State whether anelectric heater will consume more electrical energy or less energy per second when the length of its heating element is reduced. Give reasons for your answer. 38. How many joules of electrical energy are transferred per second by a 6 V ; 0.5 A lamp ?(a) 30 J/s(b) 12 J/s(c) 0.83 J/s(d) 3 J/slight bulbs could be39. At a given time, a house is supplied with 100 A at 220 V. How many 75 W, 220switched on in the house at the same time (if they are all connected in parallel)(a) 9340. If the potential difference between the ends of a fixed resistor is halved, the electric power will become:(b) 193(c) 293(d) 393(a) double(b) half(c) four timesCd) one-fourthQuestions Based on High Order Thinking Skills (HOTS)41. State whether an electric heater will consume more electrical energy or less electrical energy per secondwhen the length of its heating element is reduced. Give reasons for your answer.42. The table below shows the current in three different electrical appliances when connected to the 240 Vmains supply :Curpent8.5 AАppliamceKettleLampToaster(a) Which appliance has the greatest electrical resistance ? How does the data show this ?(b) The lamp is connected to the mains supply by using a thin, twin-cored cable consisting of live and neutralwires. State two reasons why this cable should not be used for connecting the kettle to the mains supply.(c) Calculate the power rating of the kettle when it is operated from the 240 V mains supply.(d) A man takes the kettle åbroad where the mains supply is 120 V. What is the current in the kettle when it43. A boy noted the readings on his home's electricity meter on Sunday at 8 AM and again on Monday at 8 AM(see Figures below).429 35(a) What was the meter reading on Sunday ?(b) What was the meter reading on Monday ?(c) How many units of electricity have been used ?(d) In how much time these units have been used(e) If the rate is Rs. 5 per unit, what is the cost of electricity used during this time ?44. An electric bulb is rated as 10 W, 220 V. How many of these bulbs can be connected in parallel across thetwo wires of 220 V supply line if the maximum current which can be drawn is 5 A ?45. Two exactly similar electric lamps are arranged (i) in parallel, and (ii) in series. If the parallel and seriescombination of lamps are connected to 220 V supply line one by one, what will be the ratio of electric powerconsumed by them?ELECTRICITY61ANSWERS2. 60 watt bulb4. 484 29. Four times10. The electric lamp consumes energy at the rate of 36 J/s17. 6.6 kWh ; 10 A11. 4 A14. 18.0 x 1015. 110 W16. 2 A ; 100 Q18. 59.4 kWh19. () 100 W (i) 625 222. TV set uses 0.25 kWh energy whereas toaster uses 0.20 kWh energy. So, TV uses more energy.20. (a) 18.18 A (b) 12.1 2 (c) 8 kWh (4) ? 36.80 21. 1.1 kW ; 2.2 kWh220 V23. () 8 W(ti) 8 W24. (a)(b) 0.45 A (C) 356.4 kJ25. (a) 2300 W or 23 kl40 Wso w(b) 1,38,000 J or 138 kJ(d) ? 39.00 30. (b)41. More electrical energy ; Power is inversely proportional to resistanceflowing in it (b) Large current drawn by kettle ; Earth connection needed () 2040 W (d) 4.25 A43. (a) 42919 (b) 42935 () 16 units (d) 24 hours (e) Rs. 80 44. 110 bulbs28. 92 J/s31. (d) 32. (c) 33. (b) 34. (a) 35. (c) 36. (d) 37. (d) 38. (đ) 39. (c) 40. (d)26. Rs. 55.0027. 2.99 kWLamp ; Least currentEffects Produced by Electric CurrentAn electric current can produce three important effects. These are: (1) Heating effect, (2) Magneticeffect, and (3) Chemical effect. We will now discuss the heating effect of current. The magnetic effect ofemical effect of current will be described incurrent will be discussed in the next Chapter whereas thehigher classes.HEATING EFFECT OF CURRENTWhen an electric current is passed through a high resistancewire, like nichrome wire, the resistance wire becomes very hotand produces heat. This is called the heating effect of current.The heating effect of current is obtained by the transformation ofelectrical energy into heat energy. Just as mechanical energy usedto overcome friction is converted into heat, in the same way,electrical energy is converted into heat energy when an electric

Energy per second gives power of an object. That is, Power (P) = Energy/time

Answered: State whether anelectric heater will…

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter1: Units, Trigonometry. And Vectors

Section: Chapter Questions

Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...