Class 12 Moving Charges And Magnetism CBSE Questions & Answers

Class 12 · Moving Charges And Magnetism

This is Physics Class 12 Moving Charges and Magnetism CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
A wire is perpendicular to the plane of the paper. A ring of compass needles surrounds the wire in the plane of the paper with center of ring being the center of the wire .Initially there is no current in the wire. What happens after a steady dc current is established in the wire?
  • A
    The needles become parallel to each other
  • B
    some needles become parallel to each other while others are uneffected
  • C
    nothing happens
  • D
    The needles become tangential to the ring of which they are a part
    Correct
2
Which of the following is most general charachteristic of Magnetic field
  • A
    The magnetic field exerts a force {/tex}\vec{F}{/tex} on any other particle
  • B
    The magnetic field exerts a force \(\vec{F}\) on any other moving charge or current that is present in the field.
    Correct
  • C
    The magnetic field exerts a force \(\vec{F}\) only on any iron filings
  • D
    The magnetic field exerts a force \(\vec{F}\) only on any magnets present in the field.
3
which of the following best describes the difference between electric and magnetic fields
  • A
    The electric force acts on positive charges in the electric field, whereas the magnetic force acts on negative charges in the magnetic field
  • B
    The electric force acts on negative charges in the electric field, whereas the magnetic force acts on positive charges in the magnetic field
  • C
    The electric force acts in the direction perpendicular to electric field, whereas the magnetic force acts parallel to the magnetic field
  • D
    The electric force acts in the direction of the electric field, whereas the magnetic force acts perpendicular to the magnetic field
    Correct
4
Which of these equations is the correct expression for force on a charge in magnetic field
  • A
    \(\vec{F} = 3q\vec{v}×\vec{B}\)
  • B
    \(\vec{F} = q^2\vec{v}×\vec{B}\)
  • C
    \(\vec{F} = q\vec{v}×\vec{B}\)
    Correct
  • D
    \(\vec{F} = q\vec{v}×2\vec{B}\)
5
direction of magnetic force on a positive charge moving in a magnetic field is given by
  • A
    thumb rule
  • B
    left hand rule
  • C
    two hand rule
  • D
    right hand rule
    Correct
6
Lorentz Force generally refers to
  • A
    force experienced by a charge due to combined action of electrical,magnetic field and gravitational field
  • B
    force experienced by a charge due to combined action of electrical fields
  • C
    force experienced by a charge due to combined action of electrical and magnetic fields
  • D
    force experienced by a charge due to action of magnetic fields
    Correct
7
correct unit of magnetic field is
  • A
    Amperes
  • B
    Tesla
    Correct
  • C
    Newton coulombs
  • D
    ampere turns
8
If a current I is flowing in a staight wire parallel to x axis and magnetic field is there in the y axis then
  • A
    The wire experiences force in x direction
  • B
    The wire experiences force in y direction
  • C
    The wire experiences no force
  • D
    The wire experiences force in z direction
    Correct
9
correct expression for force on a current carrying conductor of length dl in a magnetic field is
  • A
    \(\vec{F} = \epsilon_0 I\vec{dl}×\vec{B}\)
  • B
    \(\vec{F} = 2I\vec{dl}×\vec{B}\)
  • C
    \(\vec{F} = I\vec{dl}×\vec{B}\)
    Correct
  • D
    \(\vec{F} = I\vec{dl}×2\vec{B}\)
10
The magnitude of the magnetic field due to a circular coil of radius R carrying a current I at an axial distance x from the centre is
  • A
    \(B =\frac{\mu_0IR^2}{2(x^2 + R^2)^{\frac{3}{2}}}\)
    Correct
  • B
    \(B =\frac{\mu_0IR^3}{2(x^2 + R^2)^{\frac{3}{2}}}\)
  • C
    \(B =\frac{\mu_0IR^2}{2(x^2 + R^2)^{\frac{3}{5}}}\)
  • D
    \(B =\frac{\mu_0IR^2}{3(x^2 + R^2)^{\frac{3}{2}}}\)
11
Consider the motion of a charged particle in a uniform magnetic field directed into the paper.If velocity v of the particle is in the plane of the paper the charged particle will
  • A
    describe an ellipse
  • B
    describe a circle
    Correct
  • C
    describe a straight line
  • D
    describe a hyperbola
12
cyclotron is used to
  • A
    decelerate charged particles or ions to high voltages
  • B
    accelerate charged particles or ions to high energies
    Correct
  • C
    accelerate charged particles or ions to low voltages
  • D
    accelerate charged particles or ions to high voltages
13
cyclotron frequency of a charged particle having charge q and mass m in a cyclotron producing magnetic field B is
  • A
    \(\frac{qB}{\pi m}\)
  • B
    \(\frac{qB^2}{2\pi m}\)
  • C
    \(\frac{qB}{2\pi m}\)
    Correct
  • D
    \(\frac{q^2B}{2\pi m}\)
14
what is common to both biot savart law and ampere's law
  • A
    Both relate the magnetic field and the current, and both express the same physical consequences of a varying electrical current
  • B
    nothing in common
  • C
    Both relate the magnetic field and the current, and both express the same physical consequences of a steady electrical current
    Correct
  • D
    Both relate the magnetic field and the current density, and both express the same physical consequences of a steady electrical current
15
According to Ampere's circuital law
  • A
    \( \oint \vec{B}. \vec{dl} = \mu_0 I\)
    Correct
  • B
    \( \oint \vec{B} . \vec{dl} = I\)
  • C
    \( \oint \vec{B} . \vec{dl} = \pi\mu_0 I\)
  • D
    \( \oint \vec{B} . \vec{dl} = 2\pi\mu_0 I\)