ICSE physics
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An 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
Expression for torque in the vector form is:
;
where,
p is the dipole moment, and
E is the electric field.
i) When torque acting is maximum, dipole should be placed perpendicular to the electric field.
ii) When torque acting is zero, dipole is placed parallel to the magnetic field.
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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 
.
Any two capacitors are connected in series and the othr two capacitors are connected in parallel.
. 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.
i) Temperature coefficient of resistance is defined as fractional increase in resistance per degree rise in temperature.
ii)
Draw a labelled circuit diagram of a potentiometer to compare emf of two cells. Write the working formula.
The potentiometer to compare EMFs of two cells is as shown below:
Working formula is given by,
E1 : E2 = l1 : l2
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.
For points M and N to be at the same potential, the resistance that should be connected to 15 ohm is:
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Mock Test Series
Mock Test Series