CBSE Class 12 Physics EMI and AC Assignment

EMI And AC MCQ Questions with Answers Class 12 Physics

More question-

Q1- Two identical loops,one of copper and another of constanton,are removed from a magnetic field within the same time interval.In which loop the induced current will be greater?

Q2- 

B In the wire AB current is decreasing.What is the directrion of induced Current in the square loop?

Q3- Define the term self inductance. Write its SI unit.

Q4- Find the capacitance of the capacitor that would have the reactance of 100ohm when used with an ac source of frequency5/π KHZ.

Q5- Current and voltage in the circuit are I=10 Sin 314t and V=50 Sin (314t + π/2)V. What is the power dissipation in the circuit?

Q6- A conducting rod of length l,with one end pivoted, is rotated with a uniform angular speed w in a vertical plane, normal to the uniform magnetic field B. Deduce an expression for the emf induced in this rod.

Q7.- 

(A) Find the induced current in the circuit. R L V (B) Find the minimum force required for pulling the Sliding arm with constant speed v.

Q8. An electric heater is connected ,turn by turn, to a dc and ac sources of equal voltages. Will the rate of heat production be same in two cases? Explain.

Q9- Prove that in a series LCR circuit, the power dissipated depends not only on the voltage and current but also on the cosine of the phase angle Φ between these two

Q10- Prove that on applying an ac across an inductor voltage leads to current by phase π/2 radian.

Q11. An alternating voltage of frequency f is applied across a series LCR circuit.Let fr be the resonance frequency.Will the current in the circuit lag,lead or remain in phase with the applied voltage when (a)f>fr (b) f < fr Explain your answer in each case.

Q12.(A) Plot a graph showing variation of current with frequency of ac source in a series LCR
circuit.(B)Plot a graph showing the variation of impedence of a series LCR circuit with the
frequency of applied ac source.

Q13.When a series combination of L and R are connected with a 10v,50hz,ac source, a current of
1amp flows in the circuit. The voltage leads the current by a phase angle of π/3 radian. Calculate
the value of L and R.

Q14.Write the principle of transformer. Prove that in a step up transformer current decreases
across the secondary .Why we transmit the power at high voltage?

Q15-Write the principle and working of ac generator.

Q16-(A) Derive an expression for self inductance of a coil.
(B)There are two concentric loop of radius r and R (r<<R).Derive an expression for mutual
inductance of the coils. (2)