NEET Physics Electromagnetic Induction Class 12 Questions

The flux linked with a circuit is given by ϕB = t² + 2. The graph between time (X⁻axis) and induced emf (Y⁻axis) will be a

Two coils are placed near each other. When the current in one coil is changed at the rate of 5 A/s, an emf of 2 mV is induced in the other. The mutual inductance of the two coils is

Dimensional formula of mutual inductance is

A transformer is used to light 140 W, 24 V lamp from 240 V ac mains. If the main current is 0.7 Å, the efficiency of the transformer is

A metallic rod of length 'L' is rotated with an angular speed of 'ω' normal to a uniform magnetic field 'B' about an axis passing through one end of rod as shown in figure. The induced emf will be:

Statement I: If the number of turns in the coil of a moving coil galvanometer is doubled then the current sensitivity becomes double. Statement II: Increasing current sensitivity of a moving coil galvanometer by only increasing the number of turns in the coil will also increase its voltage sensitivity in the same ratio. In the light of the above statement, choose the correct answer from the options given below:

The induced emf can be produced in a coil by

A wire of irregular shape turning into a circular shape in a magnetic field which is directed into the paper. The direction of induced current is then

The mutual inductance of two coils, in a given orientation is 50 mH. If the current in one of the coils changes as i = 1.0sin(100πt + π/3) A, the peak value of emf (in volt) induced in the other coil will be

When the current changes from +2 Å to –2 Å in 0.05 second, an e.m.f. of 8 V is induced in a coil. The coefficient of self-induction of the coil is

A wheel with 10 metallic spokes each 0.5 m long is rotated with a speed of 120 rev/min in a plane normal to the earth's magnetic field at the place. If the magnitude of the magnetic field is 0.4 G, what is the induced emf between the axle and the rim of the wheel?

The current (I) in the inductance is varying with time according to the plot shown in figure. Which one of the following is the correct variation of voltage with time in the coil?

A conducting circular loop is placed in a uniform magnetic field of 0.04 T with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at 2 mm/s. The induced emf in the loop when the radius is 2 cm is

A rectangular wire loop of sides 8 cm and 3 cm with a small cut, is moving out of a region of uniform magnetic field of magnitude 0.3 T directed normal to the plane of the loop. The emf developed across the cut, if the velocity of the loop is 2 cm s⁻¹, in a direction normal to the shorter side of the loop, will be:

A 2 amp current is flowing through two different small circular copper coils having radii ratio 1:2. The ratio of their respective magnetic moments will be

A sphere of radius R is cut from a larger solid sphere of radius 2R as shown in the figure. The ratio of the moment of inertia of the smaller sphere to that of the rest part of the sphere about the Y⁻axis is:

In the above diagram, a strong bar magnet is moving towards solenoid-2 from solenoid-1. The direction of induced current in solenoid-1 and that in solenoid-2, respectively, are through the directions:

In an ideal transformer, the turns ratio is \( \frac{N_p}{N_s} = \frac{1}{2} \). The ratio \( V_s : V_p \) is equal to (the symbols carry their usual meaning):

A 12 V, 60 W lamp is connected to the secondary of a step down transformer, whose primary is connected to ac mains of 220 V. Assuming the transformer to be ideal, what is the current in the primary winding?

The magnetic energy stored in an inductor of inductance 4 μH carrying a current of 2 A is:

A wire carrying a current <em>I</em> along the positive <em>x</em>-axis has length <em>L</em>. It is kept in a magnetic field <span style="display:inline-block;position:relative;padding-top:0.4em;">B<span style="position:absolute;top:0;left:50%;transform:translateX(-50%);font-size:0.7em;">→</span></span> = (2î + 3ĵ − 4k̂) T. The magnitude of the magnetic force acting on the wire is:

A square loop of side 1 m and resistance 1 Ω is placed in a magnetic field of 0.5 T. If the plane of loop is perpendicular to the direction of magnetic field, the magnetic flux through the loop is:

A big circular coil of 1000 turns and average radius 10 m is rotating about its horizontal diameter at 2 rad s⁻¹. If the vertical component of earth’s magnetic field at that place is 2 × 10⁻⁵ T and electrical resistance of the coil is 12.56 Ω, then the maximum induced current in the coil will be:

A capacitor of capacitance ‘C’, is connected across an ac source of voltage V, given by V = V₀ sinωt. The displacement current between the plates of the capacitor, would then be given by:

Two conducting circular loops of radii R₁ and R₂ are placed in the same plane with their centres coinciding. If R₁ >> R₂, the mutual inductance M between them will be directly proportional to :

A 800 turn coil of effective area 0.05 m² is kept perpendicular to a magnetic field 5 × 10⁻⁵ T. When the plane of the coil is rotated by 90° around any of its coplanar axis in 0.1 s, the e.m.f. induced in the coil will be:

In which of the following devices, the eddy current effect is not used?

A battery consists of a variable number 'n' of identical cells (having internal resistance 'r' each) which are connected in series. The terminals of the battery are short-circuited and the current I is measured. Which of the graphs shows the correct relationship between I and n?

The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance

A long solenoid of diameter 0.1 m has 2 × 10⁴ turns per metre. At the centre of the solenoid, a coil of 100 turns and radius 0.01 m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0 Å from 4 Å in 0.05 s. If the resistance of the coil is 10π² Ω, the total charge flowing through the coil during this time is

A long solenoid has 1000 turns. When a current of 4 Å flows through it, the magnetic flux linked with each turn of the solenoid is 4 × 10⁻³ Wb. The self-inductance of the solenoid is

A conducting square frame of side 'a' and a long straight wire carrying current I are located in the same plane as shown in the figure. The frame moves to the right with a constant velocity v. The e.m.f. induced in the frame will be proportional to

Following figures show the arrangement of bar magnets in different configurations. Each magnet has magnetic dipole moment m. Which configuration has highest net magnetic dipole moment?

A thin semicircular conducting ring (PQR) of radius r is falling with its plane vertical in a horizontal magnetic field B, as shown in figure. The potential difference developed across the ring when its speed is v, is

A transformer having efficiency of 90% is working on 200 V and 3 kW power supply. If the current in the secondary coil is 6 Å, the voltage across the secondary coil and the current in the primary coil respectively are

The primary of a transformer when connected to the battery of 10 Volt draws a current of 1 mA. The number of turns of the primary and secondary windings are 50 and 100 respectively. The voltage in the secondary and the current drawn by the circuit in the secondary are respectively:

A current of 2.5 Å flows through a coil of inductance 5 H. The magnetic flux linked with the coil is: