Physics solution ch.electricity

Class X Chapter 12 – Electricity Science Page 1 of 27 Website: www.vidhyarjan.com Email: [email protected] Mobile: 9999 249717 Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051 (One Km from ‘Welcome Metro Station) Question 1: What does an electric circuit mean? Answer: An electric circuit consists of electric devices, switching devices, source of electricity, etc. that are connected by conducting wires. Question 2: Define the unit of current. Answer: The unit of electric current is ampere (A). 1 A is defined as the flow of 1 C of charge through a wire in 1 s. Question 3: Calculate the number of electrons constituting one coulomb of charge. Answer: One electron possesses a charge of 1.6 × 10−19 C, i.e., 1.6 × 10−19 C of charge is contained in 1 electron. ∴ 1 C of charge is contained in Therefore, electrons constitute one coulomb of charge. Class X Chapter 12 – Electricity Science Page 2 of 27 Website: www.vidhyarjan.com Email: [email protected] Mobile: 9999 249717 Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051 (One Km from ‘Welcome Metro Station) Question 1: Name a device that helps to maintain a potential difference across a conductor. Answer: A source of electricity such as cell, battery, power supply, etc. helps to maintain a potential difference across a conductor. Question 2: What is meant by saying that the potential difference between two points is 1 V? Answer: If 1 J of work is required to move a charge of amount 1 C from one point to another, then it is said that the potential difference between the two points is 1 V. Question 3: How much energy is given to each coulomb of charge passing through a 6 V battery? Answer: The energy given to each coulomb of charge is equal to the amount of work required to move it. The amount of work is given by the expression, Potential difference = Where, Charge = 1 C Potential difference = 6 V Therefore, 6 J of energy is given to each coulomb of charge passing through a battery of 6 V. Question 1: On what factors does the resistance of a conductor depend? Answer: The resistance of a conductor depends upon the following factors: (a) Length of the conductor (b) Cross-sectional area of the conductor (c) Material of the conductor (d) Temperature of the conductor Question 2: Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why? Answer: Resistance of a wire, Where, = Resistivity of the material of the wire l = Length of the wire A = Area of cross-section of the wire Resistance is inversely proportional to the area of cross-section of the wire. Thicker the wire, lower is the resistance of the wire and vice-versa. Therefore, current can flow more easily through a thick wire than a thin wire. Question 3: Let the resistance of an electrical component remains constant while the potential difference across the two ends of the component decreases to half of its former value. What change will occur in the current through it? Answer: The change in the current flowing through the component is given by Ohm’s law as, V = IR Where, Resistance of the electrical component = R