- Phosphorus.
- Boron.
- Antimony.
- Aluminium.
Boron.
Aluminium.
Explanation:
A p-type semiconductor is formed by doping an intrinsic semiconductor with a trivalent atom (atom having valency 3). As phosphorous and boron have three valence electrons, they can be doped with silicon to make a p-type semiconductor.
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What is the current (i) in the circuit as shown in figure
|
(a) 2 A |
(b) 1.2 A |
(c) 1 A |
(d) 0.5 A |
A plane wavefront (λ = 6 falls on a slit 0.4 mm wide. A convex lens of focal length 0.8 m placed behind the slit focusses the light on a screen. What is the linear diameter of second maximum
|
(a) 6mm |
(b) 12 mm |
(c) 3 mm |
(d) 9 mm |
If in a nuclear fusion process the masses of the fusing nuclei be
and
and the mass of the resultant nucleus be
, then
|
(a) |
(b) |
(c) |
(d) |
Assertion : The lightening conductor at the top of high building has sharp pointed ends.
Reason : The surface density of charge at sharp points is very high resulting in setting up of electric wind.
|
(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. |
Stars are twinkling due to
|
(a) Diffraction |
(b) Reflection |
(c) Refraction |
(d) Scattering |