JEE Main Physics - Magnetic Effects of Currents
Exam Duration: 60 Mins Total Questions : 30
An electron is injected into a region of uniform magnetic field of induction with its velocity inclined to the field. The path of the electron is a
- (a)
circle
- (b)
parabola
- (c)
linear
- (d)
helix
A circular coil carrying current has magnetic induction B at its centre C. The radius of the coil is 3 cm. The distance of a point P from C, where the induction reduces to \(\frac { B }{ 8 } \) would be
- (a)
\(\sqrt { 3 } \)
- (b)
2\(\sqrt { 3 } \)
- (c)
3\(\sqrt { 3 } \)
- (d)
9
The electron of Bohr orbit of hydrogen atom revolves in its innermost orbit round the proton. The magnetic induction at the proton is of the order of
- (a)
1 T
- (b)
10 T
- (c)
100 T
- (d)
1000 T
The magnetic field at the centre of a circular coil carrying current is
- (a)
smaller, smaller the radius of the coil
- (b)
greater, smaller the radius of the coil
- (c)
directly proportional to the cube of the radius
- (d)
inversely proportional to the cube of the radius
If h and e denote Planck's constant and electronic charge respectively, then h/e has unit of
- (a)
magnetic flux
- (b)
magnetic flux density
- (c)
electric flux
- (d)
electric flux density
A plane loop, carrying a current is placed in a uniform magnetic field. It will experience
- (a)
a resultant torque but no resultant force
- (b)
a result force but no resultant torque
- (c)
a resultant force as well as a torque
- (d)
neither resultant force nor torque
An electrical instrument P is connected in series with a galvanometer G. A small resistance placed
- (a)
parallel with G will increase the sensitivity of P
- (b)
parallel with G will reduce the sensitivity of P
- (c)
in series with G will change the sensitivity of P
- (d)
in series with P will change the sensitivity of both P and G
A cell is connected between two points of a uniformly thick circular conductor. i1 and i2 are the currents flowing in two parts of the circular conductor of radius a. The magnetic field at the centre of the loop will be
- (a)
zero
- (b)
\(\frac { { \mu }_{ 0 } }{ 4\pi } \left( { i }_{ 1 }-{ i }_{ 2 } \right) \)
- (c)
\(\frac { { \mu }_{ 0 } }{ 2a } \left( { i }_{ 1 }+{ i }_{ 2 } \right) \)
- (d)
\(\frac { { \mu }_{ 0 } }{ 2a } \left( { i }_{ 1 }+{ i }_{ 2 } \right) \)
A proton and an electron both moving with the same velocity \(\vartheta \) enter into region of magnetic field directed perpendicular to the velocity of the particles. They will now move in circular orbits such that
- (a)
their time periods will be same
- (b)
the time period for proton will be higher
- (c)
the time period for electron will be higher
- (d)
their orbital radii will be the same
XA proton of mass 1.67X10-27 kg and charge 1.6X10-19 is projected with a speed of 2X106 ms-1 at an angle 600 to the x-axis. If a uniform magnetic field of 0.104 tesla is applied along y-axis, the path of proton is
- (a)
a circle of radius = 0.2 m and time period = \(2\pi \times { 10 }^{ -7\quad }s\)
- (b)
a circle of radius = 0.1 m and time period = \(2\pi \times { 10 }^{ -7\quad }s\)
- (c)
a helix of radius = 0.1 m and time period =\(2\pi \times { 10 }^{ -7\quad }s\)
- (d)
a helix of radius = 0.2 m and time period =\(2\pi \times { 10 }^{ -7\quad }s\)
A particle of charge q mass m moves in a circular orbit of radius r with angular speed \(\omega \). The ratio of the magnitude of its magnetic moment to that of its angular momentum depends on
- (a)
\(\omega \) and q
- (b)
\(\omega \)q and m
- (c)
q and m
- (d)
\(\omega \) and m
A long straight, solid metal wire of radius 2 mm carries a current uniformly distributed over its circular cross-section. The magnetic field induction at a distance 2 mm from its axis is B. Then, the magnetic field induction at distance 1 mm from axis will be
- (a)
B
- (b)
B/2
- (c)
2B
- (d)
B
In a given figure, X and Y are two long straight parallel conductors each carrying a current of 2 A. The force on each conductor is F Newton. When the current in each is changed to 1 A and reversed in direction, the force on each is now
- (a)
F/4 and unchanged in direction
- (b)
F/2 and reversed in direction
- (c)
F/2 and unchanged in direction
- (d)
F/4 and reversed in direction
The magnitude of the magnetic field, due to the presence of the current i1 at the origin
- (a)
the forces on AB and DC are zero
- (b)
the forces on AD and BC are zero
- (c)
the magnitude of the net force on the loop is given by \(\frac { { \mu }_{ o }i{ i }_{ 1 } }{ 4\pi } \left[ 2(b-a)+\frac { \pi }{ 3 } (a+b) \right] \)
- (d)
the magnitude of the net force on the loop is given by \(\frac { { \mu }_{ o }i{ i }_{ 1 } }{ 24ab } (b-a)\)