A circular loop carrying a current is replaced by an equivalent magnetic dipole. A point on the axis of the loop is
|
(a) An end-on position |
(b) A broad side-on position |
|
(c) Both (a) and (b) |
(d) Neither (a) nor (b) |
(a) An end-on position
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Which of the following is incorrect statement regarding photon
|
(a) Photon exerts no pressure |
(b) Photon energy is hv |
|
(c) Photon rest mass is zero |
(d) None of these |
A capacitor is charged by using a battery which is then disconnected. A dielectric slab is then slipped between the plates, which results in
|
(a) Reduction of charge on the plates and increase of potential difference across the plates |
|
(b) Increase in the potential difference across the plate, reduction in stored energy, but no change in the charge on the plates |
|
(c) Decrease in the potential difference across the plates, reduction in the stored energy, but no change in the charge on the plates |
|
(d) None of the above |
In producing X-rays a beam of electrons accelerated by a potential difference V is made to strike a metal target. For what value of V, X-rays will have the lowest wavelength of 0.3094 Å
| (a) 10 kV | (b) 20 kV | (c) 30 kV | (d) 40 kV |
If rotational velocity of a dynamo armature is doubled, then induced e.m.f. will become
|
(a) Half |
(b) Two times |
(c) Four times |
(d) Unchanged |
The third line of Balmer series of an ion equivalent to hydrogen atom has wavelength of 108.5 nm. The ground state energy of an electron of this ion will be
|
(a) 3.4 eV |
(b) 13.6 eV |
(c) 54.4 eV |
(d) 122.4 eV |
A laser beam of pulse power 1012 watt is focussed on an object are 10–4 cm2. The energy flux in watt/ cm2 at the point of focus is
|
(a) 1020 |
(b) 1016 |
(c) 108 |
(d) 104 |