- AThe direction of current is always positive
- BThe direction of current is always negative
- CThe direction of current changes constantly
- DThe direction of current is either positive or negative
Explanation:
Electric charge in alternating current (AC) changes direction periodically. The voltage in AC circuits also periodically reverses because the current changes direction.
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The energy that should be added to an electron to reduce its de Broglie wavelength from one nm to 0.5 nm is
|
(a) Four times the initial energy |
(b) Equal to the initial energy |
|
(c) Twice the initial energy |
(d) Thrice the initial energy |
In order to increase the sensitivity of a moving coil galvanometer, one should decrease
|
(a) The strength of its magnet |
(b) The torsional constant of its suspension |
|
(c) The number of turns in its coil |
(d) The area of its coil |
A achromatic combination is made with a lens of focal length f and dispersive power ω with a lens having dispersive power of 2ω. The focal length of second will be
|
(a) 2f |
(b) f/2 |
(c) -f/2 |
(d) – 2 f |
A galvanometer can be converted into an ammeter by connecting
|
(a) Low resistance in series |
(b) High resistance in parallel |
|
(c) Low resistance in parallel |
(d) High resistance in series |
In a circuit 5 percent of total current passes through a galvanometer. If resistance of the galvanometer is G then value of the shunt is
|
(a) 19 G |
(b) 20 G |
(c) |
(d) |