Q1. Why closed path is required for the flow of current?
Q2. What causes the potential difference between the two terminals of a cell?
Q3. A wire of resistivity is pulled to double its length. What will be its new resistivity?
Q4. In how much time will a bulb of 100 W consume an energy of 2 kWh?
Q5. How does the resistance of an ohmic conductor depend on the applied voltage?
Q6. What happens to the other bulbs in a series circuit, if one bulb blows off?
Q7. What is meant by potential difference between two points?
Q8. Name the device that helps to maintain a potential difference across a conductor.
Q9. State the relationship between 1 ampere and 1 coulomb.
Q10. A charge of 150 coulomb flows through a wire in one minute. Find the electric current flowing through it.
Q11. A given length of a wire is doubled and this process is repeated once again. By what factor does the resistance of the wire changes?
Q12. The resistance of a resistor is kept constant and the potential difference across its two ends is decreased to half of its former value. State the change that will occur in the current through it.
Q13. Calculate the number of electrons constituting one coulomb of charge. (Charge on 1 electron = 1·6 × 10-19 C)
Q14. Write SI unit of resistivity.
Q15. Name the instrument used for measuring
(i) Potential difference
Q16. Which is having more resistance – a 220 V, 100 W bulb or a 220 V, 60 W bulb.
Q17. Nichrome is used to make the element of electric heater. Why?
Q18. Electric fuse is an important component of all domestic circuits. Why?
Q19. You are given three bulbs of 40 W, 60 Wand 100 W. Which of them has lower resistance?
Direction (Q. No. 20- 24) In each of the following questions, a statement of Assertion is given by the corresponding statement of Reason. Of the statements, mark the correct answer as
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
(c) If Assertion is true, but Reason is false.
(d) If Assertion is false, but Reason is true.
(e) If Assertion and Reason both are false.
Q20. Assertion: The connecting wires are made of copper.
Reason: The electrical conductivity of copper is high.
Q21. Assertion: Resistors connected in series are more effective than those connected in parallel.
Reason: Resistance of resistors increase when connected in series.
Q22. Assertion: Domestic circuits are connected in Parallel.
Reason: Parallel circuits have same current in every part of the circuit.
Q23. Assertion: Two wires of same length and material have different areas of the cross-section.
Reason: The wire with the lower area of cross-section has the lower resistivity.
Q24. Assertion: Nichrome is used in making of heater rods.
Reason: Nichrome has high resistivity.
Q25. How much work is done in moving a charge of 2 C from a point of 118V to a point of 128V?
(d) 10 J
Q26. Which of the following terms does not represent electric power in a circuit?
(d) V2 /R
Q26. What is the minimum resistance which can be made using five resistors each of 1/5Q?
(a) 1/5 Q
(b) 1/25 Q
(c) 1/10 Q
(d) 25 Q
Q27. When a conducting wire is stretched to double of its initial length, then which property of conducting wire increases?