Here are some important Electromagnetism topic wise MCQs with answers and explanation for sppu university exams 2020. This contains first 3 topics from sppu syllabus of Electromangnetism Magnetic Field, Direction of magnetic field, Magnetic field due to an electric current.
Magnetic Field
1. What is the magnetic field outside a solenoid?
a) Infinity
b) Half the value of the field inside
c) Double the value of the field inside
d) Zero
Answer: d
Explanation: There are no magnetic lines of force outside a solenoid, hence the magnetic field outside a solenoid is zero.
2. Which, among the following qualities, is not affected by the magnetic field?
a) Moving charge
b) Change in magnetic flux
c) Current flowing in conductor
d) Stationary charge
Answer: d
Explanation: A stationary charge is not affected by a magnetic field because stationary charges do not have any velocity. Magnetic field cannot occur in a particle having zero velocity.
3. When a charged particle moves at right angles to the magnetic field, the variable quantity is?
a) Momentum
b) Speed
c) Energy
d) Moment of inertia
Answer: a
Explanation: When a charged particle moves perpendicular to the field, its speed remains the same whereas its velocity keeps on changing. Momentum is the product of the mass of the particle and the velocity if the particle, hence since velocity varies, momentum also varies.
4. If the flow of electric current is parallel to the magnetic field, the force will be ______
a) Zero
b) Infinity
c) Maximum
d) Half the original value
Answer: a
Explanation: Force is a cross product. A cross product involves the sine of the angle between them. If two quantities are parallel to each other, the angle between them is zero. Sin(0) is zero, hence force is zero.
5. The ratio of magnetic force to electric force on a charged particle getting undeflected in a field is?
a) 1
b) 0
c) 2
d) 4
Answer: a
Explanation: When a charged particle is undeflected in a field, the magnitude of the magnetic force and electric force acting on the particle is the same, hence the ratio is 1.
6. What is the strength of magnetic field known as ________
a) Flux
b) Density
c) Magnetic strength
d) Magnetic flux density
Answer: d
Explanation: Strength of magnetic filed is also known as magnetic flux density. It is the amount of magnetic flux lines crossing through unit area.
7. Weakest force in nature is?
a) Electric force
b) Gravitational force
c) Weak force
d) Magnetic force
Answer: a
Explanation: Gravitational force is the weakest force in nature as it does not bind anything strongly with its help.
8. How can a magnetic field be produced?
a) Using a permanent magnet
b) Electric current
c) Using a temporary magnet
d) Using a permanent magnet or electric current
Answer: d
Explanation: An electric filed as well as a permanent magnet produces a magnetic field whereas a temporary magnets fails to do so.
9. Can we see magnetic flux lines?
a) Yes b) No
c) Depends on the strength of the field
d) Only when field strength is very large
Answer: b
Explanation: No, we cannot see magnetic flux lines as the “lines of magnetic flux” is purely an imaginary concept to understand the magnetic field clearly.
10. Magnetic Field lines move from _______
a) North to south
b) South to north
c) West to east
d) East to west
Answer: a
Explanation: Magnetic field lines originate at the north pole and terminate at the south pole of the magnet.
“Direction of Magnetic Field”.
1. Field lines move from __________
a) North to south
b) South to north
c) West to east
d) East to west
Answer: a
Explanation: Magnetic field lines originate at the north pole and terminate at the south pole of the magnet.
2. Magnetic field lines ___________ at the North Pole.
a) Emerge
b) Converge
c) Neither emerge nor converge
d) Either emerge or converge
Answer: a
Explanation: Magnetic field lines emerge at the north pole. Field lines seem to emerge at the north pole because they originate at the north pole.
3. Magnetic field lines ___________ at the south pole.
a) Emerge
b) Converge
c) Neither emerge nor converge
d) Either emerge or converge
Answer: b
Explanation: Magnetic field lines converge at the south pole. Field lines seem to converge at the south pole because they end at the south pole.
4. Which of the following is used to determine the direction of magnetic field in a current carrying conductor?
a) Left hand thumb rule
b) Right hand thumb rule
c) Right hand palm rule
d) Left hand palm rule
Answer: b
Explanation: The right hand thumb rule determines the direction of magnetic field in a current carrying conductor. The rule states that when we align our right thumb in the direction of the current and curl our fingers around it, the direction of our fingers is the direction of the magnetic field.
5. According to Flemming’s left hand rule, the index finger denotes?
a) Direction of magnetic field
b) Direction of current
c) Direction of force
d) Direction of force as well as current
Answer: a
Explanation: According to Flemming’s left hand rule, the index finger denotes the direction of magnetic field, the thumb denoted the direction of force and the middle finger denoted the direction of current.
6. According to Flemming’s left hand rule, the middle finger denotes?
a) Direction of magnetic field
b) Direction of current
c) Direction of force
d) Direction of force as well as current
Answer: b
Explanation: According to Flemming’s left hand rule, the index finger denotes the direction of magnetic field, the thumb denoted the direction of force and the middle finger denoted the direction of current.
