Q1
short answer
2 marks
(a) (i) Define impact parameter and distance of closest approach for an alpha-particle in Geiger-Marsden scattering experiment. (ii) What will be the value of the impact parameter for scattering angle (I) = 0 and (II) = 180?
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Q2
short answer
2 marks
Photoelectric emission occurs when a surface is irradiated with the radiation of frequency (i) v1, and (ii) v2. The maximum kinetic energy of the electrons emitted in the two cases are K and 2K respectively. Obtain the expression for the threshold frequency for the surface.
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Q2
short answer
2 marks
Briefly explain the working of a light emitting diode. Mention its two uses.
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Q3
short answer
2 marks
Explain the formation of depletion region in a p-n junction.
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Q4
long answer
3 marks
With the help of a circuit diagram, explain the working of a p-n junction diode as a full-wave rectifier. Also draw its input and output waveforms.
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Q5
long answer
3 marks
Find the ratio of the de Broglie wavelengths associated with an alpha particle and a proton, if both (a) have the same speeds, (b) have the same kinetic energy, (c) are accelerated through the same potential difference.
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Q6
short answer
What is the -particle in Geiger-Marsden scattering experiment?
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Q7
short answer
2 marks
What will be the value of the impact parameter for scattering angle (I) = 0 and (II) = 180 ?
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Q9
long answer
Depict the variation of the potential energy of a pair of nucleons with the separation between them.
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Q10
long answer
3 marks
Imagine the fission of a Fe 56/26 into two equal fragments of Al 28/13 nucleus. Is the fission energetically possible ? Justify your answer by working out Q value of the process. Given : m Fe 56/26 = 55.93494 u, m Al 28/13 = 27.98191 u.
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Q10
long answer
3 marks
A small bulb is placed at the bottom of a tank filled with water to a depth of 70 cm. Find the surface area of the water through which the light of the bulb can emerge. The refractive index of water is 4/3.
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Q11
long answer
Depict a plane electromagnetic wave propagating along the x-axis. Write the expressions for its oscillating electric and magnetic fields.
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Q11
long answer
3 marks
The refractive index of an equilateral triangular prism is sqrt(2). Calculate (a) minimum angle of deviation (b) critical angle for the prism.
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Q12
long answer
3 marks
Write three characteristics of electromagnetic waves.
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Q13
long answer
3 marks
Name the electromagnetic waves which are produced by the following : (i) Radioactive decays of nucleus (ii) Welding arcs (iii) Hot bodies. Write one use each of these waves.
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Q14
long answer
3 marks
Draw a labelled ray diagram showing the formation of an image by an astronomical refracting telescope in normal adjustment. Hence, obtain the expression for its magnifying power.
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Q15
long answer
3 marks
Light of wavelength is incident normally on a slit. (i) Depict the intensity distribution in the pattern observed. (ii) Obtain the expression for the first maximum from the central maximum.
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Q16
long answer
3 marks
Use the energy level diagram shown below to obtain the relation between three wavelengths 1, 2 and 3 emitted due to the transition of electron from the energy states C and B.
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English physicist Thomas Young explained the interference of light using the principle of superposition of waves. He observed the interference pattern on a screen through his experimental arrangement, now called Young's double-slit experiment. He illuminated two slits S1 and S2 with light coming from a slit S. This interference pattern is made of bright and dark bands. These types of bands are called fringes. The distance between two consecutive bright and dark fringes is called fringe width.
Q19
mcq
If the screen is moved towards the slits S1 and S2, the fringe width: (i) decreases, but intensity of bright fringe remains the same (ii) increases, but intensity of bright fringe decreases (iii) decreases, and intensity of bright fringe decreases (iv) and intensity both remain the same.
- A. decreases, but intensity of bright fringe remains the same
- B. increases, but intensity of bright fringe decreases
- C. decreases, and intensity of bright fringe decreases
- D. and intensity both remain the same
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Q20
mcq
When both slits S1 and S2 are replaced by two independent but identical sources: (i) the pattern will remain unchanged (ii) pattern intensity will decrease (iii) fringes will disappear (iv) intensity will increase
- A. the pattern will remain unchanged
- B. pattern intensity will decrease
- C. fringes will disappear
- D. intensity will increase
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Q21
short answer
Is the speed of light in glass independent of the colour of light ? Give reason.
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Q22
short answer
3 marks
The refractive index of an equilateral triangular prism kept in air is root 2. Calculate: (a) the angle of minimum deviation.
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Q23
short answer
The refractive index of an equilateral triangular prism kept in air is root 2. Calculate: (b) the critical angle for the prism.
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The British physicist Thomas Young explained the interference of light using the principle of superposition of waves. He observed the interference pattern on the screen, in his experimental set-up, known as Young's double slit experiment. The two slits S1 and S2 were illuminated by light from a slit S. The interference pattern consists of dark and bright bands of light. Such bands are called fringes. The distance between two consecutive bright and dark fringes is called fringe width.
Q24
mcq
1 mark
If the screen is moved closer to the plane of slits S1 and S2, then the fringe width :
- A. will decrease, but the intensity of bright fringe remains the same.
- B. will increase, but the intensity of bright fringe decreases.
- C. will decrease, but the intensity of bright fringe increases.
- D. and the intensity both remain the same.
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Q25
mcq
1 mark
What will happen to the pattern on the screen, when the two slits S1 and S2 are replaced by two independent but identical sources ?
- A. The intensity of pattern will increase
- B. The intensity of pattern will decrease
- C. The number of fringes will become double
- D. No pattern will be observed on the screen
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Q26
mcq
1 mark
Two sources of light are said to be coherent, when both emit light waves of :
- A. same amplitude and have a varying phase difference.
- B. same wavelength and a constant phase difference.
- C. different wavelengths and same intensity.
- D. different wavelengths and a constant phase difference.
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Q27
mcq
1 mark
The fringe width is beta. If the whole set-up is immersed in a liquid of refractive index n, then the new fringe width will be :
- A. beta/n
- B. beta * n
- C. beta
- D. 2 * beta
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Q28
mcq
1 mark
The total path difference between two waves meeting at points P1 and P2 on the screen are lambda/3 and 2 lambda respectively. Then :
- A. bright fringes are formed at both points.
- B. dark fringes are formed at both points.
- C. a bright fringe is formed at P1 and a dark fringe is formed at P2.
- D. a bright fringe is formed at P2 and a dark fringe is formed at P1.
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