Atoms — Physics STD 12 Science — Question

A radioactive material undergoes decay by ejecting electrons. The electron ejected in this process is:

Assuming that universe is expanding, if the spectrum of light coming from a star which is going away from earth is tested, then in the wavelength of light

(a) There will be no change

(b) The spectrum will move to infrared region

(c) The spectrum will seems to shift to ultraviolet side

(d) None of the above

Free ²³⁸U nuclei kept in a train emit alpha particles. When the train is stationary and a uranium nucleus decays, a passenger measures that the separation between the alpha particle and the recoiling nucleus becomes x in time t after the decay. If a decay takes place when the train is moving at a uniform speed v, the distance between the alpha particle and the recoiling nucleus at a time t after the decay, as measured by the passenger will be:

Two identical cycle wheels (geometrically) have different number of spokes connected from center to rim. One is having 20 spokes and the other having only 10 (the rim and the spokes are resistanceless). One resistance of value R is connected between center and rim. The current in R will be.

The earth’s magnetic field always has a vertical component except at the:

For a series LCR circuit the power loss at resonance is : -

The voltage V and current I graph for a conductor at two different temperatures  and   are shown in the figure. The relation between   and  is

(a)

(b)

(c)

(d)

Two parallel pillars are 11 km away from an observer. The minimum distance between the pillars so that they can be seen separately will be

(a) 3.2 m

(b) 20.8 m

(c) 91.5 m

(d) 183 m