7. According to Flemming’s left hand rule, the thumb denotes?
a) Direction of magnetic field
b) Direction of current
c) Direction of force
d) Direction of force as well as current
Answer: c
Explanation: According to Flemming’s left hand rule, the index finger denotes the direction of magnetic field, the thumb denoted the direction of force and the middle finger denoted the direction of current.
8. The relation between the direction of force and the direction of magnetic field is _________
a) Same direction
b) Opposite direction
c) Perpendicular
d) Unrelated
Answer: c
Explanation: When a conductor carries a certain value of current, the force developed in the conductor, the current in the conductor and the magnetic field in the conductor are mutually perpendicular to each other.
9. The relation between the direction of current and the direction of magnetic field is ________
a) Same direction
b) Opposite direction
c) Perpendicular
d) Unrelated
Answer: c
Explanation: When a conductor carries a certain value of current, the force developed in the conductor, the current in the conductor and the magnetic field in the conductor are mutually perpendicular to each other.
10. The relation between the direction of current and the direction of force is _________
a) Same direction
b) Opposite direction
c) Perpendicular
d) Unrelated
Answer: c
Explanation: When a conductor carries a certain value of current, the force developed in the conductor, the current in the conductor and the magnetic field in the conductor are mutually perpendicular to each other.
“Magnetic Field Due to an Electric Current”
1. If the flow of electric current is parallel to the magnetic field, the force will be ______
a) Zero
b) Infinity
c) Maximum
d) Half the original value
Answer: a
Explanation: Force is a cross product. A cross product involves the sine of the angle between them. If two quantities are parallel to each other, the angle between them is zero. Sin(0) is zero, hence force is zero.
2. The force existing between two infinite parallel conductors is inversely proportional to ________
a) Radius of the conductors
b) Current in one of the conductors
c) The product of the current in the two conductors
d) The distance between the two conductors
Answer: d
Explanation: When current is flowing in two different conductors, the force between the two conductors is directly proportional to the product of the current in the two conductors and inversely proportional to the distance between the two conductors.
3. When the distance of operation between the two conductors increases, what happens to the force between the two conductors?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero
Answer: b
Explanation: When the distance of separation increases, the force between the two conductors decrease because force between two conductors is inversely proportional to the distance of separation between them.
4. Which of the following is used to determine the direction of magnetic field in a current carrying conductor?
a) Left hand thumb rule
b) Right hand thumb rule
c) Right hand palm rule
d) Left hand palm rule
Answer: b
Explanation: The right hand thumb rule determines the direction of magnetic field in a current carrying conductor. The rule states that when we align our right thumb in the direction of the current and curl our fingers around it, the direction of our fingers is the direction of the magnetic field.
5. According to Flemming’s left hand rule, the index finger denotes ________
a) Direction of magnetic field
b) Direction of current
c) Direction of force
d) Direction of force as well as current
Answer: a
Explanation: According to Flemming’s left hand rule, the index finger denotes the direction of magnetic field, the thumb denoted the direction of force and the middle finger denoted the direction of current.
6. According to Flemming’s left hand rule, the middle finger denotes _________
a) Direction of magnetic field
b) Direction of current
c) Direction of force
d) Direction of force as well as current
Answer: b
Explanation: According to Flemming’s left hand rule, the index finger denotes the direction of magnetic field, the thumb denoted the direction of force and the middle finger denoted the direction of current.
7. According to Flemming’s left hand rule, the thumb denotes _________
a) Direction of magnetic field
b) Direction of current
c) Direction of force
d) Direction of force as well as current
Answer: c
Explanation: According to Flemming’s left hand rule, the index finger denotes the direction of magnetic field, the thumb denoted the direction of force and the middle finger denoted the direction of current.
8. The relation between the direction of force and the direction of magnetic field in a current carrying conductor is?
a) Same direction
b) Opposite direction
c) Perpendicular
d) Unrelated
Answer: c
Explanation: When a conductor carries a certain value of current, the force developed in the conductor, the current in the conductor and the magnetic field in the conductor are mutually perpendicular to each other.
9. The relation between the direction of current and the direction of magnetic field in a current carrying conductor is?
a) Same direction
b) Opposite direction
c) Perpendicular
d) Unrelated
Answer: c
Explanation: When a conductor carries a certain value of current, the force developed in the conductor, the current in the conductor and the magnetic field in the conductor are mutually perpendicular to each other.
10. The relation between the direction of current and the direction of force in a current carrying conductor is?
a) Same direction
b) Opposite direction
c) Perpendicular
d) Unrelated
Answer: c
Explanation: When a conductor carries a certain value of current, the force developed in the conductor, the current in the conductor and the magnetic field in the conductor are mutually perpendicular to each other.
