Using a bar magnet P, a vibration magnetometer has time period 2seconds. When a bar Q (identical to P in mass and size) is placed on top of P, the time period is unchanged. Which of the following statements is true
| (a) Q is of non-magnetic material |
|
(b) Q is a bar magnet identical to P, and its north pole placed on top of P's north pole |
| (c) Q is of unmagnetized ferromagnetic material |
| (d) Nothing can be said about Q's properties |
(b) Q is a bar magnet identical to P, and its north pole placed on top of P's north pole
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Two long straight wires are set parallel to each other. Each carries a current i in the same direction and the separation between them is 2r. The intensity of the magnetic field midway between them is
|
(a) |
(b) 4 |
(c) Zero |
(d) |
A star emitting radiation at a wavelength of 5000 Å is approaching earth with a velocity of 1.5
. The change in wavelength of the radiation as received on the earth, is
|
(a) 25 Å |
(b) Zero |
(c) 100 Å |
(d) 2.5 Å |
Ray optics fails when
|
(a) The size of the obstacle is 5 cm |
|
(b) The size of the obstacle is 3 cm |
|
(c) The size of the obstacle is less than the wavelength of light |
|
(d) (a) and (b) both |
A presbyopic patient has near point as 30 cm and far point as 40 cm. The dioptric power for the corrective lens for seeing distant objects is
|
(a) 40 D |
(b) 4 D |
(c) – 2.5 D |
(d) 0.25 D |
α - particles of energy 400 KeV are bombarded on nucleus of 
. In scattering of α - particles, its minimum distance from nucleus will be
|
(a) 0.59 nm |
(b) 0.59 Å |
(c) 5.9 pm |
(d) 0.59 pm |
Half lives of two radioactive substances A and B are respectively 20 minutes and 40 minutes. Initially the sample of A and B have equal number of nuclei. After 80 minutes, the ratio of remaining number of A and B nuclei is
|
(a) 1 : 16 |
(b) 4 : 1 |
(c) 1 : 4 |
(d) 1 : 1 |
