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**CHAPTER-12 ELECTRICITY **

VERY SHORT ANSWER QUESTIONS

CARRYING 1 MARK WITH ANSWER

**Q1: What is represented by joule/coulomb?**

Answer: It represents potential difference.

**Q2: A charge of 2C moves between two plates, maintained at a p.d of 1V. What is the energy acquired by the charge?**

Answer: W=QV=2×1=2J

**Q3: Why are copper wires used as connecting wires?**

Answer: The electrical resistivity of copper is low

**Q4: A wire of resistivity 10 ohm meter is stretched to double its length. What is its new resistivity?**

Answer: It remains same because resistivity depends on nature of material.

**Q5: What is the resistance of connecting wire?**

Answer: The resistance of a connecting wire, which is made of good conductor, is negligible.

**Q6: What should be the resistance of an ammeter?**

Answer: The resistance of an ammeter should be very small and for an ideal ammeter, its value is zero.

**Q7: What should be the resistance of a Voltmeter?**

Answer: The resistance of a voltmeter should be very high and for an ideal voltmeter, its value is infinity.

**Q8: Which has more resistance: 100W bulb or 60W bulb?**

Answer: As R is inversely proportional to P for constant V. Thus, the resistance of 60W bulb is more.

**Q9: How will you join three resistances, each of 2 ohm so that the effective resistance is 3 ohm?**

Answer: A parallel combination of two resistances (which will be 1 ohm) joined in series with the third resistance (2 ohm)

**Q10: What happens to the current in a circuit if its resistance is doubled?**

Answer: As I inversely proportional to R, the current is reduced to half of its previous value.

**Q11: What happens to the resistance of a circuit if the current through it is doubled?**

Answer: The resistance of the circuit does not depend on the current through it, it will remain the same.

**Q12: How does the resistance of a wire depend upon its radius?**

Answer: As R is inversely proportional to A, R is inversely proportional to square of radius r.

**Q13: Two wires are of the same length, same radius, but one of them is of copper and the other is of iron. Which will have more resistance?**

Answer: A and l are same R depends only on resistivity and it is more for iron so iron has more resistance.

**Q14: Two wires of same material and same length have radii r1 and r2. Compare their resistances.**

Answer: R inversely proportional to square of radius r.

R1/R2 =(r2/r1)²

**Q.15 Given n resistors each of resistors Rs. How will you combine them to get the**

**(i) maximum and**

**(ii) minimum effective resistance?**

**What is the ratio of the maximum to minimum resistance?**

Answer: For maximum resistance Rs= nr (Equivalent of series combination)

For minimum resistance Rp= r/n (Equivalent of parallel combination)

Rs/Rp= n2

**☛See also:**

Ch 12 - Electricity (Q & A, NCERT Solutions and Numerical)

Ch 12 - Electricity (MCQs)

Ch 12 - Electricity (Worksheet)

Ch 12 - Electricity (Important Points To Remember)

Ch 12 - Electricity (Holiday Assignment)

Ch 12 - Electricity (Assignment)

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