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Chapter 4: Moving Charges and Magnetism (Level 0 - Foundation)
Student Name: ____________________________________ Class: 12 Subject: Physics
Topic 4.1: Magnetic Force
1.
(MCQ) The formula for the magnetic force $\vec{F_m}$ on a charge $q$ moving with velocity $\vec{v}$ in a magnetic field $\vec{B}$ is:
(a) $q(\vec{v} \cdot \vec{B})$
(b) $q(\vec{v} \times \vec{B})$
(c) $q(\vec{B} \times \vec{v})$
(d) $\frac{q}{(\vec{v} \times \vec{B})}$
2.
(MCQ) Lorentz force acting on a moving charge is the vector sum of:
(a) Electric and Nuclear force
(b) Magnetic and Gravitational force
(c) Electric and Magnetic force
(d) Frictional and Magnetic force
3.
(MCQ) The trajectory of a charged particle entering perpendicularly into a uniform magnetic field is:
(a) Straight line
(b) Parabola
(c) Helical
(d) Circular
4.
(Fill in the blank) The SI unit of magnetic field ($\vec{B}$) is ____________.
5.
(Fill in the blank) The work done by a purely magnetic force on a moving charge is always ____________.
6.
(Fill in the blank) If a charged particle moves parallel to the magnetic field, the magnetic force acting on it is ____________.
7.
(One Word) What is the shape of the path taken by a charge moving at an acute angle ($\theta \neq 90^\circ$) to a uniform magnetic field?
8.
(One Word) Which hand rule is commonly used to find the direction of magnetic force on a moving positive charge?
9.
(Formula) Write the formula for the radius ($r$) of the circular path of a charge $q$ moving perpendicular to magnetic field $B$ with velocity $v$.
10.
(Formula) Write the formula for the time period ($T$) of a charge undergoing circular motion in a uniform magnetic field.
Topic 4.2: Magnetic Field due to Current (Biot-Savart Law)
11.
(MCQ) According to Biot-Savart Law, the magnetic field $dB$ due to a current element $Idl$ is directly proportional to:
(a) Current $I$ only
(b) $\sin\theta$ only
(c) Both $I$ and $\sin\theta$
(d) Distance $r^2$
12.
(MCQ) The magnetic field at the center of a circular current-carrying loop of radius $R$ is given by:
(a) $\frac{\mu_0 I}{2R}$
(b) $\frac{\mu_0 I}{2\pi R}$
(c) $\frac{\mu_0 I}{4\pi R}$
(d) $\frac{\mu_0 I^2}{2R}$
13.
(MCQ) In the formula for Biot-Savart law, the constant $\mu_0$ is known as:
(a) Permittivity of free space
(b) Permeability of free space
(c) Magnetic flux
(d) Dielectric constant
14.
(Fill in the blank) The numerical value of $\frac{\mu_0}{4\pi}$ in SI units is ____________ $T \cdot m/A$.
15.
(Fill in the blank) The direction of the magnetic field due to a straight current-carrying wire is found using the Right-Hand ____________ Rule.
16.
(Fill in the blank) The magnitude of the magnetic field due to a straight infinitely long wire at a perpendicular distance $r$ is $B = $ ____________.
17.
(True/False) The magnetic field at the center of a circular coil is inversely proportional to its radius.
18.
(True/False) Biot-Savart law for magnetism is mathematically analogous to Coulomb's law for electrostatics.
19.
(One Word) Write the SI unit of permeability ($\mu_0$).
20.
(Formula) Write the formula for the magnetic field on the axis of a circular loop of radius $R$ at a distance $x$ from its center.
Topic 4.3: Ampere’s Circuital Law
21.
(Match the following A to E with 1 to 5)
A. $\oint \vec{B} \cdot d\vec{l}$1. $\mu_0 n I$
B. Magnetic field inside an ideal solenoid2. Zero
C. Magnetic field outside an ideal toroid3. $\mu_0 I_{enclosed}$
D. Magnetic field due to a long straight wire4. $\frac{\mu_0 N I}{2\pi r}$
E. Magnetic field inside a toroid core5. $\frac{\mu_0 I}{2\pi r}$
22.
(Fill in the blank) Ampere's circuital law is particularly useful for calculating magnetic fields for ____________ current distributions.
23.
(Fill in the blank) A ____________ is essentially a long wire wound in the form of a closely spaced helix.
24.
(Fill in the blank) The magnetic field lines inside a tightly wound, ideal current-carrying solenoid are ____________ to its axis.
25.
(True/False) The magnetic field immediately outside an ideal, infinitely long solenoid is considered to be zero.
26.
(True/False) Ampere's Law relates the line integral of magnetic field to the total charge enclosed by the loop.
27.
(One Word) A toroid can be visualized as a solenoid bent into the shape of a ____________.
28.
(One Word) In the formula $B = \mu_0 n I$ for a solenoid, what does '$n$' represent?
29.
(Formula) State the mathematical expression for Ampere's Circuital Law.
30.
(Formula) Write the formula for the magnetic field at one of the ends of a long solenoid.
Topic 4.4: Force between Two Parallel Currents
31.
