- Introduction
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- Electric Charges
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- Conductors and insulators
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- Electric potential and potential difference
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- Electric current and electrical circuits
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- Circuit Diagrams
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- Ohm's Law
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- Factors affecting of resistances of a conductor
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- Resistance of a system of resistors
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- Heating Effect of current
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- Applications of heating effect of current
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- Electric Power

- Electric Charge
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- Electric Potential
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- Materials(conductors, insulators & superconductors)
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- Electric Current
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- Ohm's Law

**Question 1.** State Ohm’s law. How can it be verified experimentally? Does it hold good in all conditions? Comment.

**Question 2.** Express Joule’s law of heating mathematically.

**Question 3.**What is the resistance of 12 m wire having radius 2×10^{-4} m and resistivity 3.14×10^{-8} Ω-m.

**Question 4.** A 4Ω resistance wire is doubled on it. Calculate the new resistance of the wire.

**Question 5.** An electric iron consumer’s energy at a rate of 840 W when heating is at the maximum rate and 360 W when the heating is at the minimum.
The voltage is 220 V. What are the current and the resistance in each case?

**Question 6.** Define 1 volt. Express it in terms of SI unit of work and charge.
Calculate the amount of energy consumed in carrying a charge of 1 coulomb through a battery of 3 volts.

**Question 7.** Write symbols of the following circuit elements:

(i) Battery (ii) Ammeter (iii) Voltmeter

State the role of these elements in an electric circuit.

**Question 8.** What is meant by “electrical resistance” of a conductor? State how resistance of a conductor is affected when

(i) a low current passes through it for a short duration

(ii) a heavy current passes through it for about 30 seconds.

**Question 9.** How do we connect ammeter and voltmeter in an electric circuit? Draw a circuit diagram to justify your answer. What is likely to happen if the positions of these
instruments are interchanged? Give reason.

**Question 10.** A student has a resistance wire of 1 ohm. If the length of this wire is 50 cm, to what length he should stretch it uniformly so as to obtain a wire of 4 Ω
resistance? Justify your answer.

**Question 11.** Calculate the resistivity of the material of a wire of length 1 m, radius 0.01 cm and of resistance 20 ohms.

**Question 12.** The resistance per meter length of a wire is 10 Ω. If the resistivity of the material of the wire is 50×10^{-8} ohm meters, find the area of cross – section of the wire.

**Question 13.** The resistance of a wire of 0.01 cm radius is 10 Ω. If the resistivity of the material of the wire is 50×10^{-8} ohm meters, find the length of the wire.

**Question 14.** Show different ways in which three resistance of R ohm each may be connected in a circuit. In which case is the equivalent resistance of the combination:

(i) maximum (ii) minimum

**Question 15.** Three resistors of 1 Ω, 2 Ω and 3 Ω are connected in parallel in a circuit. If 1 Ω resistor draw a current of 1 A, find the current through the other two resistors.

**Question 16.** When a resistor R is connected to a battery of 3 V, it draws a current of 1 ampere. find the value of R. If an identical resistor is connected in parallel with it, find the current that flows through the circuit.

**Question 17.** Derive an expression for the equivalent resistance of three resistors R_{1}, R_{2} and R_{3} connected in parallel.

In a conductor electrons are flowing from B to A. What is the direction of conventional current? Give justification for your answer.

A steady current of 1 ampere flows through a conductor. Calculate the number of electrons that flow through any section of the conductor in 1 second. (Charge on electron = 1.6×10

(i) An electric cell (ii) open plug key (iii) Wires crossing without connection

(iv) Variable resistor (v) Battery (vi) Electric bulb

(vii) Resistance (viii) Wire joint

(b) Represent it (Ohm’s law) mathematically.

(c) Draw a circuit diagram for the verification of Ohm’s law.

(d) Draw the V - I graph for this (Ohm’s) law.

(i) its length is doubled, (ii) its radius is doubled?

**Answer**

(3) 3 Ω

(4) 1 Ω

(5) 134.2 Ω

(10) 200 cm

(11) 8.1 Ω

(12) A = 5×10^{-6} m^{2}

(15) 0.33 A

(16) 4.5 A

(20) R_{p} = 1Ω

(25) 10 J

(28) 7 Ω

(32) 36 Ω

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