# Assignment for short answer type questions of electromagnetic induction and alternating current

## this Assignment for short answer type questions of electromagnetic induction and alternating current contain all short type questions which is important for board examination of class 12th

Q1. In a series LCR circuit, obtain the conditions under which (i)the impedance of the circuit is minimum and  (ii)wattles current flows in the circuit.

Q2. what is the power dissipated by an ideal inductor in AC circuit? Explain.

Q3. When an AC source is connected to an ideal capacitor, show that the average power supplied by the source over a complete cycle is zero.

Q4. Prove that the power dissipated in an ideal resistor connected to an AC source is Veff 2   / R.

Q5. State the principle of working of a transformer. Can a transformer be used to step up or step down a d.c. voltage ? Justify your answer.

Q6. State the underlying principle of a transformer. How is the large scale transmission of electric energy over long distances done with the use of transformers?

Q7. Define power factor. State the conditions under which it is  (i)maximum (ii) minimum.

Q8. Show that the current leads the voltage in phase by n/2 in an AC circuit containing an ideal capacitor.

Q9. State Lenz’s law.

A metallic rod held horizontally along east- west direction, is allowed to fall under gravity. Will there be an emf induced at its ends? Justify your answer.

Q10. show that Lenz’s law is in accordance with the law of conservation of energy.

Q11. In an experimental arrangement of two coils C1 and C2 placed coaxially parallel to each other, find out the expression for the emf induced in the coil C1 (of N1 turns) corresponding to the change of current I2 in the coil C2 (of N2 turns).

Q12. (a)How does the mutual inductance of a pair of coils change when

(i)distance between the coils increased and

(ii)number of  turns in the coil increased

(b) A plot of magnetic flux (ɸ) versus current (I), is shown in the figure for two inductors A and B. which one the two has large value of self inductance?

(c)How is the mutual inductance of a pair of coils effected when

(i)separation between the coils increased

(ii)the number of turns in each coil is increased

(iii)a thin iron sheet is placed between the two coils, other factors remaining the same ?

Q13. Define self-inductance of a coil . show that magnetic energy required to build up the current I in a coil of a self inductance L. is given by½ LI2. .

OR

Define the term self- inductance of a solenoid. Obtain the expression for the magnetic energy stored in an inductor of self- inductance L. to build up a current I through it.