ASSIGNMENT FOR CLASS - 10th (ELECTRICITY)

 

 NUMERICALS ON ELECTRICITY 

1. An electric bulb draws a current of 8 A and works on 250 V on the average 8 hours a day.

a. Find the power consumed by the bulb 

b. If the electric distribution company changes Rs 5 for 6 KWH, what is the monthly bill for 60 days.

2. A wire of length 3 m and area of cross-section 1.7 × 10-6 m2 has a resistance 3 × 10-2 ohm.

a. What is the formula for resistivity of the wire and what is the unit of it 

b. Calculate the resistivity of the wire

3. How can three resistors of resistances 2 Ω, 3 Ω and 6Ω be connected to give a total resistance of (a) 4 Ω, (b) 1 Ω?

4. What is (a) the highest, (b) the lowest total resistance that can be secured by combinations of four coils of resistances 4 Ω, 8 Ω, 12 Ω, 24 Ω?

5. An electric motor takes 5 A from a 220 V line. Determine the power of the motor and the energy        consumed in 2 h.      

6.(a) Define electric power. Express it in terms of potential difference V and resistance R. 

  (b) An electrical fuse is rated at 2 A. What is meant by this statement? (c) An electric iron of 1 kW is     operated at 220 V. Find which of the following fuses that respectively rated at 1 A,3 A and 5 A can be  used in it. 

7. The figure below shows three cylindrical copper conductors along with their face areas and lengths. Discuss in which geometrical shape the resistance will be highest. 

8. How much current will an electric bulb draw from 220 V source if the resistance of the bulb is 1200Ω? If in place of bulb, a heater of resistance 100 Ω is connected to the sources, calculate the current drawn by it.