important questions from chapter electricity class 10
Answers
1. ..........=1 joule/1 second.
2. 1 kW.h =..........J.
3. Magnetic effect of electric current was discovered by.......... .
4. Electric motor converts electric energy into .......energy.
5. The device used for producing a current is called...... .
6. At the time of short circuit, the current in the circuit......... .
7. The direction of magnetic field around a straight conductor carrying is given by........ .
8. Electric generator (diagram).
9. Define electric power.
10. State the formula for electric power. Hence, obtain it's SI unite.
11. What is the commercial unit of electric energy? Obtain the relation between this unit and the SI unit of energy.
12. What is 1 kilowatt.hour?
13.what is heating effect of electric current? What is it's origin?
14. State joule's law about heating effect of electric current.
15. Obtain the mathematical expression for the heat generated in a metallic conductor by electric current (joule's law).
16. Name any six domestic appliances whose working is based on the heating effect of electric current
OR
State appliances of heating effect of electric current.
17. Explain the application of heating effect of electric current in an electric iron.
18. What does the electricity meter measure?
19. Explain the term short circuiting what does a short circuit lead to?
OR
How does the short circuit form? What is it's effect?
20. What is overloading? When does it occur? What does it cause? How can overloading be avoided?
21. Explain the application of heating effect of electric current in a fuse.
22. What is electromagnetic induction? Who discovered it?
23. State Faraday's law of induction.
24. State Fleming's right hand rule.
25. What is value of frequency of AC in india?
26. What is the periodic time of AC in India?
27. State one advantage of AC over DC.
28. Name two appliances/ devices in which an alternative current is used.
OR
State any two uses of an AC generator.
29. Explain the construction and working of an electric generator (AC). Draw a neat diagram and label it.
30. Draw the diagram of DC generator. Then explain as to how the DC current is obtained.
31. for electric power transmission, copper or aluminum wire is used.
32. Tungsten metal is used to make a solenoid type coil in an electric bulb.
33. Direact current and alternate current.
34. Electric motor and electric generator.
35. AC generator and DC generator.
Multiple Choice Questions
A cell, a resistor, a key and ammeter are arranged as shown in the circuit diagrams of Figure 12.1. The current recorded in the ammeter will be
(a) maximum in (i)
(b) maximum in (ii)
(c) maximum in (iii)
(d) the same in all the cases
In the following circuits (Figure 12.2), heat produced in the resistor or combination of resistors connected to a 12 V battery will be
(a) same in all the cases
(b) minimum in case (i)
(c) maximum in case (ii)
(d) maximum in case (iii)
Electrical resistivity of a given metallic wire depends upon
(a) its length
(b) its thickness
(c) its shape
(d) nature of the material
A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross section of the filament in 16 seconds would be roughly
(a) 1020
(b) 1016
(c) 1018
(d) 1023
Identify the circuit (Figure 12.3) in which the electrical components have been properly connected.
(a) (i)
(b) (ii)
(c) (iii)
(d) (iv)
What is the maximum resistance which can be made using five resistors each of 1/5 Ω?
(a) 1/5 Ω
(b) 10 Ω
(c) 5 Ω
(d) 1 Ω
What is the minimum resistance which can be made using five resistors each of 1/5 Ω?
(a) 1/5 Ω
(b) 1/25 Ω
(c) 1/10 Ω
(d) 25 Ω
The proper representation of series combination of cells (Figure 12.4) obtaining maximum potential is
(a) (i)
(b) (ii)
(c) (iii)
(d) (iv)
Which of the following represents voltage?
A cylindrical conductor of length l and uniform area of cross section A has resistance R. Another conductor of length 2l and resistance R of the same material has area of cross section
(a) A / 2
(b) 3A / 2
(c) 2A
(d) 3A
A student carries out an experiment and plots the V-I graph of three samples of nichrome wire with resistances R1, R2 and R3 respectively (Figure.12.5). Which of the following is true?
(a) R1 = R2 = R3
(b) R1 > R2 > R3
(c) R3 > R2 > R1
(d) R2 > R3 > R1
If the current I through a resistor is increased by 100% (assume that temperature remains unchanged), the increase in power dissipated will be
(a) 100 %
(b) 200 %
(c) 300 %
(d) 400 %
The resistivity does not change if
(a) the material is changed
(b) the temperature is changed
(c) the shape of the resistor is changed
(d) both material and temperature are changed
In an electrical circuit three incandescent bulbs A, B and C of rating 40 W, 60 W and 100 W respectively are connected in parallel to an electric source. Which of the following is likely to happen regarding their brightness?
(a) Brightness of all the bulbs will be the same
(b) Brightness of bulb A will be the maximum
(c) Brightness of bulb B will be more than that of A
(d) Brightness of bulb C will be less than that of B