The Oersted Experiment demonstrates the relationship between electricity and magnetism, showing that a moving charge creates a magnetic field. This experiment was conducted by Danish physicist Hans Christian Oersted in 1820.
OERSTED EXPERIMENT
Oersted arranged an experimental circuit for this experiment. He arranged a straight wire AB that is connected to a battery and a key. He placed a compass needle (a small magnet) near the wire in N-S direction.
%20(1).webp "Oersted Experiment") |
| Oersted Experiment |
Observation
1. There is no deflection in the needle when the electric current is zero.
2. deflection occurs when current flows.
3. If the current increases, the deflection increases.
4. The deflection of the needle reverses direction when the direction of the electric current is reversed.
5. If the current increases in the reverse direction, the deflection of the needle also increases in the reverse direction.
We know that a magnetic needle is deflected only by the external magnetic field.
Conclusion
✯ When an electric current flows through a conducting wire, a magnetic field is produced around it. This is known as the magnetic effect of current.
✯ The direction and strength of the magnetic field depend on the direction of the current.
✯ When an electric current is passed through a conducting wire, a magnetic field is produced around it.
✯ If the current is passed in the conducting wire in the South-North direction then the compass needle gets deflected towards the geographical West of the North pole.
✯ If the current is passed in the conducting wire in the North-South direction then the compass needle gets deflected towards the geographical East of the North Pole.
Important points
✯ Unification of electricity and magnetism was done by James Maxwell in 1864. He realised that light was an electromagnetic wave.
✯ Radio waves were discovered by Heinrich hertz, and produced by J.C. Bose and G. Marconi.
Magnetic Force
Source and Fields
The electric currents and moving charges produce a magnetic field, denoted by `\vec B`. Magnetic field is a vector quantity. It is several basic properties identical to te electric field. It is defined at each point in space.
Principle of Superposition
The magnetic field created by multiple sources is the vector sum of the magnetic fields produced by each individual source.
Magnetic Field
Magnetic field can be defined as the magnetic force acting on a charged particle moving in a magnetic field. If q coulomb charge is moving with a velocity `\vec v` in a magnetic field `\vec B` then the force acting on it in the absence of electric field is given by following formula
`\vec F = q (\vec v \times \vec B)`
`\vec F = q v B \hatn`
Here, `\theta` is the angle between `\vec v` and `\vec B` and `\hatn` is the unit vector along the direction of `\vec F`
Here,
`F = q v B sin\theta`
If `\theta = 90^\circ` then `F_{max} = q v B`
`B = \frac{F_max}{q v}`
If q = 1 C and v = 1 m / s then
then `B = F_{max} `
Thus, If a unit positive charge (q) moves with unit velocity perpendicular to the magnetic field lines, then the magnetic field strength (B) equals the maximum force experienced by the unit charge.
Magnetic field is a vector quantity. SI unit of magnetic field is `\frac{\text{Weber}}{m^2}` which is also called Tesla.
`1 \text{Tesla} = \frac {1 \text {Weber}}{m^2}`
`1 \text{Tesla} = \frac {1 N}{A \times m}`
CGS unit of magnetic field
`\frac{\text {Maxwell}}{cm^2}` or Gause
The relationship between Tesla and Gauses or one tesla is equal to
`1 \text{Tesla} (T) = 10^4 Gauses (G)`
Dimensions of magnetic field `[M^1L^0T^{- 2}A^{-1}]`
Important points
✯ Magnetic field is also known as intensity of magnetic field, magnetic flux density.
✯ Stationary charge only generates an electric field. Where as moving charge generates both an electric field and magnetic field.
✯ Magnetic field similar to the electric field also follows the principle of superposition.
Moving Charge and Magnetism Class 12 MCQs
Q. Who conducted the Orested Experiment?
Q. What did Orested's experiment demonstrate?
Q. In which year was the Oersted Experiment conducted?
Q. What happens to the compass needle when no current flows through the wire in Oersted's experiment?
Q. What occurs when the current flowing through the wire is increased?
Q. What happens to the compass needle when the direction of the electric current is reversed?
Q. What is the conclusion of Oersted's experiment regarding electric current and magnetic fields?
Q. Who unified electricity and magnetism in 1864?
Q. What did James Maxwell realize about light?
Q. Which scientist discovered radio waves?
Q. What is the SI unit of magnetic field?
Q. How is the magnetic field strength (B) related to the force (F) experienced by a unit positive charge (q) moving with velocity (v)?
Q. The angle between the velocity vector and the magnetic field vector is `90^\circ`, what is the formula for the magnetic force (F)?
Q. What is the CGS unit of magnetic field?
Q. Which statement is true about stationary and moving charges?
No comments:
Post a Comment