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Magnetic force is the attraction or repulsion force that results from the motion of electrically charged particles. The magnets are attracted or repellent to one another due to this force. A compass, a motor, the magnets that hold the refrigerator door, train tracks, and modern roller coasters are all examples of magnetic power. A magnetic field is generated by all moving charges, and the charges that pass through its regions feel a force. Depending on whether the force is attractive or repulsive, it may be positive or negative. The magnetism force is determined by the object's charge, velocity, and magnetic field.
Read More: Magnetic Field due to current element
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Key Takeaways: Magnetic Field, Magnetic Force, Fleming’s Right Hand Rule, Current Carrying Conductor, Charge, Magnetism, Velocity, Magnets
Force Applied To a Moving Charge
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A charge will feel a force as it passes through a magnetic field at an angle. This force is given by the equation:
F = qvB sinθ
where,
q is the charge
B is the magnetic field
v is the velocity
θ is the angle between the magnetic field and velocity directions.
A force acts on the motion of charge q travelling with velocity v in a Magnetism field, and this force is:
- Perpendicular to both v and B.
- Perpendicular to sinθ (where θ is the angle between v and B).
- Proportional to the charge q.
- Proportional to the velocity v.
Also Read:
Fleming's Right Hand Rule
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- The Right-hand rule may be used to determine the force's trajectory (F).
- It refers to devices that produce currents by moving in a magnetic field.
- Place your index finger along the charge v direction of motion.
- Between v and B, rotate your middle finger away from your index finger.
- Maintain a perpendicular relationship between your thumb and the plane created by your index and middle fingers.
- If the charge q is positive, your thumb will point in the direction of the force (F).
Read More: NCERT Solutions Chapter 4 Moving Charges and Magnetism
Magnetic Field
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Magnetic field is an unseen field of attractive force that surrounds a magnet. It is a term that describes how magnetic force is distributed around a magnetic object. When an electric charge/current moves in the vicinity of a magnet, magnetic fields are formed or generated. A magnetic field is generated when a subatomic particle with a negative charge, such as electrons, travels around. Magnetic objects' atoms, as well as electrical conductors and wires, can generate these fields.
Magnetic Field Representation
The magnetic field can be represented in a variety of ways. It can be interpreted mathematically as a vector field that can be plotted as different sets on a grid. The use of field lines is another choice. Lines are used to link the set of vectors. The magnetic field lines never cross and never come to a halt here.
Magnetic Field Measurement and Unit
Magnetic field is measured by determining its intensity and direction. The magnetic field strength varies from small and weak to very strong and high. When we look at the earth's magnetic field, we can see that it is small but strong. Despite this, the term magnetic field refers to two distinct but connected fields, typically denoted by the letters H and B. H stands for magnetic field strength and is measured in ampere per meter (SI unit). B, on the other hand, stands for magnetic flux density and is measured in tesla.
Read More: Important Formula in Electricity
Magnetic Field Sue to Current Carrying Conductor
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When an electrical charge moves, a magnetic field is formed. Consider a wire that is connected to a battery and through which the current is forced to flow. The magnetic field rises concerning the current flowing through the conductor. The magnetic field decreases with distance as we travel farther away from the wire. Ampere's law describes this phenomenon. The magnetic field at a distance r from a long current-carrying conductor I, according to the law, is given by the equation
B=μ0I2πr
Where, μ0 is a special constant defined as the permeability of free space in the equation. μ0=4π×10−7T⋅m/A
Magnetic fields can be concentrated by materials with higher permeability. Since it is a vector quantity, the magnetic field has direction. Fleming’s right-hand rule can be used to calculate the traditional current flowing through a straight cable. To apply this law, imagine wrapping your right hand around the wire and pointing your thumb in the current's direction. The orientation of the magnetic field that wraps around the wire is indicated by the fingertips.
Read More: Magnetic Spectrum
Things to Remember
- Magnetic force is the attraction or repulsion force that results from the motion of electrically charged particles.
