Recent questions in Electromagnetic induction

The dimensions of electric and magnetic flux are same. Say true or false.

asked Dec 30, 2016 by suganyadevi.p

1 answer

A coil of a metal wire is kept stationary in a non - uniform magnetic field. An emf is induced in the coil. Say true or false.

asked Dec 30, 2016 by suganyadevi.p

1 answer

A magnetic field of 10T acts normal to a coil of 50 turns having $100 cm^2$ area. Find emf induced if the coil is removed from magnetic field in 0.1 sec.

asked Dec 30, 2016 by suganyadevi.p

1 answer

A circular copper disc 10 cm in radius rotates at $20\pi$ rad/s about an axis through its centre and perpendicular to its disc. A uniform magnetic field of 0.2T acts perpendicular to the disc. Calculate the induced current if the resistance of the disc is $2\Omega$ .

asked Dec 30, 2016 by suganyadevi.p

1 answer

A circular copper disc 10 cm in radius rotates at $20\pi$ rad/s about an axis through its centre and perpendicular to its disc. A uniform magnetic field of 0.2T acts perpendicular to the disc. Calculate the potential difference developed between the axis of the disc and the rim.

asked Dec 30, 2016 by suganyadevi.p

1 answer

A wheel with 50 metallic spokes each 0.5 m long is rotated with an angular speed of 12 radian /sec, in a plane normal to the earth's magnetic field. If the magnitude of the field is $0.5 \times 10^{-4}$ T, calculate the emf induced between the axle and the rim of the wheel.

asked Dec 30, 2016 by suganyadevi.p

1 answer

A cylindrical bar magnet is kept along the axis of a circular coil and near it as shown in the fig. Will there be any induced e.m.f at the terminals of the coil, when the magnet is rotated about an axis perpendicular to the length of the magnet?

asked Dec 30, 2016 by suganyadevi.p

1 answer

A cylindrical bar magnet is kept along the axis of a circular coil and near it as shown in the fig. Will there be any induced e.m.f at the terminals of the coil, when the magnet is related about its own axis.

asked Dec 30, 2016 by suganyadevi.p

1 answer

A horizontal straight wire $10 \;cm$ long expending from east to west is falling with a speed of $5.0\; m/s$ at right angles to the horizontal component of the earth's magnetic field $0.30 \times 10^{-4}\;wb/m^2$ . Which end of the wire is at the higher electrical potential ?

asked Dec 30, 2016 by priyanka.c

1 answer

A horizontal straight wire $10 \;cm$ long expending from east to west is falling with a speed of $5.0\; m/s$ at right angles to the horizontal component of the earth's magnetic field $0.30 \times 10^{-4}\;wb/m^2$ . What is the direction of the induced $emf$ .

asked Dec 30, 2016 by priyanka.c

1 answer

A circular coil of radius 8.0 cm and 20 turns rotates about its vertical diameter with an angular speed of $50 rad s^{-1}$ in a uniform horizontal magnetic field of magnitude $3 \times 10^{-2} T$ . It the coil forms a closed loop of resistance $10 \Omega$ , calculate the power dissipated as heat.

asked Dec 30, 2016 by suganyadevi.p

1 answer

A circular coil of radius 8.0 cm and 20 turns rotates about its vertical diameter with an angular speed of $50 rad s^{-1}$ in a uniform horizontal magnetic field of magnitude $3 \times 10^{-2} T$ . Calculate the average emf.

asked Dec 30, 2016 by suganyadevi.p

1 answer

A circular coil of radius 8.0 cm and 20 turns rotates about its vertical diameter with an angular speed of 50 $rad s^{-1}$ in a uniform horizontal magnetic field of magnitude $3 \times 10^{-2} T$ . Calculate the maximum emf induced in the coil.

asked Dec 30, 2016 by suganyadevi.p

1 answer

Write a expression for mutual inductance of two coaxial solenoids.

asked Dec 30, 2016 by suganyadevi.p

1 answer

Why are resistance coils usually double wound?

asked Dec 30, 2016 by suganyadevi.p

1 answer

The rate of charge of magnetic flux has same units as induced e.m.f. Say true or false.

asked Dec 30, 2016 by suganyadevi.p

1 answer

Why does a metallic piece very hot when it is surrounded by a coil carrying high frequency alternating current??

asked Dec 30, 2016 by suganyadevi.p

1 answer

A magnetic field of flux density $1.0 wb m^{-2}$ acts normal to a 80 turn coil of 0.01 m^2 area. Find the e.m.f induced in it, if this coil is removed from the field in 0.1 second.

