- ADecreases directly as the distance from the centre.
- BIncreases directly as the distance from the centre.
- CRemains constant.
- DNone of these.
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X-rays are not used for radar purpose because
| (a) They are not reflected by the target |
| (b) They are not electromagnetic waves |
| (c) They are completely absorbed by the air |
| (d) They sometimes damage the target |

A man cannot see clearly the objects beyond a distance of 20 cm from his eyes. To see distant objects clearly he must use which kind of lenses and of what focal length
|
(a) 100 cm convex |
(b) 100 cm concave |
(c) 20 cm convex |
(d) 20 cm concave |
In the circuit shown here, the readings of the ammeter and voltmeter are
|
(a) 6 A, 60 V |
(b) 0.6 A, 6 V |
(c) 6/11 A, 60/11 V |
(d) 11/6 A, 11/60 V |
Atomic weight of boron is 10.81 and it has two isotopes
and
. Then ratio of
in nature would be
|
(a) 19 : 81 |
(b) 10 : 11 |
(c) 15 : 16 |
(d) 81 : 19 |
A point Q lies on the perpendicular bisector of an electrical dipole of dipole moment p. If the distance of Q from the dipole is r (much larger than the size of the dipole), then electric field at Q is proportional to
|
(a) |
(b) p and |
(c) |
(d) p and |
Direction of the first secondary maximum in the Fraunhofer diffraction pattern at a single slit is given by (a is the width of the slit)
|
(a) asinθ = |
(b) acosθ = |
(c) asinθ = |
(d) asinθ = |