MCQ
In an A.C. circuit, the capacitive reactance is defined as __________ .
- A$Z _{ C }= j \omega C$
- B$Z _{ C }=-\frac{1}{j \omega C}$
- C$Z _{ C }=\frac{j}{\omega C}$
- ✓$Z _{ C }=\frac{1}{j \omega C}$
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A P-type semiconductor can be obtained by adding
|
(a) Arsenic to pure silicon |
(b) Gallium to pure silicon |
|
(c) Antimony to pure germanium |
(d) Phosphorous to pure germanium |
The colour of a star is an indication of its
|
(a) Weight |
(b) Distance |
(c) Surface temperature |
(d) Size |
An e.m.f. of 5 volt is produced by a self inductance, when the current changes at a steady rate from 3 A to 2 A in 1 millisecond. The value of self inductance is
|
(a) Zero |
(b) 5 H |
(c) 5000 H |
(d) 5 mH |
The ionization potential for second He electron is
|
(a) 13.6 eV |
(b) 27.2 eV |
(c) 54.4 eV |
(d) 100 eV |
The relative permeability is represented by mr and the susceptibility is denoted by c for a magnetic substance. Then for a paramagnetic substance
|
(a) mr < 1, c < 0 |
(b) mr < 1, c > 0 |
(c) mr > 1, c < 0 |
(d) mr > 1, c > 0 |
The plane faces of two identical plano-convex lenses each having focal length of 40 cm are pressed against each other to form a usual convex lens. The distance from this lens, at which an object must be placed to obtain a real, inverted image with magnification one is
|
(a) 80 cm |
(b) 40 cm |
(c) 20 cm |
(d) 162 cm |
In a potentiometer experiment the balancing with a cell is at length 240 cm. On shunting the cell with a resistance of 2 W, the balancing length becomes 120 cm. The internal resistance of the cell is
|
(a) 4 W |
(b) 2 W |
(c) 1 W |
(d) 0.5 W |