If a transformer of an audio amplifier has output impedance 8000 Ω and the speaker has input impedance of 8 Ω, the primary and secondary turns of this transformer connected between the output of amplifier and to loud speaker should have the ratio
1000 : 1
100 : 1
1 : 32
32 : 1
In the electromagnetic spectrum, the visible spectrum lies between
radiowaves and microwaves
infrared and ultraviolet rays
microwaves and infrared spectrum
X-ray and γ-ray spectrum
Maxwell in his famous equation of electromagnetism introduced the concept
AC current
DC current
displacement current
impedance
Out of the following electromagnetic radiations, which has the shortest wavelength ?
Radiowaves
Infrared
X-rays
Visible light
C.
X-rays
X-rays have shortest wavelength out of the given radiations.
A charged oil drop of mass 9.75 x 10-15 kg and charge 30 x 10-16 C is suspended in a uniform electric field existing between two parallel plates. The field between the plates, taking (g = 10 ms-2) is
3.25 V/m
300 V/m
325 V/m
32.5 V/m
In Young's double slit experiment, the width of one of the slits is slowly increased to make it twice the width of the other slit. Then in thei nterference pattern
the intensity of maxima increase while that of minima decrease
the intensities of both maxima and minima decrease
the intensities of both maxima and minima increase
the intensity of maxima decrease while that of minima increase
Two coherent sources whose intensity ratio is 81 : 1 produce interference fringes. The ratio of minimum to maximum intensity, i,e Imin : Imax is
16 : 25
9 : 1
1 : 9
25 : 16
An infinitely long rod lies along the axis of concave mirror of focal length f. The near end of the rod is at a distance x > f from the mirror. Then the length of the image of the rod is
A beaker containing a liquid appears to be half when it is actually two third full. The refractive index of liquid is
7/6
6/5
4/3
5/4
If h1 and h2 are the heights of the images in conjugate position of a convex lens, then the height of the object is
h1 + h2
h1 − h2
h1/h2