In a series L-C-R circuit, an alternating emf (V) and current (i) are given by the equation . The average power dissipated in the circuit over a cycle of AC is
zero
The process of superimposing message signal on high frequency carrier wave is called
amplification
demodulation
transmission
modulation
A plane glass plate is placed over a various coloured letters (violet, green, yellow, red). The letter which appears to raised more is
red
yellow
green
violet
A ray of light passes through four transparent media with refractive index n1, n2, n3 and n4 as shown in the figure. The surfaces of all media are parallel.
If the emergent ray DE is parallel to incident ray AB, then
n1 = n4
n2 = n4
n3 = n4
Focal length of a convex lens is 20 cm and its refractive index is 1.5. It produces an erect, enlarged image if the distance of the object from the lens is
40 cm
30 cm
15 cm
20 cm
A ray of light suffers a minimum deviation when incident on an equilateral prism of refractive index . The angle of deviation is
30°
45°
60°
50°
In Young's double slit experiment, the source is white light. One slit is covered with red filter and the other with blue filter. There shall be
alternate red and blue fringes
alternate dark and pink fringes
alternate dark and yellow fringes
no interference
Light of wavelength 600 nm is incident normally on a slit of width 0.2 mm. The angular width of central maxima in the diffraction pattern is (measured from minimum to minimum)
6 × 10-3 rad
4 × 10-3 rad
2.4 × 10-3 rad
4.5 × 10-3 rad
A.
6 × 10-3 rad
λ = 600 nm = 600 × 10-9 m
d = 0.2 mm = 0.2 × 10-3 m
Since, linear width of central maximum,
x = (2θ) D
where, 2θ : Angular width of central maximum
We know that,
Angular width, 2θ,
For what distance ray optics is good approximation when the aperture is 4 mm and the wavelength of light is 400 nm ?
24 m
40 m
18 m
30 m