Question
What is self induction ? Obtain expression for self induced emf.
✓
Answer
→When electric current through an isolated conducting coil is changed, magnetic flux linked with it changes. As a result, induced emf is produced in the coil. This phenomenon is called self induction.
→Here, induced emf is called self induced emf.
→Suppose, electric current passing through an isolated coil having N turns is I .
→Total magnetic flux linked with coil,
$\begin{array}{c}
N \phi_{ B } \propto I \\
\therefore \quad N \phi_{ B }= L I
\end{array}$
→Proportionality constant L in equation (1) is called self inductance.
→On changing current with time, magnetic flux linked changes. As a result, induced emf is produced.
$\therefore N \frac{d \phi_{ B }}{d t}= L \frac{d I }{d t}$
→According to Faraday's law,
$\varepsilon=- N \frac{d \phi_{ B }}{d t}$
From equation (2) and (3),
$\varepsilon=- L \frac{d I }{d t}$
Equation (4) is expression for self induced emf.
→Here, induced emf is called self induced emf.
→Suppose, electric current passing through an isolated coil having N turns is I .
→Total magnetic flux linked with coil,
$\begin{array}{c}
N \phi_{ B } \propto I \\
\therefore \quad N \phi_{ B }= L I
\end{array}$
→Proportionality constant L in equation (1) is called self inductance.
→On changing current with time, magnetic flux linked changes. As a result, induced emf is produced.
$\therefore N \frac{d \phi_{ B }}{d t}= L \frac{d I }{d t}$
→According to Faraday's law,
$\varepsilon=- N \frac{d \phi_{ B }}{d t}$
From equation (2) and (3),
$\varepsilon=- L \frac{d I }{d t}$
Equation (4) is expression for self induced emf.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Is work-energy theorem valid in non-inertial frames?
In a potentiometer arrangement for determining the emf of a cell, the balance point of the cell in open circuit is 350cm. When a resistance of $9\Omega$ is used in the external circuit of the cell, the balance point shifts to 300cm. Determine the internal resistance of the cell.
→The distance between the cathode (filament) and the target in an X-ray tube is 1.5m. If the cutoff wavelength is 30pm, find the electric field between the cathode and the target.
In an electrolyte, the positive ions move from left to right and the negative ions from right to left. Is there a net current? If yes, in what direction?
Current is allowed to flow in a metallic wire at a constant potential difference. When the wire becomes hot, cold water is poured on half of its portion. By doing so, its other half portion becomes still more hot. Explain its reason.
Why is the luminous efficiency small for a filament bulb as compared to a mercury vapour lamp?
Write the definition of wave front.
Define two magnetic elements of the earth.
Figure shows a conducting circular loop of radius a placed in a uniform, perpendicular magnetic field B. A thick metal rod OA is pivoted at the centre O. The other end of the rod touches the loop at A. The centre O and a fixed point C on the loop are connected by a wire OC of resistance R. A force is applied at the middle point of the rod OA perpendicularly, so that the rod rotates clockwise at a uniform angular velocity $\omega.$ Find the force.
→An extended object is placed at a distance of 5.0cm from a convex lens of focal length 8.0cm.
- Draw the ray diagram (to the scale) to locate the image and from this, measure the distance of the image from the lens.
- Find the position of the image from the lens formula and see how close the drawing is to the correct result.