intro
Question 1:
What does a magnetic field alter in a moving charged particle?
Topic: Magnetic Fields and Charged Particles
Correct Answer: B) Trajectory
- The role of magnetic fields on charged particles primarily involves altering their path or trajectory.
- Magnetic forces are deflective; they do not change the particle's speed or energy, only its direction.
- Hence, the correct answer is B, "Trajectory".
Question 2:
What is the charge-to-mass ratio of an electron?
Topic: Charge-to-Mass Ratio of Electron
Correct Answer: A) 1.7588 × 1011 C/kg
- The charge-to-mass ratio (e/m) of an electron is a characteristic value.
- The correct ratio is 1.7588 × 1011 C/kg.
- Hence, the correct answer is A, "1.7588 × 1011 C/kg".
Question 3:
What path does a charged particle follow when entering a uniform magnetic field perpendicularly?
Topic: Magnetic Fields and Charged Particles
Correct Answer: B) A circle
- A charged particle experiences a constant force when it enters a magnetic field perpendicularly.
- The path followed is a circle.
- Hence, the correct answer is B, "A circle".
Question 4:
Given a magnetic field of B = 40i + 8k Wb/m2, how much flux is passing through a plane of area 5 m2 in the xy plane?
Topic: Magnetic Flux through a Plane
Correct Answer: A) 40 Wb
- It is possible to calculate magnetic flux by taking the dot product of the area vector (A) and the magnetic field vector (B), then multiplying the result by the amount of flux.
- In this case, B = 40i + 8k and A = 5k. The dot product results in 40 Wb.
- Hence, the correct answer is A, "40 Wb".
Question 5:
What is the effect between two parallel wires carrying current in the same direction?
Topic: Electromagnetic Interactions
Correct Answer: C) They attract each other
- Currents flowing in parallel create magnetic fields that interact when the wires are parallel.
- This interaction results in an attractive force between the wires.
- Hence, the correct answer is C, "They attract each other".
Question 6:
What is represented by the equation F = Fe + Fm?
Topic: Lorentz Force and Charged Particles
Correct Answer: C) Lorentz force
- The formula F = Fe + Fm represents the Lorentz force, the total force experienced by a charged particle in an electromagnetic field.
- A charged particle in a magnetic field is affected by the sum of electric and magnetic forces.
- Hence, the correct answer is C, "Lorentz force".
Question 7:
What is the unit for the “E/B” ratio?
Topic: Electric and Magnetic Field Ratios
Correct Answer: C) Meters per second (ms^-1)
- The ratio of E (Electric Field Strength) over B (Magnetic Flux Density) has a unit of velocity, represented as meters per second (ms^-1).
- It's used to measure the speed of a charged particle in an electromagnetic field.
- Hence, the correct answer is C, "Meters per second (ms^-1)".
Question 8:
What is the equation for the force experienced by a charged particle with charge 'e', moving with velocity 's', in a magnetic field 'B'?
Topic: Magnetic Field Forces on Moving Charges
Correct Answer: D) F = e (s x B)
- Magnetic fields exert force on moving charges according to the equation F = e (s x B).
- 's' represents the velocity of the charge.
- 'e' represents the charge.
- 'B' represents the magnetic field.
- Both the magnetic field and the charge's velocity are perpendicular to the cross product (s x B).
MCQs 9:
The illustration demonstrates three configurations of circular loops, aligned on vertical axes and conducting identical currents in the specified directions. Rank the configurations based on the magnitudes of the magnetic fields at the midpoints between the loops on the central axes.
Topic: Magnetic Fields of Loop Configurations
Correct Answer: B) 2,3,1
- The magnitude of the magnetic field at the midpoint between the loops on the central axes depends on the direction of the current and the positioning of the loops.
- The correct order, based on magnitude, is 2, 3, 1.
MCQs 10:
What is the magnetic force on an electron moving at 10^6 ms^-1 parallel to the field of strength 1wb m^-2?
Topic: Magnetic Force on an Electron
Correct Answer: D) Zero
- It is impossible for a charged particle to be affected by a magnetic field when it moves parallel to it.
- This is because the magnetic force is given by F = qvBsinθ.
- When the particle moves parallel to the field, θ = 0°.
- Hence, the sin0° = 0, making the entire force zero.
Question 11:
What is the standard international (S.I) unit for magnetic flux density?
Topic: Units of Magnetic Flux Density
Correct Answer: A) NA-1 m-1
- The standard international (S.I) unit for magnetic flux density is the Tesla, represented as NA-1 m-1.
