An alternating emf of 110 V is applied to a circuit containing a

Subject

Physics

Class

ICSE Class 12

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 Multiple Choice QuestionsShort Answer Type

41.

Voltage applied between cathode and anode of an X-ray tube is 18 kV. Calculate the minimum wavelength of the X-rays produced.

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42.

In a nuclear reactor, what is the function of:

i) The moderator

ii) The control rods

iii) The coolant

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43.

The atomic mass of Uranium straight U presubscript 92 presuperscript 238 is 238.0508 u, while that of thorium Th presubscript 90 presuperscript 234 is 234.0436 u, and that of Helium He presubscript 2 presuperscript 4 is 4.0026 u. Alpha decay converts straight U presubscript 92 presuperscript 238 and Th presubscript 90 presuperscript 234 as shown below.

straight U presubscript 92 presuperscript 238 space rightwards arrow space Th presubscript 90 presuperscript 234 space plus space He presubscript 2 presuperscript 4 space plus space energy
Determine the energy released in this reaction.

ii) What is a neutrino?

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44.

In semiconductor physics, what is meant by:

i) a rectifier
ii) an amplifier
iii) an oscillator

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 Multiple Choice QuestionsLong Answer Type

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45.

An alternating emf of 110 V is applied to a circuit containing a resistance R of 80 ohm and inductor L in series. The current is found to lag behind the supply voltage by an angle straight theta space equals space tan to the power of negative 1 end exponent open parentheses 3 over 4 close parentheses. Find the:
i) Inductive Reactance
ii) Impedence of the circuit
iii) Current flowing in the circuit
iv) If the inductor has a coefficient of self inductance of 0.1 H, what is the frequency of the applied emf


Alternating emf = 110 V
Resistance, R = 80 ohm
Inductor, L = ?

tan space theta space equals space 3 over 4
This implies, 

i)
     3 over 4 equals X subscript L over 80

rightwards double arrow space straight X subscript straight L space equals space 60 space straight capital omega, is the inductive reactance.

ii) Z2 = XL2 + R2

        = 602 + 802

Therefore, Z = 100 ohm, is the impedance of the circuit. 

iii) Current flowing in the circuit, I = straight V over straight Z = 110 over 100 space equals space 1.1 space A
iv) Self inductance, L = 0.1 H

Frequency of the applied emf, f = ?

We know that,

space space space space space space straight X subscript straight L space equals space 2 πfL

rightwards double arrow space 60 space equals space 2 space straight x space 3.14 space straight x space straight f space straight x space 0.1

therefore space straight f space equals space fraction numerator 60 over denominator 0.628 end fraction space equals space 95.5 space Hz

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46.

i) What is meant by the dispersive power of a transparent material?

ii) Show that, two thin lenses kept in contact, form an achromatic doublet if they satisfy the condition:

straight omega over straight f plus fraction numerator omega apostrophe over denominator f apostrophe end fraction space equals space 0
where the terms have their usual meanings.

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47.

With the help of a diagram, show how you can use several NAND gates to obtain an OR gate.

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