2-A)draw the graph showing the variation of no of scattered alpha particle with scattering angle in Geiger – Marsden Experiment . B)plot the graph photo current vs collector potential i) same intensity vs different frequency ii) same frequency vs different intensity
3)write the characteristics of a p-n junction which make it suitable for rectification .
4)Define the term- distance of closest approach . How will it be affected ,for an ∝-particle ,if kinetic energy of the particle is doubled ?
5)A point source in air is kept 24cm in front of a concave spherical glass surfrace (μg= 1.5)radius of curvature 60cm . find the nature of the image formed and its distance from the point source .
6) Calculate the energy released in MeV in the following reaction :
2H1 + 3H 1 —- 2He 4 +n given m(2H1= 2.014102u) m(3H1= 3.016049u)
m(4He2= 4.002603u ) mn= 1.008665u find energy released ?
7)Explain with the help of a suitable diagram , the phenomenon on which an optical fibre works . mention any two uses of optical fibres.
8)a) A parallel beam of light of wavelength 600nm is incident normally on a slit width 0.2mm,if the resulting diffraction patteren is observed on a screen 1m away ,find the distance of i) first minimum ii) second maximum from central maximum or
b) A thin equiconvex lens of radius of curvature R made of material of refractive index μ1 is kept coaxially in contact with an equiconcave lens of same radius of curvature and refractive index (μ2 > μ1) Find (i) the ratio of their powers (ii) the power of the combination and its nature
9)photoelectrons are emitted from a metal surface when illuminated with uv light of wavelength 330nm. The minimum amount of energy required to emit the electron from surface is 3.5 * 10 -19 J . calculate (i) the energy of the incident radiation (ii) the kinetic enegy of the photoelectron
10) state the working principle of an LED. Write any two important advantages and disadvantages of LED .
11)a) (i) Monochromatic light is incident on a surface separating two media . The frequency of the light after refraction remains unaffected but its wavelenghth changes . why ?
ii) The frequency of an electromagnetic radiation is 1*10 11 Hz. Identify the radiation and mention its two uses .
b) (i) Trace the path of a ray of light pq which is incident at an angle I on one face of a glass prism of angle A . it then emerges out from the other face at an angle e , use the ray diagram to prove that the angle through which the ray is deviated is given by δ = I + e – A
(ii) what will be the minimum value of δ if the ray passes symmetrically through the prism ?
12) The principle of superposition is used to understand the phenomenon of interference of light waves. The principle states that at a particular point, the resultant displacement produced by a number of waves is the vector sum of the displacements produced by each wave. Light waves from two coherent sources produce interference pattern. Thomas Young devised a way to obtain two coherent sources using two identical pinholes (S₁ and S₂) illuminated by a single monochromatic pinhole source S. Using these sources in his experiment known as Young’s double slit experiment, Young studied the interference pattern. The pattern consists of alternate bright and dark fringes. The distance between two successive bright or dark fringes depends on the distance between S₁ and S₂, the distance of the screen from the plane of S₁ S₂, and the wavelength of light used.
QUESTION 1
Consider the following waves: (i) y₁ = a sin ωt (ii) y₂ = a sin 2ωt (iii) y₃ = a sin(2ωt + φ) (iv) y₄ = a sin (4ωt + π/2)
Which pair of the waves coming from two sources S₁ and S₂ will produce interference? A. (i) and (ii) B. (ii) and (iii) C. (iii) and (iv) D. (iv) and (i)
QUESTION 2
Two light waves of the same intensity I₀ each, having a path difference of λ/4, emanating from two coherent sources, meet at a point. The resultant intensity at the point will be A. Zero B. I₀ C. 2I₀ D. 4I₀
QUESTION 3
Vandana performs Young’s double slit experiment by using orange,green ,red light successfully . if the fringe width measured in three cases are w1,w2,w3 respectively,then which of the following is correct ?
QUESTION 4
In a Young’s double slit experiment the slit separation is 0.8mm and the interference patteren is obtained on a screen kept 50cm from the plane of the slits s1 and s2 . if the first bright fringes is formed 0.4mm from the central maximum the wavelength of light used is
QUESTION 5
Consider the effect on the angular separation of the fringes in a Youngs double experiment due to the following operation (i) the screen is moved away from the plane of the slits (ii) the separation between the two slits is increased till fringes are observed