Consider the following two statements:
- Line spectra contain information about atoms.
- Band spectra contain information about molecules.
- ABoth A and B are wrong
- BA is correct but B is wrong.
- CB is correct but A is wrong
- DBoth A and B are correct.
Consider the following two statements:
Explanation:
Because line spectra contain wavelengths that are absorbed by atoms and band spectra contain bunch wavelengths that are absorbed by molecules, both statements are correct.
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A ray of light passes through four transparent media with refractive indices and
as shown in the figure. The surfaces of all media are parallel. If the emergent ray CD is parallel to the incident ray AB, we must have
|
(a) |
(b) |
(c) |
(d) |
With a change of load resistance of a triode, used as an amplifier, from 50 kilo ohms to 100 kilo ohms, its voltage amplification changes from 25 to 30. Plate resistance of the triode is
|
(a) 25 kW |
(b) 75 kW |
(c) 7.5 kW |
(d) 2.5 kW |
Television signals on earth cannot be received at distances greater than 100 km from the transmission station. The reason behind this is that
|
(a) The receiver antenna is unable to detect the signal at a distance greater than 100 km |
|
(b) The TV programme consists of both audio and video signals |
|
(c) The TV signals are less powerful than radio signals |
|
(d) The surface of earth is curved like a sphere |
The grid voltage of any triode valve is changed from –1 volt to – 3 volt and the mutual conductance is 3 mho. The change in plate circuit current will be
|
(a) 0.8 mA |
(b) 0.6 mA |
(c) 0.4 mA |
(d) 1 mA |

When the current i is flowing through a conductor, the drift velocity is v. If 2i current is flowed through the same metal but having double the area of cross-section, then the drift velocity will be
|
(a) v/4 |
(b) v/2 |
(c) v |
(d) 4v |