetic substances are aligned along the field. The material gets magnetized and it produces an extra magnetic field in the material in the direction of the field. So for paramagnetic materials, the resultant field is greater than the applied field. As the body of a frog behaves like a paramagnetic substance, the smallest magnetic field on the body of the frog will be strong enough to lift it up.
Velocity of light is equal to
εo/ μo
D.
Relation for velocity of light (c) =
where εo = permittivity constant equal to 8.85 × 10-12 F/m
μo = permeability constant equal to 1.26 × 10-6 H/m
Numerical velocity of light
( c ) =
=
(c) ≈ 3 × 108 m/s
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File: /var/www/html/public_html/application/views/competition/entrance_exam_questions.php
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Function: view
File: /var/www/html/public_html/application/controllers/Study.php
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Function: view
File: /var/www/html/public_html/index.php
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Function: require_once