In the relation \(\phi \) = BA cos \(\theta \), \(\theta \) is angle........

Out of the following, choose the correct relation

Phase difference between voltage across L and C in series is

The relation \(\frac { { E }_{ s } }{ { E }_{ p } } =\frac { { n }_{ s } }{ { n }_{ p } } \) is applied only to

An e.m.f. is produced in a coil, which is not connected to an external voltage source. This can be due to 

Show that the rate of change of magnetic flux has the same units as induced e.m.f.

A circular brass loop of radius a and resistance R is placed with its plane perpendicular to a magnetic field, which varies with time as \(B={ B }_{ 0 }sin\omega t.\) Obtain the expression for the induced current in the loop.

A solenoid with an iron core and a bulb are connected to a d.c. source. How does the brightness of the bulb change when iron core is removed from the solenoid?

In India, domestic power supply is at 220 V, 50 hz, while in U.S.A, it is 110 V, 60 hz. Give one advantage and one disadvantages of 220 V supply over 110 V supply.

Can a.c. source be connected to a circuit and yet deliver no power to it? If so, under what circumstances?

(a) Obtain an expression for the mutual inductance between a long straight wire and a square loop of a side a as shown inthe figure given below.

(b) Now assume that the straight wire carries a current of 50 A and the loop is moved to the right with constant velocity, V=10ms^-1. Calculate the induced emf in the loop at the instant when x=0.2m. Take a=0.1 m and assume that the loop has a large resistance.

A series LCR circuit with \(R=20\Omega \) , L=1.5H and \(C=35\mu F\) is connected to a variable frequency 200 V ac supply. When the frequency of the supply equals the natural frequency of the circuit, what is the average power transferred to the circuit in one complete cycle?

A square loop of side 12 cm with its sides parallel to x and y axes is moved with a velocity of 8 cm \({ s }^{ -1 }\) in the positive x-direction in an environment containing a magnetic field in the positive z direction. The field is neither uniform in space nor constant in time. It has a gradient of \({ 10 }^{ -3 }T\quad { cm }^{ -1 }\) along the negative x-direction (i.e. it increases by \({ 10 }^{ -3 }T\quad { cm }^{ -1 }\) as one moves in the -ve x direction), and it is decreasing in time at the rate of \({ 10 }^{ -3 }T\quad { cm }^{ -1 }\). Determine the direction and magnitude of the induced current in the loop if its resistance is 4.5 m \(\Omega \)

An air cored solenoid with length 30cm, area of cross-section 25cm² and number of turns 500 carries a current of 2.5A. The current is suddenly switched off in a brief time of 10^-3s. How much is the average back e.m.f. induced across the ends of the open switched in the circuit? Ignore the variation in magnetic field near the ends of the solenoid.

A 100 resistor is connected to a 220V, 50Hz ac supply.
(a) What is the rms value of current in the circuit?
(b) What is the net power consumed over a full cycle?

Draw a labelled diagram of a step-down transformer. State the principle of its working.
Express the turn ratio in terms of voltages.
Find the ratio of primary and secondary currents in terms of turn ratio in an ideal transformer.
How much current is drawn by the primary of a transformer Connected to 220 V supply when it delivers power to a 110 V-550 W refrigerator?

Raj who is in class XII was demonstrated with an experiment of Faraday's laws of electromagnetic induction by his Physics teacher. While his teacher was explaining the experiment, her lecture and raised a question that "Is there any possibility of induced emf due to earth's magnetism"? After listening his question, the Physics teacher was stunned for a moment and without giving answer, discusses this question in group discussion. In the group discussion, students came out with correct answer.
(i) Write the values that you learnt from this incident.
(ii) What can be the reason for Rays questions?

A square loop of side 10cm and resistance 0.70ohm is placed vertically in the east-west plane. A uniform magnetic field of 0.10T is set up across the plane in north-east direction. The magnetic field is decreased to zero in 0.7 sec. at a steady rate. Determine the magnitudes of induced e.m.f. and current during this time interval.

Magnetic field of 2\(\times\)10^-2 Wb m^-2 is acting at right angle to a coil of 1000 cm having 50 turns. The coil is removed from the field in \(\frac { 1 }{ 10 } \)second. Find the magnitude of induced e.m.f.