The potential energy of a charged parallel plate capacitor is \(U_0\). If a slab of dielectric constant K is inserted between the plates, then new potential energy will be
(a) \(U_0\)/K
(b) \(U_0\)K²
(c) \(U_0\)/K²
(d) \(U_0\)²
(a) \(U_0\)/K
(b) \(U_0\)K²
(c) \(U_0\)/K²
(d) \(U_0\)²
(a) \(U_0\)/K
Three capacitors 3 μF, 6 μF and 6 μF are connected in series to a source of 120 volt. The potential difference across the 3 μF capacitor will be
(a) 40 volt
(b) 30 volt
(c) 40 volt
(d) 60 volt
The amount of work required to increase the distance between -6µC and 4µC from 6 cm to 18 cm will be :
(a) 1.8 J
(b) 2.4 J
(c) 1.8 µJ
(d) 2.4 µJ
Equipotential surfaces at a great distance from a collection of charges whose total sum is not zero are approximately
(a) spheres
(b) planes
(c) paraboloids
(d) ellipsoids
The electrostatic potential energy between proton and electron separated by a distance of 1 Å is
(a) 13.6eV
(b) 27.2eV
(c) -14.4eV
(d) 1.44eV
Two capacitors of 3 μF and 6 μF are connected in series with a battery of P.d. 12 V. The P.d. across 3μF and 6μF capacitors respectively will be :
(a) 8 V, 4 V
(b) 6 V, 6 V
(c) 4 V, 8 V
(d) 9 V, 3 V
An electric charge of 425 f μC is removed from a fully charged capacitor of capacitance 8.5μF. Its potential will be lowered by:
(a) 75 V
(b) 100 V
(c) 85 V
(d) 50 V
Minimum number of capacitor of 2μF each required to obtain a capacitance of 5μF will be:
(a) 4
(b) 3
(c) 5
(d) 6
In the phenomenon of diffraction of light, when blue light is used in the experiment instead of red light, then
i. Fringes will become narrower
ii. Fringes will become broader
iii. No change in fringe width
iv. None of the above
A wire in the form of a circular loop, of one turn carrying a current, produces magnetic induction B at the centre. If the same wire is looped into a coil of two turns and carries the same current, the new value of magnetic induction at the centre is-
a) B
b) 4B
c) 2B
d) 8B.
The colours on the soap bubble is due to
(a) Interference
(b) Diffraction
(c) Polarisation
(d) Reflection
Two monochromatic light beams intensities of I and 4I are superposed. The maximum and minimum possible intensities In the resulting beam are
(A) 5I and I
(B) 5I and 3I
(C) 9I and I
(D) 9I and 3I
The electric potential due to point charge 3 nC at distance of 9 cm is
(a) 270 v
(b) 3 v
(c) 300 v
(d) 30 v
The wave-front due to source situated at the infinity is
(A) Spherical
(B) Cylindrical
(C) Plane
(D) Rectangular
Instead of using two slits as in Young’s experiment, if we use two separate but identical sodium lamps, which of the following occur?
(a) general illumination.
(b) widely separate interference.
(c) very bright maximum.
(d) very dark minimum.