A compass needle whose magnetic moment is 60 A m² pointing geographical north at a certain place, where the horizontal component of the earth’s magnetic field is 40 μWb m², experiences a torque
0.2 × 10⁻³ Nm. The declination at this place is
0.2 × 10⁻³ Nm. The declination at this place is
If the angle of dip at two places are 30° and 45° respectively, then the ratio of horizontal components of the earth’s magnetic field at the two places will be
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
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
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
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 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 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
Cathode rays travelling from west to east enter into region of electric field directed towards south to north in the plane of paper. The deflection of cathode rays is towards:
(A) East
(B) West
(C) North
(D) South
The fringe width (β) of a diffraction pattern and the slit width d are related as:
(a) β ∝ d
(b) β ∝1/d
(c) β ∝ √d
(d) β ∝ 1/\(d^2\)
When tiny circular obstacle is placed in the path of light from a distance source , a bright spot is seen at the centre of the obstacle.
I. It happens due to
II. Polarization of light waves
III. Diffraction of light waves
IV. Interference of light waves
V. Scattering of light waves
The light sources used in Young’s double slit experiment are:
(A) Incoherent
(B) Coherent
(C) White light
(D) Blue-green-red Light.
The magnetic flux linked with a coil is given by an equation Φ = 5t² + 2t + 3. The induced e.m.f. in the coil at the third second will be
(A) 32 units
(B) 54 units
(C) 40 units
(D) 65 units
To convert a moving coil galvanometer into on ammeter of given range, we must connect:
(a) A suitable low resistance in series
(b) A suitable low resistance in parallel
(c) A suitable high resistance in parallel
(d) A suitable high resistance in series
A parallel plate air capacitor has a capacitance 18μF. If the distance between the plates is tripled and a dielectric medium is introduced, the capacitance becomes 72μF. The dielectric constant of the medium is
(a) 4
(b) 9
(c) 12
(d) 2