- APhosphorus.
- BBoron.
- CAntimony.
- DAluminium.
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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The current in a simple series circuit is 5.0 amp. When an additional resistance of 2.0 ohms is inserted, the current drops to 4.0 amp. The original resistance of the circuit in ohms was
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(a) 1.25 |
(b) 8 |
(c) 10 |
(d) 20 |
An astronomical refractive telescope has an objective of focal length 20m and an eyepiece of focal length 2cm.
Assertion : X-rays are used for studying the structure of crystals.
Reason : The distance between the atoms of crystals is of the order of wavelength of X-rays.
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(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
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(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
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(c) If assertion is true but reason is false. |
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(d) If the assertion and reason both are false. |
The variation of potential with distance R from a fixed point is as shown below. The electric field at R = 5 m is
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(a) 2.5 volt/m |
(b) -2.5 volt/m |
(c) 2/5 volt/m |
(d) -2/5 volt/m |
A 10 pF capacitor is connected to a 50 V battery. How much electrostatic energy is stored in the capacitor
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(a) 1.25 |
(b) 2.5 |
(c) 3.5 |
(d) 4.5 |
What will be the height of image when an object of 2 mm is placed on the axis of a convex mirror at a distance 20 cm of radius of curvature 40 cm
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(a) 20 mm |
(b) 10 mm |
(c) 6 mm |
(d) 1 mm |