## Tuesday, August 2, 2011

### I MID TERM EXPECTED QUESTIONS .LESSONS 1,2,7,& 8 ( 5 MARKS)

5 MARKS
LESSONS 1 AND 2

78. A parallel plate capacitor has plates of area 200 cm and separation between the plates is 1 m m.  Calculate (i) the potential difference between the plates if 1 n C charge is given to the capacitor.  (ii)With the same charge (1nC) if the plate separation is increased to 2 mm , what is the new potential difference and (iii) the electric field between the plates?  (March 06)
79. Three capacitors each of capacitance 9 pF are connected in series.  (i) What is the total capacitance of the combination?  (ii) What is the potential difference across each capacitor if the combination is connected to 120 V supply?  (June 06, Oct 06)
80. Write the properties of lines of forces.  (Mar 07, Oct 07, Mar 08, 10)
81. Two capacitors of capacitances 0.5   F and 0.75   F are connected in parallel and the combination to a 110 V battery.  Calculate the charge from the source and charge on each capacitor.  (June 07)
82. Two positive charges of 12  C and 18  C respectively are 10 cm apart.  Find the work  done in bringing them 4 cm closer, so that they are 6 cm apart. (June 08)
83. Two capacitors of unknown capacitances are connected in series and parallel.  If the net capacitances in the two combinations are 6  F and 25  F repectively, find their capacitances.  (Oct 08)
84. Define electric potential at a point obtain an expression for electric potential due to a point charge.  (March 09)
85. The plates of a parallel plate capacitor have an area of 90 cm each and are separated by 2.5 mm.  The capacitor is charged by connecting it to a 400 V supply.  How much electrostatic energy is stored by the capacitor? (June 09)
86. What is electrostatic potential energy of a system of two point charges? (Oct 09)
87. Deduce an expression for the capacitance of a parallel plate capacitor.  (June 10)
88. Derive an empression for the torque experienced by an electric dipole when placed in a uniform electric field.  (Oct 10)

CURRENT ELECTRICITY

89. Define mobility.  Establish a relation between drift velocity and current. (March 06)
90. Obtain the condition for bridge balance in Wheatstones bridge.  (Mar 06, June 06, Oct 06, Mar 08, June 09, March 10)
91. State and verify Faraday’s second law of electrolysis.  (June 06, March 08)
92. If two or more resistors are connected in parallel, derive an expression for the effective resistance.  (Oct 06)
93. How will you compare the e.m.f.s of two cells using a potentiometer?  (March 07, Oct; 10)
94. a) In the given network, calculate the effective resistance between points  A & B.(March 07)
b) The effective resistances are 10 ohm, 2.4 ohm when they are connected in series and parallel respectively.  What are the resistances of individual resistors?
95. Explain the working of a Leclanche cell with a diagram.  (June 07)
96. State the explain Kirchhoff’s second law for electrical network.  (June 07)
97. Explain the principle of a potentiometer.  (Oct 07)
98. Explain the action of lead-acid accumulator.  (Oct 07)
99. Explain the determination of the internal resistance of a cell using voltmeter.  (June 08, Oct 09)
100. A copper wire of 10 m area of area of cross-section, carries a current of 2A.  If the number of electrons per cubic metre is 8x10 calculate the current density and overage drift velocity (Given e=1.6x10 C) (march 09)
101. State Faraday’s first law of electrolysis and describe the experimental verification.  (June 08, Oct 09)
102. Write any five applications of superconductors.  (Oct 08, March 09)
103. Explain the construction and working of Daniel cell.  (Oct 08, June 09, June 10)
104. The effective resistances are 10 ohm and 2.4ohm when two resistors are connected in series and in parallel.  What are the resistance of individual resistors?  (March 07, 10)
105. a) Three resistors are connected is series with 10 V supply as shown in the figure.  (June 10)
b) Find the voltage drop across each resistor.
(or)
b) What is the drift velocity of an electron in a copper conductor having area carrying a current of 2 A.   Assume that there are 10x10 electrons/m.
106. a) Find the current flowing across three resistors 3 ohm 5 ohm and 2 ohm  connected in parallel to a 15 V supply.  Also find the effective resistance and total current drawn from the supply.   (or)  (Oct 10)
b). In a metre  bridge, the balancing length for a 10 ohm resistance in left gap is 51.8 cm.  Find the unknown resistance and specific resistance of a wire of length 108 cm and radius 0.2 mm.
106. Applying Wheatstone’s network principle obtain the unknown resistance using metre bridge.