Arrange the following type of radiations in increasing order of frequency
a) radiation from microwave oven.
b) amber light from traffic signil
c) radiation from FM radio
e) cosmic rays from outer space and
X-rays.

X-rays and radiations from atomic energy plants : Artificial radiations ::"__________": Natural radiation

Name the most harmful radiation entering the earth's atmosphere from the outer space.?

Write whether the following Statements are true or false, giving suitable explanation for the same: X-rays and radiations from atomic energy plants are natural radiations.

Answer the following questions The observations made by swarali while doing the experiment are given below. Based on these write answers to the questions: Swarali found that the light ray trvelling from the denser medium to a rarer medium goes away from the normal. If the angle of incidence (i) is raised by Swarali, the angle of refraction (r) went on increasing . However after certain value of the angle of incidence. the light ray is seen to return back into the denser medium What is the process of reflection of incident ray into a denser medium called ?

Answer the following questions The observations made by swarali while doing the experiment are given below. Based on these write answers to the questions: Swarali found that the light ray trvelling from the denser medium to a rarer medium goes away from the normal. If the angle of incidence (i) is raised by Swarali, the angle of refraction (r) went on increasing . However after certain value of the angle of incidence. the light ray is seen to return back into the denser medium Draw the diagram of three observations made by swarali.

Answer the following questions The observations made by swarali while doing the experiment are given below. Based on these write answers to the questions: Swarali found that the light ray trvelling from the denser medium to a rarer medium goes away from the normal. If the angle of incidence (i) is raised by Swarali, the angle of refraction (r) went on increasing . However after certain value of the angle of incidence. the light ray is seen to return back into the denser medium What is the specific value of angle i called ?

On a photosensitive material, when frequency of incident radiation is increased by 30% kinetic energy of emitted photoelectrons increases from 0.4 eV to 0.9 eV . The work function of the surface is

When the light of frequency 2 v_(0) (where v_(0) is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is v_(1) . When the frequency of the incident radiation is increased to 5 v_(0) , the maximum velocity of electrons emitted from the same plate is v_(2) . the ratio of v_(1) to v_(2) is