- APerpendicular to the field.
- BFrom stronger to the weaker parts of the field.
- CFrom weaker to the stronger parts of the field.
- DNone of these.
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Two long parallel wires are at a distance 2d apart. They carry steady equal currents flowing out of the plane of the paper, as shown. The variation of the magnetic field B along the line XX’ is given by
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(a)
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(b)
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(c)
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(d)
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A short-circuited coil is placed in a time-varying magnetic field. Electrical power is dissipated due to the current induced in the coil. If the number of turns were to be quadrupled and the wire radius halved, the electrical power dissipated would be
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(a) Halved |
(b) The same |
(c) Doubled |
(d) Quadrupled |
Assertion : The electromagnetic waves of shorter wavelength can travel longer distances on earth's surface than those of longer wavelengths.
Reason : Shorter the wavelength, the larger is the velocity of wave propagation.
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(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
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(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
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(c) If assertion is true but reason is false. |
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(d) If the assertion and reason both are false. |
A lens which has focal length of 4 cm and refractive index of 1.4 is immersed in a liquid of refractive index 1.6, then the focal length will be
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(a) – 12.8 cm |
(b) 32 cm |
(c) 12.8 cm |
(d) – 32 cm |
A battery of internal resistance 4W is connected to the network of resistances as shown. In order to give the maximum power to the network, the value of R (in Ω) should be
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(a) 4/9 |
(b) 8/9 |
(c) 2 |
(d) 18 |
Assertion : Radioactivity of
undecayed radioactive nuclei of half life of 50 days is equal to that of 1.2
number of undecayed nuclei of some other material with half life of 60 days
Reason : Radioactivity is proportional to half-life.
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(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
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(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
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(c) If assertion is true but reason is false. |
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(d) If the assertion and reason both are false. |
An important spectral emission line has a wavelength of 21 cm. The corresponding photon energy is (h = 6.62 ![]()
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(a) 5.9 |
(b) 5.9 |
(c) 5.9 |
(d) 11.8 |