1) What happens to resistance when length of conductor is doubled without affecting the thickness of conductor?
2) What is the lowest resistance that can be obtained by combining four coils of resistors of 4 , 8 ?, 12 ? and 24 ??
3) What is an ammeter?
4) Calculate the number of electrons constituting one coulomb of charge.
5) A voltmeter is to be connected in the circuit to measure potential difference across a conductor. Mention the type of combination in which it should be conducted with the conductor.
6) A bulb cannot be used in place of a resistor to verify Ohm’s law. Jusify this statement with reason.
7) What is meant by electric resistance of a conductor?
8) Define resistance of a conductor.
9) Write SI unit of resistivity.
10) How does the resistivity of alloys compare with those of pure metals form which they may have formed?
11) Mention any two factors on which the resistance of a cylindrical conductor depends.
12) Write the relation between resistance R of filament of a bulb, its power (P) and a constant voltage V applied across it.
13) Power of a lamp is 100 W. Find the energy in joules consumed by it in 1 s.
14) When a 12 V battery is connected across an unknown resistor, 2.5 mA current flows in the circuit. Find the resistance of the resistor.
15) State the factors on which the resistance of a cylindrical conductor depends. Hence, define resistivity.
16) In an electric circuit with a resistance wire and a cell, the current flowing is I. What would happen to this current if the wire is replaced by another thicker wire of same material and same length. Give reason.
17) A wire of length L and resistance R is stretched so that the length is doubled and area of cross – section halved. How will (i) resistance change, and (ii) resistivity change?
18) (a) What material is used in making the filament of an electric bulb?
(b) Name the characteristics which make it suitable for this.
19) An electric lamp is marked 220 V, 100W. It is used for 5 hours daily. Calculate:
(a) Its resistance while glowing.
(b) Energy consumed in kW h/day.
20) List in a tabular form two differences between a voltmeter and an ammeter.
21) A thick wire and a thin wire the same material are successively connected to the same circuit to find their respective resistance. Which one will have lower resistance? Give reason.
22) State the factors on which the heat produced in a current carrying conductor depends. Give one practical application of this effect.
23) Write the relation between electric power (W) of a device with potential difference (Volt) across it and current (I) flowing through it.
24) What is electrical resistivity? In a series circuit comprising of a resistor having a metallic wire, the ammeter reads 5 A. The reading of the ammeter decrease to half when the length of the wire is doubled. Why?
2) R= 2 ?
4) 0.625 1019
13) 100 J
14) 4800 ?
19) a) 484 ?
b) 0.5 kW h
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