ELECTRICITY

1	The resistance of a wire does not depend on its (a) length (b) area of cross- section (c) shape (d) material	1
2	A cylindrical conductor of length ‘l’ and uniform area of cross section ‘A’ has resistance ‘R’. The area of cross section of another conductor of same material and the same resistance but of length ‘2l’ is (a) A/2 (b) 3A/2 (c) 2A (d) 3A	1
3	If four identical resistors, of resistance 8 ohm, are first connected in a series so as to give an effective resistance R_s, and then connected in parallel so as to give an effective resistance R_p, then the ration R_s/ R_p is (a) 32 (b) 2 (c) 0.5 (d) 16	1
4	Two LED bulbs of 12W and 6W are connected in series. If the current through 12W bulb is 0.06A the current through 6W bulb will be (a) 0.04 A (b) 0.06 A (c) 0.08 A (d) 0.12 A	1
5	A complete circuit is left on for several minutes, causing the connecting wire to become hot. As the temperature of the wire increases, the electrical resistance of the wire (a) decreases (b) remains the same (c) increases (d) increases for some time and then decreases	1
6	When the lightening strikes, 100C of charge flow in 0.02s. What is the current? (a) 0.2 A (b) 200 A (c) 0.05 A (d) 5000 A	1
7	Which device maintains a potential difference across a conductor? (a) cell or battery eliminator (b) ammeter (c) voltmeter (d) none of these	1

ASSERTION AND REASON QUESTIONS

(a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

(b) Both Assertion (A) and Reason (R) are true and Reason (R) is not the correct explanation of the Assertion (A).

(c) Assertion (A) is true, and Reason (R) is false.

(d) Assertion (A) is false, and Reason (R) True.

8	ASSERTION (A): Fuse wire must have high resistance and low melting point. REASON (R): Fuse is used for small current flow only.	1
9	ASSERTION (A): Electron has a negative charge. REASON (R): Electrons always move from a region of higher potential to a region of lower potential.	1
10	ASSERTION (A): Electrons move from lower potential to higher potential in a conductor. REASON (R): A dry cell maintains electric potential difference across the ends of a conductor.	1
11	ASSERTION (A): Alloys are commonly used in electrical heating devices like electric iron and heater. REASON (R): Resistivity of an alloy is generally higher than that of its constituent metals but the alloys have low melting points then their constituent metals.	1

VERY SHORT ANSWER QUESTIONS

12	Let the resistance of an electrical device remain constant, while the potential difference across its two ends decrease to one fourth of its initial value. What change will occur in the current through it? State the law which helps us in solving the above stated question.	2
13	The filament of an electric lamp draws a current of 0.5 A, which lights for 2 hours. Calculate the charge that flows through the circuit.	2
14	(i) List the factors on which the resistance of a conductor depends. (ii) Write the SI unit of resistivity.	2
15	An electric heater rated 1100 W operates at 220 V. Calculate (i) its resistance, and (ii) the current drawn by it.	2
16	Show how you would connect three resistors each of resistance 6Ω, so that the combination has a resistance of 9 Ω. Also justify your answer.	2

SHORT ANSWER TYPE QUESTIONS

17	(a) State Ohm's Law. Represent it mathematically. (b) Define 1 ohm. (c) What is the resistance of a conductor through which a current of 0.5 A flows when a potential difference of 2 V is applied across its ends?	3
18	(a) List the factors on which the resistance of a uniform cylindrical conductor of a given material depends. (b) The resistance of a wire of 0.01 cm radius is 10 Ω. If the resistivity of the wire is 50 × 10 ^{- 8} Ω m , find the length of this wire.	3
19	a) Write the mathematical expression for Joule's law of heating. (b) Compute the heat generated while transferring 96000 coulomb of charge in two hours through a potential difference of 40 V.	3
20	(a) Why is tungsten used for making bulb filaments of incandescent lamps? (b) Name any two electric devices based on heating effect of electric current.	3
21	(a) What is the meaning of electric power of an electrical device? Write its Sl unit. (b) An electric kettle of 2 kW is used for 2 h. Calculate the energy consumed in (i) kilowatt hour and (ii) joules	3
22	An electric motor rated 1100 W is connected to 220 V mains. Find: (i) The current drawn from the mains, (ii) Electric energy consumed if the motor is used for 5 hours daily for 6 days. (iii) Total cost of energy consumed if the rate of one unit is 5.	3
23	(i) State the law that explains the heating effect of current with respect to the measurable properties in an electrical circuit. (ii) List the factors on which the resistance of a conductor depends.	3

