- AElectric field.
- BMagnetic field.
- CNorth field.
- DAll.
Explanation:
Space surrounding a magnet in which magnetic force is executed, is called a magnetic field.
A magnetic field is a vector field that describes the magnetic influence of electrical currents and magnetized materials. In everyday life, the effects of magnetic fields are most readily encountered with nearby permanent magnets, which pull on magnetic materials (such as iron) and attract or repel other magnets.
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The circuit shown here is used to compare the e.m.f. of two cells and
. The null point is at C when the galvanometer is connected to
. When the galvanometer is connected to
, the null point will be
|
(a) To the left of C |
(b) To the right of C |
(c) At C itself |
(d) Nowhere on AB |
If a radioactive substance reduces to
of its original mass in 40 days, what is its half-life
|
(a) 10 days |
(b) 20 days |
(c) 40 days |
(d) None of these |
The frequencies of X-rays, g-rays and ultraviolet rays are respectively a, b and c. Then
|
(a) a < b, b > c |
(b) a > b, b > c |
(c) a > b, b < c |
(d) a < b, b < c |
The angle of dip at a place on the earth gives
|
(a) The horizontal component of the earth's magnetic field |
| (b) The location of the geographic meridian |
|
(c) The vertical component of the earth's field |
|
(d) The direction of the earth's magnetic field |
Assertion : V-i characteristic of P-N junction diode is same as that of any other conductor.
Reason : P-N junction diode behave as conductor at room temperature.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |

An α- particle travels in a circular path of radius 0.45 m in a magnetic field B = 1.2
with a speed of 2.6
. The period of revolution of the α - particle is
|
(a) 1.1 |
(b) 1.1 |
(c) 1.1 |
(d) 1.1 |
A concave lens of glass, refractive index 1.5, has both surfaces of same radius of curvature R. On immersion in a medium of refractive index 1.75, it will behave as a
|
(a) Convergent lens of focal length 3.5 R |
|
(b) Convergent lens of focal length 3.0 R |
|
(c) Divergent lens of focal length 3.5 R |
|
(d) Divergent lens of focal length 3.0 R |
The current in a simple series circuit is 5.0 amp. When an additional resistance of 2.0 ohms is inserted, the current drops to 4.0 amp. The original resistance of the circuit in ohms was
|
(a) 1.25 |
(b) 8 |
(c) 10 |
(d) 20 |