A point source of `gamma`- radiatonhas a half-life of 30 minutes.The intitial count rate recorded by Geiger counter placed 2 m from the source is `360 s^(-1)`.The distnace between the counter and the source is altered.After 1.5 hours,the count rate recorded is `5 s^(-1)`.What is th new distnace between the counter and the source?

Two points are located at a distance of 10 m and 15 m from the source of oscillation .theperiod of oscillation is 0.05 sec and the velocity of the wave is 300 m s^(-1) .What is the phase difference between the oscillation of two points?

The count rate from a radiuactive sample falls from 4.0 xx 10^6 s^(-1) to 1.0 xx 10^6 s^(-1) in 20 hours.What will be the count rate 100 hours after the beginning.

A beam of light of wavelength 600 nm from a distant source falls on a single slit 1.00 mm wide and the resulting diffraction pattern is observed on a screen 2m away. What is the distance between the first dark fringes on either side of the central fringe?

Sketch a graph between frequency of incident radiations and stopping potential for a given photosensitive material. What information can be obtained from the value of the intercept of potential axis? A source of light of frequency of greater than the threshold freuency is placed at a distance of 1 m from the cathode of a photocell? the distnace of hte light sources from the cathode is reduced explain giving reasons, what change will you observe in the Stopping potential.

To conduct Sports Day activities, in your rectangular shaped school ground ABCD, lines have been drawn with chalk powder at a distance of 1m each. 100 Flower pots have been placed at a distance of 1m from each other along AD, as shown in Fig. 7. 12. Niharika runs 1/4 th the distance AD on the 2nd line and posts a green flag. Preet runs 1/5th the distance AD on the eighth line and posts a red flag. What is the distance between both the flags? If Rashmi has to post a blue flag exactly halfway between the line segment joining the two flags, where should she post her flag?

In a Young's double slit experiment,the slits are 1.5 mm apart.When the slits are illuminated by a monochromatic source and the screen is kept 1 m aprat from the slits,width of 10 fringes is measured as 3.93 mm.Calculate the wavelength of light used.What will be the width of 10 figes,when the distance between the slits and the screen is increased by 0.5 m?The source of light used remains the same.

The rear side of a truck is open and a box of 40 kg mass is placed 5 m away from the open end as shown in Fig. 5.22. The coeffcient of friction between the box and the surface below it is 0.15. On a straight road, the truck starts from rest and accelerates with 2 m s^-2 . At what distance from the starting point does the box fall off the truck? (Ignore the size of the box).

A telescope has an objective of diameter of 60 cm. The focal lengths of the objective and eye piece are 2.0 m and 1.0 cm respectively. The telescope is directed to view two distant almost point sources of light (e.g. two stars of a binary). The sources are at roughly the same distance (=10^4 light years) along the line of sight but separated transverse to the line of sight by a distnace of 10^10 m . what will the telescope resolve the two objects i.e. will it see two distinct stars?

A capacitro is made of two circular plates each of radius 0*25 m [Fig 1.09] .It is being charged by an external source.What is the magnetic field at a piont P at adistnce of 0.5 m from the entre of the plates in the plane midway between them,when the charging current is 1 A? .