Physics-
General
Easy
Question
PQ and RS are long parallel conductors separated by certain distance. M is the mid-point between them (see the figure). The net magnetic field at M is B. Now, the current 2A is switched off. The field at M now becomes

- 2B
- B
- 3B
The correct answer is: B
Magnetic field at mid-point
in first case is 


When the current 2 A is switched off, the net magnetic field at
is due to current 1 A

Related Questions to study
physics-
Current through ABC and A’ B’ C’ is I. What is the magnetic field at P?
(Here C’ B’ PBC are collinear)

Current through ABC and A’ B’ C’ is I. What is the magnetic field at P?
(Here C’ B’ PBC are collinear)

physics-General
physics
The ratio of pathlength and the respective time interval is
The ratio of pathlength and the respective time interval is
physicsGeneral
physics
A particle is thrown in upward direction with initial velocity of 60 m/s. Find average speed and average velocity after 10 seconds. [g =10 MS2]
A particle is thrown in upward direction with initial velocity of 60 m/s. Find average speed and average velocity after 10 seconds. [g =10 MS2]
physicsGeneral
physics-
The work done in deforming body is given by
The work done in deforming body is given by
physics-General
physics-
A wire of length
and radius
is stretched between
and
without the application of any tension. If
is the Young’s modulus of the wire and it is stretched like
, then the tension in the wire will be

A wire of length
and radius
is stretched between
and
without the application of any tension. If
is the Young’s modulus of the wire and it is stretched like
, then the tension in the wire will be

physics-General
physics-
A cube of aluminium of sides 0.1 m is subjected to a sharing force of 100 N. The top face of the cube is displaced through 0.02 cm with respect to the bottom face. The shearing strain would be
A cube of aluminium of sides 0.1 m is subjected to a sharing force of 100 N. The top face of the cube is displaced through 0.02 cm with respect to the bottom face. The shearing strain would be
physics-General
physics-
A uniform slender rod of length L, cross-sectional area A and Young’s modulus Y is acted upon by the forces shown in the figure. The elongation of the rod is

A uniform slender rod of length L, cross-sectional area A and Young’s modulus Y is acted upon by the forces shown in the figure. The elongation of the rod is

physics-General
physics-
The graph shows the behaviour of a length of wire in the region for which the substance obeys Hooke’s law.
and
represent

The graph shows the behaviour of a length of wire in the region for which the substance obeys Hooke’s law.
and
represent

physics-General
physics-
If the shear modulus of a wire material is 5.9
then the potential energy of a wire of
in diameter and 5 cm long twisted through an angle of 10’ , is
If the shear modulus of a wire material is 5.9
then the potential energy of a wire of
in diameter and 5 cm long twisted through an angle of 10’ , is
physics-General
physics-
The Young’s modulus of the material of a wire is equal to the
The Young’s modulus of the material of a wire is equal to the
physics-General
Maths-
Maths-General
physics-
Two short bar magnets of equal dipole moment M are fastened perpendicularly at their centers, figure. The magnitude of resultant of two magnetic field at a distance
from the center on the bisector of the right angle is

Two short bar magnets of equal dipole moment M are fastened perpendicularly at their centers, figure. The magnitude of resultant of two magnetic field at a distance
from the center on the bisector of the right angle is

physics-General
physics-
Two magnets of equal mass are joined at 90
each other as shown in figure. Magnet
has a magnetic moment
times that of
. The arrangement is pivoted so that it is free to rotate in horizontal plane. When in equilibrium, what angle should
make with magnetic meridian?

Two magnets of equal mass are joined at 90
each other as shown in figure. Magnet
has a magnetic moment
times that of
. The arrangement is pivoted so that it is free to rotate in horizontal plane. When in equilibrium, what angle should
make with magnetic meridian?

physics-General
physics-
The pressure applied from all directions on a cube is
. How much its temperature should be raised to maintain the original volume? The volume elasticity of the cube is
and the coefficient of volume expansion is 
The pressure applied from all directions on a cube is
. How much its temperature should be raised to maintain the original volume? The volume elasticity of the cube is
and the coefficient of volume expansion is 
physics-General
physics-
A wire
has length 1 m and cross-sectional area 1
The work required to increase the length by 2 mm is
A wire
has length 1 m and cross-sectional area 1
The work required to increase the length by 2 mm is
physics-General