- This unit signifies the directedness of a magnetic field at a certain point in space.
Question 12:
What is the equivalent measurement of one Tesla?
Topic: Equivalence of Tesla
Correct Answer: B) wb.m-2
- One Tesla, the unit of magnetic flux density, is equivalent to wb.m-2.
- This helps in expressing magnetic flux density in different terms while solving problems.
Question 13:
During a constant speed motion of a charge, what is generated?
Topic: Effect of Moving Charge on Magnetic Field
Correct Answer: B) Constant magnetic field
- A charge moving with uniform speed results in the creation of a constant magnetic field around it.
- This means that the strength and direction of the magnetic field remain the same at any given point around the moving charge.
Question 14:
In a galvanometer, what is the current relative to?
Topic: Current in a Galvanometer
Correct Answer: C) The deflection angle of the suspension wire
- The current in a galvanometer is proportional to the angle of deflection of the suspension wire.
- This relationship is shown in the equation I = c θ / BAN, where c/BAN is constant, yielding I ∝ θ.
Question 15:
What is the S.I unit of Magnetic Permeability?
Topic: Units of Magnetic Permeability
Correct Answer: D) Wb/(A.m)
- The SI unit for magnetic permeability is Wb/(A.m).
- In response to a magnetic field, it indicates how much the material is magnetized.
Question 16:
What condition will prevent an electron from deflecting when it enters an electric field "E" perpendicular to magnetic field "B"?
Topic: Charge Particle in Electric and Magnetic Fields
Correct Answer: B) E = vB
- E = vB prevents an electron from deflecting when it enters a region where the magnetic field is perpendicular to the electric field.
- This is because the magnetic force and electric force cancel each other out, resulting in zero net force on the particle, and thus, no deflection.
Question 17:
What characterizes the nature of magnetic force?
Topic: Nature of Magnetic Force
Correct Answer: C) It's a deflection force
- The magnetic force is essentially a deflecting force.
- When a charged particle moves within a magnetic field, its direction of motion changes.
- The magnitude of the motion remains unchanged.
Question 18:
When two conductors carrying currents are placed closely and parallel to each other, how do their magnetic fields interact in the central region?
Topic: Interaction of Magnetic Fields
Correct Answer: D) They can either cancel or strengthen each other
- When two straight current-carrying wires are placed parallel and close to each other, the interaction of their magnetic fields in the middle region depends on the direction of the currents.
- The magnetic fields tend to cancel out if the currents flow in the same direction.
- Conversely, if the currents flow in opposite directions, the magnetic fields strengthen each other, resulting in repulsion.
Question 19:
For which type of path is Ampere's law valid?
Topic: Application of Ampere's Law
Correct Answer: C) Any path
- Ampere's law applies to any path, regardless of shape.
- Based on this law, the electric current passing through a closed loop is related to the integrated magnetic field around it.
- It holds true in all scenarios, regardless of the path's shape or size.
Question 20:
In what way do two wires, positioned parallel to each other and carrying currents in opposing directions, interact?
Topic: Interaction of Parallel Current-carrying Wires
Correct Answer: A) They push each other away
- Current carried in opposite directions by parallel wires repels each other.
- This repulsion occurs due to the interaction of magnetic fields generated by the currents in each wire.
- The magnetic interaction results in a repulsive force between the wires.
Question 21:
Consider two rectangular current-carrying loops lying on the same plane and positioned close to each other as illustrated in the figure. What is the likely outcome of this arrangement?
Topic: Interactions between Current-carrying Loops
Correct Answer: A) They will attract each other
- The sides of the rectangular loops that are closer to each other carry current in the same direction.
- According to the laws of electromagnetism, currents flowing in the same direction attract each other.
- Therefore, the loops will attract each other due to the magnetic fields generated by the currents they carry.
Question 22:
What can give rise to a magnetic field?
Topic: Generation of Magnetic Fields
Correct Answer: C) Both A and B
- Charges can move or electric fields can change, resulting in magnetic fields.
- Both a moving charge (like an electric current) and a changing electric field can cause a magnetic field.
- This understanding is fundamental to electromagnetism.
Question 23:
Suppose an electron and a proton both enter a magnetic field at a right angle with identical momentum. Which statement would be correct?
Topic: Effect of Magnetic Field on Charged Particles
Correct Answer: B) The deflection is equal for both
- Charge, velocity, and mass all affect the deflection of charged particles in a magnetic field.
