Short Answer TypeAn electric dipole of dipole moment p is placed in a uniform electric field E with its axis inclined to the field. Write an expression for the torque 
experienced by the dipole in vector form. Show diagrammatically how the dipole should be kept in the electric field so that torque acting on it is:
i) maximum
ii) zero
You are provided with 8 
capacitors. Show with the help of a diagram how you will arrange minimum number of them to get a resultant capacitance of 20 
.
i) Define temperature coefficient of resistance of the material of a conductor.
ii) When the cold junction of a thermocouple is maintained at 0o C, the thermo emf 'e', generated by this thermocouple is given by the relation,
,
where 
is the temperature of the hot junction in oC. Find the neutral temperature of the thermocouple.
Draw a labelled circuit diagram of a potentiometer to compare emf of two cells. Write the working formula.
b) How much resistance should be connected to 15-ohm resistor shown in the circuit in figure below so that the points M and N are at the same potential.
i) With reference to the free electron theory of conductivity, explain the terms:
1. Drift speed
2. Relaxation time
ii) What is the colour code of a carbon resistor having a resistance of 470 ohm and a tolerance of 5%.
i) State Tangent Law in Magnetism.
ii) At a certain temperature, a ferromagnetic material becomes paramagnetic. What is the temperature called?
i) State Biot Savart Law.
ii) Find magnetic flux density at a point on the axis of a long solenoid having 5000 turns/m when it is carrying a current of 2 A.
i) Biot Savart Law:
The magnitude of the field at point P is given by,
dB = 
;
where 
is the angle between i dl and r.
ii) Number of turns per metre = 5000 turns/m
Current, I = 5 A
Flux density, B = 
= 
= 
= 0.0126 T
Name the part of the electromagnetic spectrum which is,
i) suitable for radar systems used in aircraft navigation
ii) Produced by bombarding a metal target with high speed electrons
In Young's double slit experiment, using monochromatic light, fringes are obtained on a screen placed at some distances from the slits. If the the screen is moved by 5 x 10-2 m towards the slits, the change in the fringe width is 3 x 10-15 m. If the distance between the two slits is 10-3 m, calculate the wavelength of the light used.
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