Previous Year Questions

## Electromagnetic Induction

- Practice Previous Year questions to get a better idea of the CBSE exam.
1
Calculate the induced emf in a closed loop.
(a) State the principle of an ac generator and explain its working with the help of a labelled diagram. Obtain the expression for the emf induced in a coil having turns each of cross-sectional area , rotating with a constant angular speed in a magnetic field , directed perpendicular to the axis of rotation.
(b) An aeroplane is flying horizontally from west to east with a velocity of . Calculate the potential difference developed between the ends of its wings having a span of . The horizontal component of the Earth's magnetic field is and the angle of dip is .
2
Basics problems on gauss law, faraday law and Lenz's law.
Answer the following :
A metallic rod of length is rotated with an angular velocity about an axis passing through its mid-point (O) and perpendicular to the plane of the paper, in uniform magnetic field , as shown in the figure. What is thee potential difference developed between the two ends of the rod, P and Q ?
A bar magnet is moved in the direction indicated by the arrow between two coils PQ and CD. Predict the direction of the induced current in each coil.
3
Solve problems on inductor circuits with varying inductance.
Draw the graph showing variation of the value of the induced emf as a function of rate of change of current flowing through an ideal inductor.
4
Problems On Self And Mutual Inductance
Define mutual inductance between a pair of coils. Derive an expression for the mutual inductance of two long coaxial solenoids of same length wound one over the other.
Define self-inductance of a coil. Obtain the expression for the energy stored in an inductor L connected across a source of emf.
5
Use the relationship between line integral of electric field and surface integral of magnetic field.
Find the condition under which the charged particles moving with different speeds in the presence of electric and magnetic field vectors can be used to select charged particles of a particular speed.
6
Describe the applications and disadvantages of eddy currents.
(a) How are eddy currently generated in a conductor which is subjected to n magnetic field?
(b) Write two examples of their useful applications.
(c) How can the disadvantages of eddy currents be minimized?
7
Calculate the emf induced in an AC generator.
Draw a labelled diagram of an ac generator. Obtain the expression for the emf induced in the rotating coil of N turns each of cross-sectional area A, in the presence of a magnetic field .