- An electron and a proton carry the same magnitude of charge but have different masses.
- If they carry the same momentum, their deflection in a magnetic field will be equal.
- Thus, both an electron and a proton will deflect equally when they enter a magnetic field perpendicularly with the same momentum.
Question 24:
Two lengthy parallel wires, identified as wire 1 and wire 2, are noticed to repel each other. What could possibly be the cause?
Topic: Interaction of Parallel Current-Carrying Wires
Correct Answer: B) Both wires are conducting current in opposite directions
- A parallel wire carrying current in opposing directions repels another parallel wire carrying current in the same direction.
- Magnetic fields generated by wire currents interact with each other, generating a repelling force.
- If two long parallel wires repel each other, it indicates that they carry current in opposite directions.
Question 25:
An electron is noted to move at a velocity of 2×102 m/s at a right angle to a magnetic field. What would be the magnitude of the magnetic force acting on it?
Topic: Magnetic Force on a Moving Charge
Correct Answer: C) 6.4×10-17 N
- The magnetic force (F) acting on a moving charge can be calculated using the equation F = evBsinθ.
- Here, e is the charge, v is the speed, B is the magnetic field strength, and θ is the angle between the velocity and the magnetic field.
- Electrons move perpendicular to magnetic fields at 90 degree angles, so sin90o = 1.
- Plugging in the given values, F = (1.6×10-19)(2×102)(2)sin90o = 6.4×10-17 N.
- Therefore, the magnitude of the magnetic force is 6.4×10-17 N.
Question 26:
A spring carries a certain amount of current. What is the impact on the spring?
Topic: Electromagnetic Effects on a Current-Carrying Spring
Correct Answer: B) The spring contracts
- In a conductive spring, each loop behaves like a small current-carrying coil, producing a magnetic field.
- Neighboring loops with currents flowing in the same direction attract each other due to their magnetic fields.
- As a result, the spring contracts when current passes through it.
Question 27:
In a magnetic field, what happens to the kinetic energy of a charged particle?
Topic: Kinetic Energy of a Moving Charged Particle in a Magnetic Field
Correct Answer: A) Stays constant
- The magnetic force on a charged particle is always perpendicular to the direction of its motion.
- This force causes a change in the direction of the particle's velocity without changing its speed.
- Since kinetic energy depends on speed (not direction), the particle's kinetic energy remains constant in the magnetic field.
Question 28:
What would be the angle between the direction of a moving charged particle and the magnetic field when the magnetic force on the particle is half of its maximum value?
Topic: Angle of Deflection of a Moving Charged Particle in a Magnetic Field
Correct Answer: C) 30°
- Moving charged particles are subjected to magnetic forces by F = qvBsinθ.
- q is the charge, v is the speed, B is the magnetic field strength, and θ is the angle between the velocity and the magnetic field.
- The force achieves its maximum value (Fmax) when sinθ = 1 (i.e., θ = 90°).
- For the force to be half its maximum value (Fmax/2), sinθ should be equal to 0.5.
- The angle corresponding to a sine value of 0.5 is 30°, therefore, θ = 30°.
Question 29:
A batch of positively charged particles is launched into a magnetic field. If the direction of the magnetic field aligns with the movement path of these particles, what will be their fate?
Topic: Behaviour of Charged Particles in a Magnetic Field
Correct Answer: D) The velocity of the particles remains unchanged
- If the motion of charged particles and the magnetic field are in the same direction, the angle (θ) between them is 0°.
- The magnetic force (F) is given by the equation F = qvB sin θ.
- Here, sin 0° = 0, which implies that the force exerted on the particles is zero.
- Consequently, the velocity of the particles remains unchanged.
Question 30:
An electron is moving in a straight line from the left side to the right side of a plane in a perpendicularly outward magnetic field. What is the direction of its deflection?
Topic: Deflection of Electron in a Perpendicular Magnetic Field
Correct Answer: C) Upwards
- The direction of the force acting on a moving electron in a magnetic field can be determined using the left-hand rule.
- Align the thumb, forefinger, and middle finger at right angles to each other (forming an open palm).
- In contrast to conventional current, the middle finger should indicate the electron movement (instead of the forefinger, which indicates the magnetic field).
- The thumb will point in the direction of the force.
- Therefore, the electron is deflected upward.
Question 31:
What do we call the magnetic force that acts on a positive unit charge moving perpendicularly to the magnetic field with unit velocity?
