Two capacitors C1 and C2 = 2C1 are connected in a circuit with a switch between them as shown in the figure. Initially the switch is open and C1 holds charge Q. The switch is closed. At steady state, the charge on each capacitor will be
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(a) Q, 2Q |
(b) Q/3, 2Q/3 |
(c) 3Q/2, 3Q |
(d) 2Q/3, 4Q/3 |
(b) Q/3, 2Q/3
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In an NPN transistor circuit, the collector current is 10 mA. If 90% of the electrons emitted reach the collector, the emitter current (iE) and base current (iB) are given by
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(a) iE = – 1 mA, iB = 9 mA |
(b) iE = 9 mA, iB = – 1 mA |
|
(c) iE = 1 mA, iB = 11 mA |
(d) iE = 11 mA, iB = 1 mA |
A Daniel cell is balanced on 125 cm length of a potentiometer wire. Now the cell is short-circuited by a resistance 2 ohm and the balance is obtained at 100 cm. The internal resistance of the Daniel cell is
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(a) 0.5 ohm |
(b) 1.5 ohm |
(c) 1.25 ohm |
(d) 4/5 ohm |
Two cells when connected in series are balanced on 8m on a potentiometer. If the cells are connected with polarities of one of the cell is reversed, they balance on 2m. The ratio of e.m.f.'s of the two cells is
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(a) 3 : 5 |
(b) 5 : 3 |
(c) 3 : 4 |
(d) 4 : 3 |
The capacity of a parallel plate condenser is 10μF without dielectric. Dielectric of constant 2 is used to fill half the distance between the plates, the new capacitance in μF is
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(a) 10 |
(b) 20 |
(c) 15 |
(d) 13.33 |
In a Young's double slit experiment the source S and the two slits A and B are vertical with slit A above slit B. The fringes are observed on a vertical screen K. The optical path length from S to B is increased very slightly (by introducing a transparent material of higher refractive index) and the optical path length from S to A is not changed, as a result the fringe system on K moves
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(a) Vertically downwards slightly |
(b) Vertically upwards slightly |
|
(c) Horizontally, slightly to the left |
(d) Horizontally, slightly to the right |
When one of the slits of Young’s experiment is covered with a transparent sheet of thickness 4.8 mm, the central fringe shifts to a position originally occupied by the 30th bright fringe. What should be the thickness of the sheet if the central fringe has to shift to the position occupied by 20th bright fringe
|
(a) 3.8 mm |
(b) 1.6 mm |
(c) 7.6 mm |
(d) 3.2 mm |