- AZero potential.
- BVery low potential.
- CNegative potential.
- DHigh potential.
Explanation:
When voltage is applied to an electrolyte, dissociation of ions starts.
At low voltages as the voltage increases the number of ions conducting also increases making a non linear increase of current.
After a certain voltage when the ions are dissociated and no more dissociation, the electrolyte behaves as a conductor and obeys ohm's law.
Thus at high voltages, an electrolyte obeys ohm's law.
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Assertion : Television signals are received through sky-wave propagation.
Reason : The ionosphere reflects electromagnetic waves of frequencies greater than a certain critical frequency.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
The distance of two points on the axis of a magnet from its centre is 10 cm and 20 cm respectively. The ratio of magnetic intensity at these points is 12.5 : 1. The length of the magnet will be
| (a) 5 cm | (b) 25 cm | (c) 10 cm | (d) 20 cm |
A convex lens forms a real image of a point object placed on its principal axis. If the upper half of the lens is painted black, the image will
|
(a) Be shifted downwards |
(b) Be shifted upwards |
|
(c) Not be shifted |
(d) Shift on the principal axis |
Assertion : The electrical conductivity of earth's atmosphere decreases with altitude.
Reason : The high energy particles (i.e. 𝛾-rays and cosmic rays) coming from outer space and entering our earth's atmosphere cause ionisation of the atoms of the gases present there and the pressure of gases decreases with increase in altitude.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If assertion is false but reason is true. |
Energy required to remove an electron from aluminium surface is 4.2 eV. If light of wavelength 2000 Å falls on the surface, the velocity of the fastest electron ejected from the surface will be
|
(a) 8.4 |
(b) 7.4 |
(c) 6.4 |
(d) 8.4 |
When a compact disc is illuminated by a source of white light. Coloured 'lanes' are observed. This is due to
|
(a) Dispersion |
(b) Diffraction |
(c) Interference |
(d) Refraction |
Which of one is correct
|
(a) |
(b) |
(c) |
(d) |