asked Dec 30, 2016 by suganyadevi.p

1 answer

A conducting circular loop is placed in a uniform magnetic field B = 0.020 T with its plane perpendicular to the field. The radius of the loop starts shrinking at a constant rate of 1.0 mm/s. Find the induced e.m.f in the loop at an instant when the radius is 2cm?

asked Dec 30, 2016 by suganyadevi.p

1 answer

Current in a circuit falls from $5.0 A$ to $0.0 A$ in $0.1 S$ . If an average $emf$ of $200 V$ induced, given an estimate of the self-inductance of the circuit.

asked Dec 30, 2016 by priyanka.c

1 answer

A conducting wire of 100 turns is wound over 1cm near the centre of a solenoid of 100 cm length and 2 cm radius having 1000 turns. Calculate the coefficient of mutual inductance of the two solenoids.

asked Dec 30, 2016 by suganyadevi.p

1 answer

SI unit of magnetic flux is

asked Dec 30, 2016 by suganyadevi.p

1 answer

The magnetic flux linked with a coil is $\phi = (3t^2 - 2t + 1)$ milli weber. The e.m.f induced in the coil at t = 1 sec is:

asked Dec 30, 2016 by suganyadevi.p

1 answer

A wire of length 2m moves with a speed of 5 m/s perpendicular to a magnetic field of induction $0.1 wb/m^2$ . The emf induced in the wire is

asked Dec 30, 2016 by suganyadevi.p

1 answer

Amount of change induced in a circuit of resistance R is given by

asked Dec 30, 2016 by suganyadevi.p

1 answer

A horizontal straight wire $10 \;cm$ long expending from east to west is falling with a speed of $5.0\; m/s$ at right angles to the horizontal component of the earth's magnetic field $0.30 \times 10^{-4}\;wb/m^2$ . What is the instantaneous value of the $emf$ induced in the wire ?

asked Dec 30, 2016 by priyanka.c

1 answer

A solenoid coil has 50 turns per cm along its length and a cross sectional area of $4cm^2$ , 200 turns of another wire are wound round the first solenoid co-axially. The two coils are electrically insulated from each other. Calculate the mutual inductance between the two coils.

asked Dec 30, 2016 by suganyadevi.p

1 answer

Two coils have mutual inductance of 1.5 henry. If current in primary circuit is raised to 5 ampere in one millisecond after closing the circuit, what is the e.m.f induced in the secondary??

asked Dec 30, 2016 by suganyadevi.p

1 answer

An e.m.f of 250 microvolt in induced in a coil when current in it changes from 10A to 6A in 0.4 second. What is the self inductance of the coil?

asked Dec 30, 2016 by suganyadevi.p

1 answer

As soon as current is switched on a high voltage line, the bird sitting on it flies away. Why??

asked Dec 30, 2016 by suganyadevi.p

1 answer

A circular coil of radius $0.8\;cm$ and $20 \;turns$ is rotated about its vertical diameter with an angular speed of $50\; rad/s$ in a uniform horizontal magnetic field of magnetic $3.0 \times 10^-{2} T.$ Obtain the maximum and average $emf$ induced in the coil. If the coil forms a closed -loop of resistance $10 \Omega$ , where does the power come from ?

asked Dec 30, 2016 by priyanka.c

1 answer

The magnetic flex through a coil perpendicular to its plane and directed into paper is varying according to the relation $\phi = (5t^2 + 10t + 5)$ milliwebers. Calculate the e.m.f induced in the loop.

asked Dec 30, 2016 by suganyadevi.p

1 answer

A 2m long solenoid with diameter 4 cm and 2000 turns has a secondary of 1000 turns wound closely near it mid point. Calculate the mutual inductance between the two coils.

asked Dec 30, 2016 by suganyadevi.p

1 answer

An aircraft with a wingspan of 40m flies with a speed of 1080 $km hr^{-1}$ in the eastward direction at a constant altitude in the northern hemisphere where the vertical component of earth's magnetic field is $1.75 \times 10^{-5} T$ . Find the emf that develops between the tips of the wings.

asked Dec 30, 2016 by suganyadevi.p

1 answer

A circular coil of radius $0.8\;cm$ and $20 \;turns$ is rotated about its vertical diameter with an angular speed of $50\; rad/s$ in a uniform horizontal magnetic field of magnetic $3.0 \times 10^-{2} T.$ Obtain the maximum and average $emf$ induced in the coil. If the coil forms a closed -loop of resistance $10 \Omega$ , calculate the average power loss due to Joule heating.

