Why induced EMF is called back EMF?

Content Curator

The term "back EMF" is used in relation to the phenomenon of electromagnetic induction. When a magnetic field is changed, it produces an electromotive force (EMF) across a conductor placed within the field. This induced EMF is in opposition to the change in the magnetic field that is producing it, and therefore it is called "back EMF."

For example, when a coil of wire is placed within a magnetic field and the magnetic field is varied, it induces an EMF in the coil. If the magnetic field is increasing, the induced EMF will be in the opposite direction of the magnetic field, acting as a brake. This is because the induced current produced by the EMF produces its own magnetic field, which opposes the original field.

In other words, the induced EMF acts as a "backwards" force, resisting the change in magnetic field that is producing it. This is why it is called "back EMF." It is important to note that the direction of the induced EMF is always such that it opposes the change that is causing it, following Lenz's Law.

Back EMF

Back EMF

Also check:

Important Topics from EMF
EMF MCQs	Electrical Current	Types of Current
EMF Important Questions	Electrical Resistance	Cells In Series and Parallel
Relation between Resistance and Length	Potentiometer	Meter Bridge
Wheatstone Bridge	Kirchhoff’s Rules	Potentiometer

CBSE CLASS XII Related Questions

1.
A wire of length $L$ is bent round into (i) a square coil having $N$ turns and (ii) a circular coil having $N$ turns. The coil in both cases is free to turn about a vertical axis coinciding with the plane of the coil, in a uniform, horizontal magnetic field and carry the same currents. Find the ratio of the maximum value of the torque acting on the square coil to that on the circular coil.

View Solution

2.
The resistance of a metal wire at $20^\circ\text{C}$ is $1.05\,\Omega$ and at $100^\circ\text{C}$ is $1.38\,\Omega$. Determine the temperature coefficient of resistivity of this metal.

View Solution

3.
In a region, the electric potential varies as $V = 10 - 50x$, where $V$ is in volts and $x$ is in meters. The electric field in the region is

$10\ \text{N/C}$ along $+x$
$10\ \text{N/C}$ along $-x$
$50\ \text{N/C}$ along $+x$
$50\ \text{N/C}$ along $-x$

View Solution

4.
Consider a cylindrical conductor of length $l$ and area of cross-section $A$. Current $I$ is maintained in the conductor and electrons drift with velocity $\vec{v}_d$ ($|\vec{v}_d| = \frac{e|\vec{E}|}{m}\tau$), (where symbols have their usual meanings). Show that the conductivity $\sigma$ of the material of the conductor is given by
$$\sigma = \frac{ne^2}{m}\tau.$$

View Solution

5.
A circular coil of 100 turns and radius $\left(\frac{10}{\sqrt{\pi}}\right)$ cm carrying current of $5.0\,\text{A}$ is suspended vertically in a uniform horizontal magnetic field of $2.0\,\text{T}$. The field makes an angle $30^\circ$ with the normal to the coil. Calculate:
(I) the magnetic dipole moment of the coil, and
(II) the magnitude of the counter torque that must be applied to prevent the coil from turning.

View Solution

6.
Consider the nuclear reaction $ X \to Y + Z $. Let $ M_x $, $ M_y $, and $ M_z $ be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?

$ (M_x - M_z)<M_y $
$ (M_x - M_y)<M_z $
$ M_x>(M_y + M_z) $
$ M_x<(M_y + M_z) $

View Solution

Why induced EMF is called back EMF?

CBSE CLASS XII Related Questions

2.
The resistance of a metal wire at \(20^\circ\text{C}\) is \(1.05\,\Omega\) and at \(100^\circ\text{C}\) is \(1.38\,\Omega\). Determine the temperature coefficient of resistivity of this metal.

3.
In a region, the electric potential varies as \(V = 10 - 50x\), where \(V\) is in volts and \(x\) is in meters. The electric field in the region is

6.
Consider the nuclear reaction \( X \to Y + Z \). Let \( M_x \), \( M_y \), and \( M_z \) be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?

Similar Physics Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

Why induced EMF is called back EMF?

CBSE CLASS XII Related Questions

2.The resistance of a metal wire at \(20^\circ\text{C}\) is \(1.05\,\Omega\) and at \(100^\circ\text{C}\) is \(1.38\,\Omega\). Determine the temperature coefficient of resistivity of this metal.

3.In a region, the electric potential varies as \(V = 10 - 50x\), where \(V\) is in volts and \(x\) is in meters. The electric field in the region is

6.Consider the nuclear reaction \( X \to Y + Z \). Let \( M_x \), \( M_y \), and \( M_z \) be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?

Similar Physics Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

2.
The resistance of a metal wire at \(20^\circ\text{C}\) is \(1.05\,\Omega\) and at \(100^\circ\text{C}\) is \(1.38\,\Omega\). Determine the temperature coefficient of resistivity of this metal.

3.
In a region, the electric potential varies as \(V = 10 - 50x\), where \(V\) is in volts and \(x\) is in meters. The electric field in the region is

6.
Consider the nuclear reaction \( X \to Y + Z \). Let \( M_x \), \( M_y \), and \( M_z \) be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?