- AMetals
- BSuper conductors
- CInsulators
- DSemiconductors
Explanation:
In insulators, the electrons are tightly bound with the nucleus hence, at room temperature thermal energy is not enough to push the electrons into conduction band and hence, no electrons are available for conduction.
The energy required for electron to escape out from orbit and to over come the energy gap is thus of the order of 6 eV, while for semiconductors and conductors it is (of the order of) 1 eV and 0 respectively.
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Focal length of a convex lens of refractive index 1.5 is 2 cm. Focal length of lens when immersed in a liquid of refractive index of 1.25 will be
|
(a) 10 cm |
(b) 2.5 cm |
(c) 5 cm |
(d) 7.5 cm |
The imaginary line passing through the pole and the center of curvature of the curved mirror is called its _______.
The magnetic moment of a current (i) carrying circular coil of radius (r) and number of turns (n) varies as
|
(a) 1/ r2 |
(b) 1/ r |
(c) r |
(d) r2 |
In Young’s double slit experiment the wavelength of light was changed from 7000 Å to 3500 Å. While doubling the separation between the slits which of the following is not true for this experiment
|
(a) The width of the fringes changes |
|
(b) The colour of bright fringes changes |
|
(c) The separation between successive bright fringes changes |
|
(d) The separation between successive dark fringes remains unchanged |
The cut-in voltage for silicon diode is approximately
| (a) 0.2 V | (b) 0.6 V | (c) 1.1 V | (d) 1.4 V |

A wire 100 cm long and 2.0 mm diameter has a resistance of 0.7 ohm, the electrical resistivity of the material is
|
(a) 4.4 |
(b) 2.2 |
|
(c) 1.1 |
(d) 0.22 |
