P-type semiconductor is formed when
A. As impurity is mixed in Si B. Al impurity is mixed in Si
C. B impurity is mixed in Ge D. P impurity is mixed in Ge
|
(a) A and C |
(b) A and D |
(c) B and C |
(d) B and D |
(c) B and C
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Assertion : For cooking in a microwave oven, food is always kept in metal containers.
Reason : The energy of microwave is easily transferred to the food in metal container.
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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. |
A cell of internal resistance 1.5Ω and of e.m.f. 1.5 volt balances 500 cm on a potentiometer wire. If a wire of 15 Ω is connected between the balance point and the cell, then the balance point will shift
|
(a) To zero |
(b) By 500 cm |
(c) By 750 cm |
(d) None of the above |
The minimum frequency v of continuous X-rays is related to the applied potential difference V as
|
(a) v ∝ |
(b) v ∝ v |
(c) v ∝ |
(d) v ∝ |
A 50 volt potential difference is suddenly applied to a coil with 
henry and R = 180 ohm. The rate of increase of current after 0.001 second is
|
(a) 27.3 amp/sec |
(b) 27.8 amp/sec |
(c) 2.73 amp/sec |
(d) None of the above |
Taking Rydberg’s constant 
first and second wavelength of Balmer series in hydrogen spectrum is
| (a) 2000 Å, 3000 Å | (b) 1575 Å, 2960 Å | (c) 6529 Å, 4280 Å | (d) 6552 Å, 4863 Å |
The characteristic impedance of a coaxial cable is of the order of
|
(a) 50 W |
(b) 200 W |
(c) 270 W |
(d) None of these |
