10 eV electron is circulating in a plane at right angle to a uniform field of magnetic induction 10-1 Wb/m² (1G). The orbital radius of electron is:
1.12 cm
2.16 cm
3.11 cm
4.18 cm
A charge + q is sent through a magnetic field. The force acting on it is maximum w hen the angle between the direction of motion of the charged particle and the magnetic field :
1.0°
2.45°
3.90°
4.180°
A current carring coil is placed in a uniform magnetic field. If the coil turns through an angle θ, then the torque is directly proportional to:
1. sin θ
2.cos θ
3.cot θ
4.tan θ
A current carrying power line carries current from west to east. Then the direction of the magnetic field 2 m above it is :
1.west to east
2. south to north
3.north to south
4.None of the above
A cyclotron can be used to produce high energy:
1.neutrons
2.deutrons
3.β particles
4.α partifcles
A wire of length 2 metre carries a current 1 ampere, is bent to form a circle. The magnetic moment of the coil is :
1. 2Ï€
2.Ï€/2
3.Ï€/4
4.1/Ï€
According to Gauss’s theorem in magnetism, surface integral of magnetic field intensity over a surface (closed or open) is always:
1.-1
2.1
3.0
4.infinity
Circular loop of radius 0.0157 m carries a current 2 A. The magnetic field at the centre of the loop is :
1.1.57 × 10-3Wb/m²
2.8.0 × 10-5 Wb/m²
3.2.0 × 10-3 Wb/m²
4.3.l4 × 10-1 Wb/m²
Earth’s magnetism was discovered by:
1.Gauss
2.Oersted
3.Ampere
4.Gilbert
Isoclinic lines are the lines joining places with :
1.equal dip
2.equal declination
3.equal dip and declination
4.None of the above
same everywhere
1. same everywhere
2. inversely proportional to the distance
3.directly proportional to the distance
4.None of the above
Tesla is a unit of:
1. electric flux
2. magnetic flux
3.magnetic field
4.electric field
The current sensitibility of a moving coil galanometer increases with decrease in:
1.magnetic field
2.area of a coil
3.number of turns
4.None of the above
The force between two parallel current carrying conductors is F. If the current in each conductor is doubled, then the force between them becomes :
1.4F
2.2F
3.F
4.F/4
The magnetic field of a given length of a ware for single turn coil at its centre is B. Then.its value for two turns of coil will be :
1.B/4
2.B/2
3.4B
4.2B
The most suitable metal for making permanent magnets is :
1.iron
2.steel
3.copper
4.aluminium
The permeability of a paramagnetic substance is:
1. very large
2. small but more than unity
3.less than unity
4.negative
The radius of the trajectory of a charged particle in a uniform magnetic field is proportional to the:
1.charge on the particle
2.energy of the particle
3.momentum of the particle
4.All the above
The sensitivity of a tangent galvanometer can be increased by increasing:
1.the radius of the coil
2.the external magnetic field
3. the number of turns of the coil
4.all the above
The SI unit of magnetic dipole moment is’
1.Ampere
2.Ampere metre²
3.Tesla
4.None of the above
The strength of the magnetic field around an infinite current carrying conductor is :
1.same everywhere
2.inversely proportional to the distance
3.directly proportional to the distance
4.None of the above
To convert galvanometer into voltmeter one should connect :
1.high resistance in series with galvanometer
2.low resistance in series with galvanometer
3.high resistance in parallel with galvanometer
4. low resistance in parallel with galvanometer
What happens to the magnetic field at the centre of a circular current carrying coil if we double the radius of the coil keeping the current unchanged?
1.halved
2.doubled
3.quadrupled
4.remains unchanged
What is the angle of dip at the magnetic poles ?
1. 30°
2.0°
3.45°
4.None of the above
When charged particle enters-a uniform magnetic field, its K.E.:
1. remains constant
2.increases
3.decreases
4.becomes zero
When we double the radius of a coil keeping the current through it unchanged, what happens to the magnetic field directed along its axis at far off points?
1.halved
2.doubled
3.quadrupled
4.remains unchanged
Which of the following is not a unit of magnetic induction?
1.gauss
2.tesla
3.oersted
4.weber/metre²
Which of the following shows that the earth behaves as a magnet?
1.Repulsion between like poles .
2.Attraction between unlike poles
3.Null points in the magnetic field of a bar magnet
4.No existence of isolated magnetic poles