- A30K
- B40K
- C50K
- D60K
Explanation:
Bell laboratory has developed superconductor at a temperature of 40 K.Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic flux fields occurring in certain materials, called superconductors, when cooled below a characteristic critical temperature. It was discovered by Dutch physicist Heike Kamerlingh Onnes on April 8, 1911, in Leiden.
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The energy of a hydrogen atom in its ground state is -13.6eV. The energy of the level corresponding to the quantum number n = 2 (first excited state) in the hydrogen atom is
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(a) – 2.72 eV |
(b) – 0.85 eV |
(c) – 0.54 eV |
(d) – 3.4 eV |
Assertion : No interference pattern is detected when two coherent sources are infinitely close to each other.
Reason : The fringe width is inversely proportional to the distance between the two slits.
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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 long wire A carries a current of 10 amp. Another long wire B, Which is parallel to A and separated by 0.1m from A, carries a current of 5 amp, in the opposite direction to that in A. what is the magnitude and nature of the force experienced per unit length of B (![]()
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(a) Repulsive force of |
(b) Attractive force of |
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(c) Repulsive force of 2π × |
(d) Attractive force of 2π |
In a certain double slit experimental arrangement interference fringes of width 1.0 mm each are observed when light of wavelength 5000 Å is used. Keeping the set up unaltered, if the source is replaced by another source of wavelength 6000 Å, the fringe width will be
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(a) 0.5 mm |
(b) 1.0 mm |
(c) 1.2 mm |
(d) 1.5 mm |
Two electric bulbs (60W and 100W respectively) are connected in series. The current passing through them is
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(a) More in 100W bulb |
(b) More in 60W bulb |
(c) Same in both |
(d) None of these |
Energy stored in electromagnetic oscillations is in the form of
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(a) Electrical energy |
(b) Magnetic energy |
(c) Both (a) and (b) |
(d) None of these |