A rectangular loop carrying a current i1, is situated near a long straight carrying a straight current i2. The wire is parallel to one of the sides of the loop as shown in the figure. Then the current loop will
move away from the wire
move towards the wire
remain stationary
rotate about axis parallel to wire
B.
move towards the wire
As two like currents attract and unlike currents repel each other, the wire will attract the side A of the loop near the wire and parallel to it and the far side of the loop again parallel to the wire will be repelled. But the force of attraction will be more as that side of the loop is closer to the wire and so effectively the current loop will more towards the wire.
The maximum distance upto which TV transmission from a TV of height h can be received is proportional to
h1/2
h
h3
h2
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 ?
2 MHz
10 MHz
12 MHz
18 MHz
Using mass (M), length (L), time (T ) and current (A) as fundamental quantities, the dimension of permeability is
[ M-1 L T-2 A ]
[ M L2 T-2 A-1 ]
[ M L T-2A-2 ]
[ M L T-1 A-1 ]
A laser beam is used for carrying out surgery because it
is highly monochromatic
is highly coherent
is highly directional
can be sharply focused
A proton is about 1840 times heavier than an electron. When it is accelerated by a potential difference of 1 kV, its kinetic energy will be
1840 keV
1/1840 keV
1 keV
920 keV
To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave like
a conductor
a p-type semiconductor
an n-type semiconductor
an insulator
A radioactive substance decays to 1/16th of its initial activity in 40 days. The half-life of the radioactive substance expressed in days is
2.5
5
10
20
A neutron makes a head-on elastic collision with a stationary deuteron. The fractional energy loss of the neutron in the collision is
16/81
8/9
8/27
2/3
When a beam of light is used to determine the position of an object, the maximum accuracy is achieved if the light is
polarised
of longer wavelength
of shorter wavelength
of high intensity