Topic: Definition of Magnetic Induction
Correct Answer: D) Magnetic induction
- An electric charge in a magnetic field is subject to the magnetic force (F) represented by F = qvBsinθ.
- In this scenario, the charge (q) is +1, the velocity (v) is 1, and the angle θ is 90°.
- Hence, sin90° = 1.
- Substituting the values into the equation, we get F = 1*1*B*1 = B.
- Therefore, the term is defined as magnetic induction.
Question 32:
Assume an electron is taking the positive x-direction as its path. A uniform electric field, denoted by "E", exists in the x-direction negatively. If a uniform magnetic field of the right magnitude and direction is also present in this region, the electron will experience zero total force. What should be the direction of this magnetic field?
Topic: Electromagnetic Fields on Electron Movement
Correct Answer: B) Into the plane of the page
- To maintain a zero total force on the electron, the magnetic field must counteract the force of the electric field.
- Remember the right-hand rule: the magnetic field should be directed into the plane of the page (option B) to oppose the electric field.
Question 33:
Consider a scenario where an electron is moving towards the north and a magnetic field is directed towards the south. What is the magnetic force on the electron in this case?
Topic: Magnetic Force on Electrons
Correct Answer: A) Zero
- When the motion of the electron is aligned with the magnetic field (i.e., both are parallel), the angle between them is 180°.
- The magnetic force (F) is given by the equation F = qvB sin θ.
- In this case, sin 180° = 0, which implies the force experienced by the electron is zero.
Question 34:
When a charged particle is propelled perpendicular to a uniform magnetic field, it follows a circular path. What factor is the radius of this circular path proportional to?
Topic: Charged Particle in a Magnetic Field
Correct Answer: D) Both B and C
- The radius of the circular path is directly proportional to the velocity of the charged particle.
- The radius is inversely proportional to the magnitude of the magnetic field and the charge of the particle.
- Answer D indicates that the radius is proportional to the inverse of the particle's charge and the inverse of the applied magnetic field.
Question 36:
Which of the following can be measured using an AVO meter?
Topic: Applications of AVO Meter
Correct Answer: D) All of the above
- An AVO meter, also commonly known as a multimeter, is a versatile instrument used in electrical engineering.
- It gets its name from the three quantities it measures: Amperes (A, for current), Volts (V, for voltage), and Ohms (Ω, for resistance).
- Therefore, it can measure all three quantities mentioned in the options.
- Hence, the correct answer is D) All of the above.
Question 37:
What is the relationship between the orientation of a magnet's poles and the Earth's geographical poles?
Topic: Magnetism and Earth's Geography
Correct Answer: D) They have no specific relationship
- The poles of a magnet and the geographic poles of Earth have no inherent relationship.
- Geographic poles lie at the intersections of the Earth's axis of rotation and its surface.
- A magnet's poles refer to the areas where its magnetic force is strongest, unaffected by Earth's geographical orientation.
- Consequently, the correct answer is D) They have no specific relationship.
Question 38:
What is the magnitude of the force experienced by a charge that is moving in a direction that is parallel to the magnetic field?
Topic: Forces on Charged Particles in a Magnetic Field
Correct Answer: C) It's zero
- In a magnetic field, a charged particle's force is calculated using the equation F = q(v x B) or F = qvB sinθ.
- Here, θ is the angle between the motion of the charged particle and the direction of the magnetic field.
- When the particle moves parallel to the magnetic field, θ equals zero, and hence sin θ equals zero.
- Consequently, the force experienced by the particle is zero.
Question 39:
Which of the following relations applies to an electron moving in a circular path with radius r in a steady magnetic field of strength B?
Topic: Charged Particle Movement in a Magnetic Field
Correct Answer: A) The radius r is directly proportional to the mass m
- In magnetic fields, charged particles move in circular paths.
- The radius of this path is influenced by the charge and mass of the particle, the speed of the particle, and the strength of the magnetic field.
- Out of the provided options, the relation r ∝ m stands true. This means that with the increase in the particle's mass, the radius of the circular path increases.
Question 40:
From where does magnetism originate?
Topic: Fundamental Sources of Magnetism
Correct Answer: C) Electron motion
- Magnetism primarily originates from the spin and orbital motion of electrons.
- This spin and orbital motion generate a magnetic dipole moment, creating magnetic fields.
- Although materials like iron and steel can be magnetized, they are not the origin of magnetism.
- Therefore, the correct answer is C) Electron motion.