MEDIUM
Physics
IMPORTANT
Earn 100

The magnetic field inside a long solenoid of cross-section 15 cm2 is 200 T. This solenoid crosses a square coil of area 2 m2 such that the length of the solenoid is parallel to the axis of coil. The magnetic flux linked through the square coil is x Wb, then what is the value of 10x?

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Important Questions on Electromagnetic Induction and Alternating Currents

MEDIUM
Physics
IMPORTANT
A ring of mass 4 kg is uniformly charged with a linear charge density λ=4 C m-1 and kept on a rough horizontal surface with a friction coefficient of μ=π4. A time-varying magnetic field B=B0t2 is applied in a circular region of radius a a<r perpendicular to the plane of the ring as shown in the figure. Find out the time (in seconds) when the ring just starts to rotate on the surface. ( Take a=5 cmg=10 m s-2 and B0=125 T s-2)
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HARD
Physics
IMPORTANT

A conducting rod pq is sliding on two parallel conducting rods with constant velocity in a uniform magnetic field of induction B=2 Wb m-2 as shown in the figure. The rods are connected with a circuit. What should be velocity of rod pq (in m s-1), if current in 2 Ω resistor is 0.1 A?

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MEDIUM
Physics
IMPORTANT
For a coil having L=2 mH, current flows through it is i=t2e-t, then the time (in second) at which emf becomes zero is-
HARD
Physics
IMPORTANT

In the circuit shown in the figure, S1 remains closed for a long time and S2 remains open. Now S2 is closed and S1 is opened simultaneously. Find out the didt in Amp sec-1 just after that moment

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HARD
Physics
IMPORTANT

The inductors of two LR circuits are placed next to each other, as shown in the figure. The values of the self-inductance of the inductors, resistances, mutual-inductance and applied voltages are specified in the given circuit. After both the switches are closed simultaneously, then total work done by the batteries against the induced EMF in the inductors by the time the currents reach their steady state values is______________mJ

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MEDIUM
Physics
IMPORTANT
An AC circuit drawing power from a source of angular frequency 50 rads-1 has a power factor of 0.6 . In this condition, a resistance of 100 Ω is present and the current is lagging behind the voltage. If a capacitor is connected in series, then the required capacitance (in μF )that will result in a power factor of unity is :
MEDIUM
Physics
IMPORTANT
Power factor of an L-R series circuit is 0.6. and that of a C-R series circuit is 0.5. If the element (L, C and R) of the two circuits are joined in series the power factor of this circuit is found to be 1. The ratio of the resistance in the L-R circuit to the resistance in the C-R circuit is x4, find the value of x.
EASY
Physics
IMPORTANT
A series LCR circuit is designed to resonate at an angular frequency ω0=105 rad s-1. The circuit draws 16 W power from 120 V source at resonance. The value of resistance R in the circuit is _____ Ω.