Identify the correctly matched pair
Diamagnetic — Gadolinium
Soft ferromagnetic — Alnico
Hard ferromagnetic — Copper
Paramagnetic — Sodium
If the radius of the dees of cyclotron is r, then the kinetic energy of a proton of mass m accelerated by the cyclotron at an oscillating frequency v is
If a magnetic dipole of moment M situated in the direction of a magnetic field B is rotated by 180°, then the amount of work done is
MB
2 MB
Zero
The polarity of induced emf is given by
Ampere's circuital law
Biot-Savart's law
Lenz's law
Fleming's right hand rule
In an L-C-R series circuit, at resonance
the current and voltage are in phase
the impedance is maximum
the current is minimum
the quality factor is independent of R
A conducting ring of radius 1 m kept in a uniform magnetic field B of 0.01 T, rotates uniformly with an angular velocity 100 rads-1 with its axis of rotation perpendicular to B. The maximum induced emf in it is
A step-down transformer increases the input current 4 A to 24 A at the secondary. If the number of turns in the primary coil is 330, the number of turns in the secondary coil is
60
50
55
45
C.
55
By step-down transformer,
It converts a high voltage of low current into a low voltage of high current.
In a plane electromagnetic wave, the electric field of amplitude 1 Vm-1 varies with time in free space. The average energy density of magnetic field is (in Jm-2)
8.86 × 10-12
4.43 × 10-12
17.72 × 10-12
2.21 × 10-12
Which one of the following is the property of a monochromatic, plane electromagnetic wave in free space?
Electric and magnetic fields have a phase difference of
The energy contribution of both electric and magnetic fields are equal.
The direction of propagation is in the direction of electric field E
The pressure exerted by the wave is the product of energy density and the speed of the wave
A plane square sheet of charge of side 0.5 m has uniform surface charge density. An electron at 1 cm from the centre of the sheet experiences a force of 1.6 x 10-12 N directed away from the sheet. The total charge on the plane square sheet is (ε0 = 8.854 × 10-12 C2 m-2 N-1)
16.25 µC
− 22.15 µC
− 44.27 µC
144.27 µC