- AMoving charge
- BChange in magnetic flux
- CCurrent flowing in conductor
- DStationary charge
Explanation:
Magnetic field is the magnetic effect of electric currents andmagnetic materials.
The magnetic field at any given point is specified by both a direction and a magnitude (or strength); as such it is represented by a vector field.
As magnetic field has both magnitude as well as direction so it is a vector quantity.When charges are stationary, their electric fields do not affect magnets.
But, when charges move, they produce magnetic fields that exert forces on other magnets.
When there is relative motion, a connection between electric and magnetic fields emerges—each affects the other.
Quantity that is not affected by magnetic field is Stationary charge.
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In short wave communication waves of which of the following frequencies will be reflected back by the ionospheric layer, having electron density 1011 per m3
|
(a) 2 MHz |
(b) 10 MHz |
(c) 12 MHz |
(d) 18 MHz |
A transmitter supplies 9 kW to the aerial when unmodulated. The power radiated when modulated to 40% is
|
(a) 5 kW |
(b) 9.72 kW |
(c) 10 kW |
(d) 12 kW |
A rectangular coil 20 cm × 20 cm has 100 turns and carries a current of 1 A. It is placed in a uniform magnetic field B = 0.5 T with the direction of magnetic field parallel to the plane of the coil. The magnitude of the torque required to hold this coil in this position is
|
(a) Zero |
(b) 200 N-m |
(c) 2 N-m |
(d) 10 N-m |
When phosphorus and antimony are mixed in zermaniun, then
|
(a) P-type semiconductor is formed |
(b) N-type semiconductor is formed |
|
(c) Both (a) and (b) |
(d) None of these |
An ionization chamber with parallel conducting plates as anode and cathode has 5
electrons and the same number of singly-charged positive ions per
. The electrons are moving at 0.4 m/s. The current density from anode to cathode is
. The velocity of positive ions moving towards cathode is
|
(a) 0.4 m/s |
(b) 16 m/s |
(c) Zero |
(d) 0.1 m/s |
A film projector magnifies a 100 cm2 film strip on a screen. If the linear magnification is 4, the area of magnified film on the screen is
|
(a) 1600 cm2 |
(b) 400 cm2 |
(c) 800 cm2 |
(d) 200 cm2 |