﻿ i) What is Compton effect ? (ii) In Coolidge X-Ray tube (Modern

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## ISC Class 12 Physics Solved Question Paper 2012

41. Energy levels of H atom are given by:

E where n is Principal Quantum number. Calculate the wavelength of electromagnetic radiation emitted by hydrogen atom resulting from the transition: n = 2 to n = 1.
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# 42.i) What is Compton effect ?(ii) In Coolidge X-Ray tube (Modern X-Ray tube) how will you vary:(1) intensity of emitted X-Rays?(2) penetrating power of emitted X-Rays?

(i) Compton effect is the phenomenon due to which wavelength of radiation scattered by an element is slightly greater than that of the incident radiation.

(ii) Intensity of emitted x-ray is increased by increasing the current flowing through the filament.

(2) Penetrating power of X-ray is increased by increasing the p.d between cathode and anticathode.

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43. Complete the following table for a radioactive element whose half life is 5 minutes. Assume that you have 32 g of this element at start, i.e. at t = 0.

Now, using this data, plot the “decay curve”.

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44. Calculate the energy released when an electron annihilates a positron.
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45. Draw a labelled energy band diagram for a solid which is an insulator. What is the main difference between this diagram and that of a semiconductor?
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46. Figure below shows the circuit of an electronic device:

(i) Which electronic device: a rectifier, an amplifier or an oscillator does the above circuit represent?

(ii) State where the input voltage is applied and where the output voltage is available.

(iii) Compare the output voltage of this circuit with its input voltage.

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47. Prepare a truth table for the combination of gates shown in Figure 8 below:

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