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CBSE Notes 2011-2012

Imortent Question for Xth Electicity

Electricity

  1. Two students perform the experiments on series and parallel combination of two given resisters R1 and R2 and plot the following V-I graphs. This of the two graphs correctly represents the labels ‘series and parallel’. Justify your answer.
  2. Two metallic wires A and B of the same material are connected in parallel. Wire A has length l and radius r. wire B has length 2l and radius 2r. Calculate the ratio of the equivalent resistance in parallel combination and the resistance of the wire A.
  3. You are given two resistors of 5? and 20?, a battery of emf 2.5 V, a key and an ammeter. Draw a circuit diagram of all given components such that ammeter gives a reading of 0.1 A.
  4. The electrical resistivity of few materials is given below in ?m. Which one of these materials has the highest electrical conductivity and which has the lowest?

A (6.84x10-8), 
B (1.60x10-8), 
C (1.00x10-4),
D (2.50x1012),
E(4.40x10-5)
and F (2.30x1017).

  1. A piece of wire of resistance 20? is drawn out so that its length is increased to twice its original length. Calculate the resistance of the wire in the new situation.
  2. Two resistors with resistances

(i) 5 ? and 10 ?
(ii) 10 ? and 15 ?
respectively are to be connected to a battery of emf
(i) 6 V,
(ii) 12 V so as to obtain
a) minimum current flowing,
b) maximum current flowing.
a. How will you connect these resistances in each coil?
b. Calculate the strength of total current in the circuit in the two cases.
 

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