A bar magnet has coercivity 4 
. It is desired to demagnetise it by inserting it inside a solenoid 12 cm long and having 60 turns. The current that should be sent through the solenoid is
|
(a) 2 A |
(b) 4 A |
(c) 6 A |
(d) 8 A |
(d) 8 A
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100 cells each of e.m.f. 5 V and internal resistance 1 ohm are to be arranged so as to produce maximum current in a 25 ohms resistance. Each row is to contain equal number of cells. The number of rows should be
|
(a) 2 |
(b) 4 |
(c) 5 |
(d) 10 |
An alpha particle is accelerated through a potential difference of 
. Its kinetic energy will be
|
(a) 1 MeV |
(b) 2 MeV |
(c) 4 MeV |
(d) 8 MeV |
In Young's double slit experiment, the fringe width is 1 
if the distance between the slit and screen is doubled and the distance between the two slit is reduced to half and wavelength is changed from 6.4 
to , 4.0 
, the value of new fringe width will be
|
(a) 0.15 |
(b) 2.0 |
(c) 1.25 |
(d) 2.5 |
When NPN transistor is used as an amplifier
|
(a) Electrons move from base to emitter |
|
(b) Electrons move from emitter to base |
|
(c) Electrons moves from base to emitter |
|
(d) Holes moves from base to emitter |