LONG ANSWER TYPE QUESTIONS

24	(a) Define electric power and state its SI unit. The commercial unit of electrical energy is known as 'unit. Write the relation between this 'unit' and joule. (b) In a house, 2 bulbs of 50 W each are used for 6 hours daily and an electric geyser of 1 kW is used for 1 hour daily. Calculate the total energy consumed in a month of 30 days and its cost at the rate of 8.00 per kWh.	5
25	(a) An electric bulb is rated at 200 V; 100 W. What is its resistance? (b) Calculate the energy consumed by 3 such bulbs if they glow continuously for 10 hours for complete month of November. (c) Calculate the total cost if the rate is₹ 6.50 per unit.	5
26	Draw a schematic diagram of a circuit consisting of a battery of 3 cells of 2 V each, a combination of three resistors of 10 Ω, 20 Ω and 30 Ω connected in parallel, a plug key and an ammeter, all connected in series. Use this circuit to find the value of the following: (a) Current through each resistor (b) Total current in the circuit (c) Total effective resistance of the circuit.	5
27	(a) State ohm’s law. (b) For the series combination of three resistors establish the relation R = R1 + R2 + R3 where the symbols have their usual meanings. Calculate the equivalent resistance of the combination of three resistors of 6 2, 9 2 and 18 Ω joined in parallel.	5
28	(i) Write the relation between resistance R and electrical resistivity p of the material of a conductor in the shape of cylinder of length I and area of cross-section A. Hence derive the SI unit of electrical resistivity. (ii) The resistance of a metal wire of length 3 m is 60 Ω. If the area of cross-section of the wire is 4 x 10^-7 m², calculate the electrical resistivity of the wire. (iii) State how would electrical resistivity be affected if the wire (of part 'ii') is stretched so that its length is doubled. Justify your answer.	5

CASE BASED STUDY QUESTIONS

Read the passage carefully and answer the following questions:

Electricians connect household circuits in parallel. A student observed that in his home, the TV, refrigerator, and lights all work independently, even when one appliance is switched off.

1. Why are household appliances connected in parallel and not in series?

2. If a refrigerator is rated 400 W and works for 5 hours daily, calculate the energy consumed in kWh in 7 days.

3. A 10 A fuse is connected in the main line of the household. Explain what happens if the current exceeds 10 A.

4. State two advantages of parallel connections in household wiring.

Read the passage carefully and answer the following questions:

A student performs an experiment to study Ohm’s law by plotting a graph between potential difference (V) and current (I). He obtained a straight line passing through the origin.

1. What does the straight-line graph signify?

2. If the resistance of the conductor is 5 Ω, calculate the current when potential difference is 10 V.

3. Name the law that relates V, I, and R.

4. Why should the connections in this experiment be tight and clean?

DOWNLAOD THE ASSIGNMENT HERE:

FOLLOW THE INSTRUCTIONS FOR DOWNLOAD THIS ASSIGNMENT:

1. SEARCH WWW.SCIENCEARENA.IN

2. OPEN EDUCATION AND RESOURCES IN MENU BAR.

3. SINGLE CLICK DOWNLOAD AVAILABLE IN DOWNLAOD SECTION.

https://www.sciencearena.in/p/education-resources.html

DOWNLAOD THE ASSIGNMENT HERE:

https://www.sciencearena.in/p/education-resources.html