asked Dec 30, 2016 by priyanka.c

1 answer

A 12v battery connected to a $6 \Omega$ , 10H coil through a switch drives a constant current in the circuit. Th switch is suddenly opened. Assuming that it took 1 millisecond to open the switch. Calculate the average e.m.f induced across the coil.

asked Dec 30, 2016 by suganyadevi.p

1 answer

A circular coil of radius $0.8\;cm$ and $20 \;turns$ is rotated about its vertical diameter with an angular speed of $50\; rad/s$ in a uniform horizontal magnetic field of magnetic $3.0 \times 10^-{2} T.$ Obtain the maximum and average $emf$ induced in the coil. If the coil forms a closed -loop of resistance $10 \Omega$ , calculate the maximum value of current in the coil.

asked Dec 29, 2016 by priyanka.c

1 answer

A $1.0m$ long metallic rod is rotated with an angular frequency of $400 rad/s$ about an axis normal to the rod passing through its one end. The other end of the rod is in contact with a circular metallic ring. A constant and uniform magnetic field of $0.5 \;T$ parallel to the axis exists everywhere. Calculate the $emf$ developed between the centre and the ring.

asked Dec 29, 2016 by priyanka.c

1 answer

A rectangular wire loop of slides $8 \;cm$ and $2\;cm$ with a small cut is moving out of a region of uniform field of magnitude $0.3T$ directed normal to the loop. What is the $emf$ developed across the cut if the velocity of the loop is $1\;cm/s$ in a direction normal to the shorter side of the loop. For how long does induced voltage last in each case.

asked Dec 29, 2016 by priyanka.c

1 answer

A rectangular wire loop of slides $8 \;cm$ and $2\;cm$ with a small cut is moving out of a region of uniform field of magnitude $0.3T$ directed normal to the loop. What is the $emf$ developed across the cut if the velocity of the loop is $1\;cm/s$ in a direction normal to the longer side. How long will the induced current $V$ last.

asked Dec 29, 2016 by priyanka.c

1 answer

A long solenoid with $15\; turns\; per\; cm$ has a small loop of area $2.0cm^2$ placed inside the solenoid normal to its axis. If the current carried by the solenoid changes steadily from $2.0 A \; to \;4.0 A$ in $0.1 S ,$ what is the induced $emf$ in the loop while the current is changing?

asked Dec 29, 2016 by priyanka.c

1 answer

Use Lenz's law to determine the direction of induced current in the situation described by figure.

A circular loop being deformed in a narrow straight wire.

asked Dec 29, 2016 by priyanka.c

1 answer

Use Lenz's law to determine the direction of induced current in the situations described by figure
A wire of irregular shape turning into a circular shape.

asked Dec 29, 2016 by priyanka.c

1 answer

Current (I) decreasing at a steady state.

asked Dec 29, 2016 by priyanka.c

1 answer

Predict the direction of induced current in situation described above.

asked Dec 29, 2016 by priyanka.c

1 answer

Rheostat setting being changed.

asked Dec 29, 2016 by priyanka.c

1 answer

A magnetic field B = $B_{\circ} sin(\omega t)\hat{k}$ covers a large region where a wire AB slides smoothly over two parallel conductors separated by a distance d, as shown in the fig. The wires are in the x - y plane. The wire AB (of length d) has resistance R and the parallel wires have negligible resistance. If AB is moving velocity $\upsilon$ , what is the current in the circuit?

asked Dec 29, 2016 by suganyadevi.p

1 answer

There are two coils A and B separated by some distance. If a current of 2A flows through A, a magnetic flex of $10^{-2}$ wb passes through B (no current through B). If no current passes through A and a current of 1A passes through B, what is the flex through A?

asked Dec 29, 2016 by suganyadevi.p

1 answer

A (current vs time) graph of the current passing through a solenoid is shown in the fig. For which time is the back electromotive force (u) a maximum? If the back emf at t = 3s is e, find the emf at t = 40s

asked Dec 29, 2016 by suganyadevi.p

1 answer

A (current vs time) graph of the current passing through a solenoid is shown in the fig. For which time is the back electromotive force (u) a maximum? If the back emf at t = 3s is e, find the emf at t = 15s

asked Dec 29, 2016 by suganyadevi.p

1 answer

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