In a permanent magnet at room temperature,
(a) magnetic moment of each molecule is zero
(b) the individual molecules have non-zero magnetic moment which are all perfectly aligned
(c) domains are partially aligned
(d) domains are all perfectly aligned
(a) magnetic moment of each molecule is zero
(b) the individual molecules have non-zero magnetic moment which are all perfectly aligned
(c) domains are partially aligned
(d) domains are all perfectly aligned
(d) domains are all perfectly aligned
A bar magnet of dipole moment ’m’ cut into two equal pieces transverse to its length. Dipole moment of each part is
a) Remain same
b) m/2
c) 2m
d) none of the above
A steel wire of length l has a magnetic moment M .It is then bent into a semicircular arc. The new magnetic moment is
a) M
b) 2M/π
c) M/l
d) Ml
A current loop placed in a magnetic field behaves like a
a) Magnetic substance
b) Magnetic pole
c) Magnetic dipole
d) all true
If a magnet is cut perpendicular its length into equal parts ,then the pole strength of each pole of the magnet
a) becomes double
b) remains same
c) becomes half
d) None of the above
Magnetic field lines form continuous closed loops
a) magnet is always a dipole
b) magnet is always a monopole
c) magnetic material is permeable
d) none of the above
A current carrying small loop behaves like a small magnet. If A be its area and M its magnetic moment, the current in the loop will be
a) M/A
b) A/M
c) MA
d) A²M
The direction of magnetic dipole moment is always from
a) North pole to south pole
b)Away from North pole outside magnet
c) South pole to North Pole
d) all of the above
In electric arc furnace Cu or Iron is melted due to variation of
(a) current
(b) magnetic field
(c) voltage
(d) electric field
In a circuit with a coil of resistance 3Ω, the magnetic flux changes from 1.0 Wb to 10.0 Wb in 0.3 s. The charge that flows in the coil during this time is
(a) 2.0 C
(b) 3.0 C
(c) 4.0 C
(d) 1.0 C
The ratio of intensities at minima to the maxima in young’s double slit experiment is 9 : 25. Find the ratio of the widths of two slits.
(A) 16: 1
(B) 1: 16
(C) 4 : 1
(D) 1 : 4
In Young’s double slit experiment the distance between the slit and the screen is doubled and the separation between the slit is reduced to half. The fringe width:
(a) is doubled
(b) become four time
(c) is halved
(d) remain unchanged
The condition for Fraunhoffer diffraction from a single slit is that the light wave-front incident on a slit should be
(A) Spherical
(B) Cylindrical
(C) Plane
(D) Rectangular
Two waves having intensities in the ratio of 9:1 produce interference. The ratio of the maximum to the minimum intensity is
I. 9:1
II. 4:1
III. 1:2
IV. 1:3
Two-point charges 2μC and 4μC are placed 2 cm apart. The ratio of the Coulomb’s force experienced by them is
(A) 1: 2
(B) 2: 1
(C) 1: 1
(D) 4: 1