- Fleming’s Right-hand rule may be used to determine the magnetic force's trajectory (F).
- Magnetic field is an unseen field of attractive force that surrounds a magnet.
- When an electrical charge moves, a magnetic field is formed.
- Magnetic field due to a current carrying conductor is given by the equation, B=μ0I2πr.
Read More:
Previous Year Questions
- An electron in motion is associated with… [ KCET 1996]
- Two parallel wires carry electric current in same direction. The wires... [ KCET 1996]
- Resistance of an ideal ammeter is...[ KCET 1996]
- If a current of 0.1 A is passed through the coil, what is the couple acting?...[CBSE Class 12 ]
- The acceleration of the falling magnet is..[NEET]
- A bar magnet is equivalent to ............[KCET 2004]
- A metal ring is held horizontally and bar magnet is dropped through….[NEET]
- The total charge, induced in a conducting loop when it is moved in magnetic field depend on...[NEET 1992]
- If a charge particle enters perpendicular in the uniform magnetic field, then...[JIPMER 2016]
- Who invented the cyclotron?
- When a charged particle moving with velocity is….
- The angle of dip at a place is….
- The associated magnetic moment is given by….
- A uniform electric field and a uniform magnetic field are produced…
- Ampere’s circuital law can be derived from…..
- If a magnetic dipole of moment M situated in the direction of …
- If the susceptibility of dia, para and ferro magnetic materials are ….
- Materials suitable for permanent magnet, must have which of the following properties ?
- At what temperature, the ferromagnetic substances become paramagnetic ?
- a magnetic induction of strength at its centre is...
Sample Questions
Ques. How can you calculate the magnetic force of 50 C charged particles traveling at 3m/s in a 1T magnetic field? Its field has the same direction as the second particle's path. (2 marks)
Ans. q=50C, v=3m/s, and B=1T are the given parameters.
Since the second particle's path difference is the same as its field's direction, θ=0°
F= q v B sin θ = 50x3x1x sin θ =0 is the magnitude force formula.
Ques. What is the source of the Earth's magnetic field? (2 marks)
Ans. The magnetic field of the Earth is created deep inside its nucleus. The movement of liquid iron at the Earth's center creates an electric current, which causes magnetic fields to form. Charged metals going through these fields generate their electric currents, continuing the loop. The geodynamo is the name for this self-sustaining loop. Separate magnetic fields are aligned in the same direction due to the spiraling generated by the Coriolis force. The combined effect of magnetic fields creates a massive magnetic field that encompasses the entire earth.
Ques. Define the strength of the magnetic field. (2 marks)
Ans. The Magnetic Field Intensity (MFI) or Magnetic Field Strength (MFS) is a ratio of the MMF needed to produce a certain Flux Density (B) within a material per unit length of that material.
Ques. What is the significance of magnetic flux lines? (3 marks)
Ans. Magnetic flux lines are important for a variety of reasons:
Magnetic field lines are the lines in a magnetic field whose tangent gives the field direction at any given point and whose density gives the field magnitude.
They indicate the magnetic field's path.
The number of magnetic field lines determines the strength of the magnetic field. Since the lines are longer at the poles, the magnetic field is stronger there.
The strength of a magnetic field is proportional to the number of magnetic field lines present in a given area.
Ques. What are electromagnetic waves, and how do they work? (2 marks)
Ans. Electromagnetic waves are waves that propagate as a result of simultaneous periodic changes in electric and magnetic field strength.
Ques. Is it true that there are magnetic fields in space? (2 marks)
Ans. Magnetic fields exist in space, indeed. Based on measurements of a large number of pulsars and the polarisation of their radio signals, the spiral arms of the Milky Way seem to have some very large-scale coordinated magnetic field. Magnetic fields have been discovered in interstellar dust clouds. The fields are intensified as the clouds fall.
Ques. Define the density of magnetic flux. (2 marks)
Ans. The sum of magnetic flux in an area measured perpendicular to the magnetic flux's path is known as magnetic flux density. It is denoted by the letter B and is represented in Tesla units.
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