(i) Write an expression for Biot-Savart’s law in the vector fo

Subject

Physics

Class

ICSE Class 12

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 Multiple Choice QuestionsShort Answer Type

41. The following equation represents a fusion reaction :

straight H presubscript 1 presuperscript 2 space plus space straight H presubscript 1 presuperscript 3 space rightwards arrow space He presubscript 2 presuperscript 4 space plus space straight n presubscript 0 presuperscript 1 space plus space straight Q space semicolon

space where space straight Q space is space the space enrgy space released

Mass space of space straight H presubscript 1 presuperscript 2 space space atom space equals space 2.014102 space straight u

Mass space of space straight H presubscript 1 presuperscript 3 space atom space equals space 3.016050 space straight u

Mass space of space He presubscript 2 presuperscript 4 space atom space equals space 4.002603 space straight u

Mass space of space space neutron space space straight n presubscript 0 presuperscript 1 space equals space 1.008665 space straight u

Calculate the value of Q.

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42. What is a Zener diode? Explain how it can be used to stabilise the voltage in a circuit.
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43. The output of an OR gate is connected to the input of a NOT gate. Draw the logic circuit of this combination and write its truth table.  
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 Multiple Choice QuestionsLong Answer Type

44.

The current flowing through a conductor is given by I = neAvd

(i) Identify each term in the equation.

(ii) Obtain an expression for vd, if the current flowing through the conductor of length I has its ends maintained at a potential difference of V volts.

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45.

(i) Write an expression for Biot-Savart’s law in the vector form. Write an expression for the magnetic field at the centre of a circular coil of radius R, with N turns and carrying a current I. 

(ii) A helium nucleus completes one round of a circle of radius 0.8 m in 2 seconds. Find the magnetic field at the centre of the circle.


Expression for Biot-Savart’s Law in the vector form,


Error converting from MathML to accessible text. 
So, for N turns, 


open vertical bar straight B with rightwards harpoon with barb upwards on top close vertical bar space equals space fraction numerator mu subscript o space I space N over denominator 2 r end fraction 
The direction of B is perpendicular to the plane of the coil directed outward.

ii) As,

 straight B with rightwards harpoon with barb upwards on top space equals space fraction numerator mu subscript o space I over denominator 2 r end fraction space equals space fraction numerator mu subscript o q over denominator 2 r t end fraction space

Here,

q = Charge on 2 electrons

   = 2 x 1.6 x 10-19 C

   = 3.2 x 10-19 C.

t = 2 seconds.

r = 0.8 m

B = fraction numerator 4 straight pi space straight x space 10 to the power of negative 7 end exponent space straight x space 3.2 space straight x space 10 to the power of negative 19 end exponent over denominator 2 space straight x space 0.8 space straight x space 2 end fraction 

   = 4π x 10-26 


   = 4 x 3.14 x 10-26 

   = 1256 x 10-25



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46. Show that straight I subscript rms space equals space fraction numerator straight I subscript straight o over denominator square root of 2 end fraction where Irms is the root mean square value of alternating current and I0 is its peak value.
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47.

(i) Derive an expression for the fringe width ‘y’ in Young’s double slit experiment. Use X as the wavelength of the monochromatic source, D as the distance of the screen from the slits and d as the distance of separation between the slits.

(ii) How does the fringe pattern change if the monochromatic source of light in the above experiment is replaced by a white source of light ?

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