Biological importance of Ozone layer is
|
(a) It stops ultraviolet rays |
|
(b) Ozone rays reduce green house effect |
|
(c) Ozone layer reflects radio waves |
|
(d) Ozone layer controls |
(a) It stops ultraviolet rays
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Energy of electrons can be increased by allowing them
|
(a) To fall through electric potential |
(b) To move in high magnetic field |
|
(c) To fall from great heights |
(d) To pass through lead blocks |
Assertion : Cyclotron is a device which is used to accelerate the positive ion.
Reason : Cyclotron frequency depends upon the velocity.
|
(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. |
The ionisation potential of hydrogen atom is 13.6 volt. The energy required to remove an electron in the n = 2 state of the hydrogen atom is
|
(a) 27.2 eV |
(b) 13.6 eV |
(c) 6.8 eV |
(d) 3.4 eV |
When wavelength of incident photon is decreased then
|
(a) Velocity of emitted photo-electron decreases |
|
(b) Velocity of emitted photoelectron increases |
|
(c) Velocity of photoelectron do not charge |
|
(d) Photo electric current increases |
A light ray from air is incident (as shown in figure) at one end of a glass fiber (refractive index m = 1.5) making an incidence angle of 60o on the lateral surface, so that it undergoes a total internal reflection. How much time would it take to traverse the straight fiber of length 1 km
| (a) 3.33 m sec | (b) 6.67 m sec | (c) 5.77 m sec | (d) 3.85 m sec |