(MCQ) Two long parallel wires carrying currents in the same direction will:
(a) Attract each other
(b) Repel each other
(c) Have no effect on each other
(d) Rotate perpendicular to each other
32.
(MCQ) Two long parallel wires carrying currents in opposite directions will:
(a) Attract each other
(b) Repel each other
(c) Cancel each other's magnetic field completely
(d) Generate an electric field
33.
(MCQ) The force per unit length between two parallel wires separated by distance $d$ is:
(a) $\frac{\mu_0 I_1 I_2}{d}$
(b) $\frac{\mu_0 I_1 I_2}{2\pi d}$
(c) $\frac{\mu_0 I_1 I_2}{4\pi d}$
(d) $\frac{\mu_0 I_1 I_2}{d^2}$
34.
(Fill in the blank) The standard SI unit of current, one ____________, is defined based on the magnetic force between two parallel wires.
35.
(Fill in the blank) To define 1 Ampere, the two straight, infinitely long parallel wires are placed ____________ meter apart in a vacuum.
36.
(Fill in the blank) The defined force per unit length for 1 Ampere of current is exactly ____________ $N/m$.
37.
(One Word) What is the nature of the magnetic force between two parallel wires carrying anti-parallel currents?
38.
(True/False) The magnitude of the force on a straight wire of length $L$ carrying current $I$ in a uniform magnetic field $B$ is given by $F = I L B \sin\theta$.
39.
(True/False) Fleming's Left-Hand rule can be used to find the direction of the magnetic force on a current-carrying conductor.
40.
(Formula) Write the vector formula for the magnetic force on a straight conductor of length vector $\vec{l}$ carrying current $I$ in magnetic field $\vec{B}$.
Topic 4.5: Torque on a Current Loop
41.
(MCQ) The magnetic dipole moment $\vec{m}$ of a current loop carrying current $I$ with area vector $\vec{A}$ and $N$ turns is:
(a) $I \vec{A}$
(b) $N I \vec{A}$
(c) $\frac{N I}{\vec{A}}$
(d) $N^2 I \vec{A}$
42.
(MCQ) The torque $\vec{\tau}$ on a magnetic dipole $\vec{m}$ placed in a uniform magnetic field $\vec{B}$ is:
(a) $\vec{m} \cdot \vec{B}$
(b) $\vec{m} \times \vec{B}$
(c) $\vec{B} \times \vec{m}$
(d) $\frac{\vec{m}}{\vec{B}}$
43.
(MCQ) The SI unit of magnetic dipole moment is:
(a) $A \cdot m$
(b) $A \cdot m^2$
(c) $T \cdot m^2$
(d) $A/m^2$
44.
(Fill in the blank) A current-carrying planar loop behaves like a magnetic ____________.
45.
(Fill in the blank) For an electron revolving in a circular orbit, the constant ratio of its magnetic moment to its orbital angular momentum is called the ____________ ratio.
46.
(Fill in the blank) The torque on a current loop is maximum when the plane of the loop is ____________ to the uniform magnetic field.
47.
(True/False) The net translational magnetic force on any closed current loop placed in a uniform magnetic field is always zero.
48.
(True/False) A magnetic dipole is in stable equilibrium when its magnetic moment $\vec{m}$ is anti-parallel to the external magnetic field $\vec{B}$.
49.
(One Word) What is the name of the fundamental unit of magnetic moment associated with an electron due to its orbital motion? (Hint: _____ Magneton)
50.
(Formula) Write the formula relating magnetic moment ($\mu_l$) and angular momentum ($L$) for a revolving electron.
Topic 4.6: Moving Coil Galvanometer
51.
(MCQ) The principle of a moving coil galvanometer is based on:
(a) Heating effect of current
(b) Torque exerted on a current-carrying loop in a magnetic field
(c) Electromagnetic induction
(d) Force between two parallel wires
52.
(MCQ) To provide a radial magnetic field in a galvanometer, we use:
(a) Flat magnetic poles
(b) Cylindrical soft iron core and concave pole pieces
(c) A straight solenoid
(d) Non-magnetic core
53.
(MCQ) To convert a galvanometer into an ammeter, we connect:
(a) A high resistance in series
(b) A low resistance in series
(c) A low resistance (shunt) in parallel
(d) A high resistance in parallel
54.
(Fill in the blank) To convert a galvanometer into a voltmeter, we must connect a ____________ resistance in ____________ with the galvanometer.
55.
(Fill in the blank) The ____________ sensitivity of a galvanometer is defined as the deflection produced per unit current.
56.
(Fill in the blank) Voltage sensitivity is equal to current sensitivity divided by the ____________ of the galvanometer.
57.
(True/False) Increasing the number of turns in the coil always increases the voltage sensitivity of the galvanometer.
58.
(One Word) What material is typically used to make the suspension strip or hairspring in a galvanometer to provide the restoring torque?
59.
(One Word) The term '$k$' in the galvanometer equation $NIAB = k\theta$ represents the restoring torque per unit ____________.
60.
(Formula) Write the formula for the Current Sensitivity ($I_s$) of a moving coil galvanometer.
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