Recent questions tagged #mcq

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In the circuit shown the capacitor has charge Q. At `t=0` sec the key is closed. The charge on the capacitor at the instant potential difference across the inductor `L_1` is zero,

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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The figure shows a rod of length `l` with points A and B on it. The rod is moved in a uniform magnetic field `(B_0)` in different ways as shown. In which case potential difference `(V_A–V_B)` between `A & B` is

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A bent rod `PQR (PQ = QR =l)` shown here is rotating about its end P with angular speed `omega` in a region of transverse magnetic field of strength

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A conducting loop is kept so that its center lies at the origin of the coordinate system. A magnetic field has the induction B pointing along Z-axis as shown in the

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Initially key was placed on (1) till the capacitor got fully charged. Key is placed on (2) at `t=0`. The time when the energy in both capacitor and inductor will be

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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For an LCR series circuit, phasors of current i and applied voltage `V=V_0 sinomegat` are shown in diagram at `t =0`. Which of the following is/are

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A cylindrical space of radius R is filled with a uniform magnetic induction B parallel to the axis of the cylinder. If `(dB)/(dt) =` constant, the graph, showing the variation of induced electric field with distance r from the axis of cylinder, isConsider a conducting circular loop placed in a magnetic field as shown in figure. When magnetic field changes with time, magnetic flux also changes and emf `e=-(dphi)/(dt)` is induced. If resistance of loop is R then induced current is `i=e/R`. For current, charges must have non–zero average velocity. Magnetic force cannot make the stationary charges to move. Actually

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A line charge `lambda` per unit length is pasted uniformly onto the rim of a wheel of mass m and radius R. The wheel has light non–conducting spokes and is free to rotate about a vertical axis as shown in figure.A uniform magnetic field B exist as shown in figure. What is the angular velocity of the wheel when the field is suddenly switched off?Consider a conducting circular loop placed in a magnetic field as shown in figure. When magnetic field changes with time, magnetic flux also changes and emf `e=-(dphi)/(dt)` is induced. If resistance of loop is R then

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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The emf across `AB` at `t=l/(2v)` isA conducting square wire frame ABCD of side `l` is pulled by horizontal force so that it moves with constant velocity v. A uniform magnetic field of strength B is existing perpendicular to the plane of wire. The resistance per unit length of wire is `lambda` and negligible self inductance. If at `t= 0,` frame is just at the boundary of magnetic field.

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Potential difference across BC at time `t=l/(2v)` isA conducting square wire frame ABCD of side `l` is pulled by horizontal force so that it moves with constant velocity v. A uniform magnetic field of strength B is existing perpendicular to the plane of wire. The resistance per unit length of wire is `lambda` and negligible self inductance. If at `t= 0,` frame is just at the boundary of magnetic field.

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Find the applied horizontal force on BC, (F) as a function of time `'t' (t < l/v)`A conducting square wire frame ABCD of side `l` is pulled by horizontal force so that it moves with constant velocity v. A uniform magnetic field of strength B is existing perpendicular to the plane of wire. The resistance per unit length of wire is `lambda` and negligible self inductance. If at `t= 0,` frame is just at the boundary of magnetic field.

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A toroid of n turns, mean radius R and cross-sectional radius a carries current I. It is placed on a horizontal table taken as x-y plane. Its magnetic moment

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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The magnetic field of Earth can be modelled by that of a point dipole placed at the centre of the Earth. The dipole axis makes an angle of 11.3° with the axis of Earth. At Mumbai, declination is nearly zero.

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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In a permanent magnet at room

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Consider the two idealized systems: (i) a parallel plate capacitor with large plates and small separation and (ii) a long solenoid of length L >> R, radius of cross-section. In (i) E is ideally treated as a constant between plates and zero outside. In (ii) magnetic field is constant inside the solenoid and zero outside. These idealised assumptions, however, contradict fundamental laws as

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A paramagnetic sample shows a net magnetisation of 8 Am–1 when placed in an external magnetic field of 0.6T at a temperature of 4K. When the same sample is placed in an external magnetic field of 0.2 T at a temperature of 16K, the magnetisation will

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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S is the surface of a lump of magnetic

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The primary origin(s) of magnetism lies

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A long solenoid has 1000 turns per metre and carries a current of 1 A. It has a soft iron core of μr = 1000. The core is heated beyond the Curie temperature,

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Essential difference between electrostatic shielding by a conducting shell and magnetostatic shielding is due

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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