With the help of a suitable example and an equation, explain the

Subject

Physics

Class

ICSE Class 12

Pre Boards

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Sample Papers

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 Multiple Choice QuestionsShort Answer Type

41.

Find the minimum wavelength of the emitted X-rays, when an X-ray tube is operated at 50 kV.

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42.

i) Define half-life of a radioactive substance.

ii) Using the equation, N = No e-straight lambdat, obtain the relation between half-life (T) and decay constant (straight lambda right parenthesis of a radioactive substance.

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43.

With the help of a suitable example and an equation, explain the term pair production.


Pair production: When an energetic gamma ray photon falls on a heavy substance, it is absorbed by some nucleus of the substance and its  energy gives rise to the production of an electron and a positron. This phenomenon, in which energy is converted into mass, is called pair- production.

straight gamma space photon space equals space stack straight beta presubscript negative 1 end presubscript superscript 0 with left parenthesis electron right parenthesis below space space space space plus space space space stack straight beta presubscript plus 1 end presubscript superscript 0 with left parenthesis positron right parenthesis below
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44.

Draw a labelled diagram of a full wave rectifier. Show how output voltage varies with time, if input voltage is a sinusoidal voltage.

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45.

What is a NAND gate? Write it's truth table?

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 Multiple Choice QuestionsLong Answer Type

46.

Derive an expression for intensity of electric field at a point in broadside position or on an equatorial line of an electric dipole.

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47.

Figure below shows a capacitor C, an inductor L and resistor R, connected in series to an ac supply of 220 V.


Calculate:

i) the resonant frequency of the given LCR circuit

ii) current flowing through the circuit

iii) Average power consumed by the circuit.

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48.

On the basis of Huygen's wave theory of light, show that the angle of reflection is equal to the angle of incidence. You must draw a labelled diagram for this deviation.

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