In a single slit diffraction experiment first minimum for red light (660 nm) coincides with first maximum of some other wavelength l'. The value of l' is
|
(a) 4400 Å |
(b) 6600 Å |
(c) 2000 Å |
(d) 3500 Å |
(a) 4400 Å
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Assertion : Thin films such as soap bubble or a thin layer of oil on water show beautiful colours when illuminated by white light.
Reason : It happens due to the interference of light reflected from the upper surface of the thin film.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
A photodetector is made from a semiconductor In 0.53Ga 0.47As with Eg = 0.73 eV. What is the maximum wavelength, which it can detect
|
(a) 1000 nm |
(b) 1703 nm |
(c) 500 nm |
(d) 173 nm |
An electron (charge = 1.6 
) is accelerated through a potential of 100,000 V. The energy acquired by the electron is
|
(a) 1.6 |
(b) 1.6 |
(c) 0.53 |
(d) 1.6 |
Size of nucleus is of the order of
|
(a) |
(b) |
(c) |
(d) |
A point source of light is placed 4 m below the surface of water of refractive index 5 / 3. The minimum diameter of a disc which should be placed over the source on the surface of water to cut–off all light coming out of water is
|
(a) 2 m |
(b) 6 m |
(c) 4 m |
(d) 3 m |
The time period of oscillation of a freely suspended bar magnet with usual notations is given by
(a) T = 2π
|
(b) T = 2π
|
(c) T =
|
(d) T = 2π
|
If R is the Rydberg’s constant for hydrogen the wave number of the first line in the Lyman series will be
|
(a) |
(b) |
(c) |
(d) 2R |
A pendulum bob of mass 30.7 
and carrying a charge 
is at rest in a horizontal uniform electric field of 20000 V/m. The tension in the thread of the pendulum is (g = 9.8 
|
(a) 3 |
(b) 4 |
(c) 5 |
(d) 6 |
