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question_answer1) You have two metallic wires of resistances and How will you connect these wires to get the effective resistance of?
question_answer2) A bulb in an electric circuit is glowing. Is it a closed or open electric circuit?
question_answer3) An ammeter has 20 divisions between zero mark and 2 A mark on its scale. What is the least count of ammeter?
question_answer4) A student finds that there are 20 divisions between zero mark and 1 V mark of a voltmeter. Find the least count of this voltmeter.
question_answer5) The current flowing through a resistor connected in an electric circuit and the potential difference applied across its ends are shown in figure. What is the value of the resistance of the resistor?
question_answer6) Choose all the apparatus for performing the experiment to determine the equivalent resistance of two resistors when connected in series.
question_answer7) A student of class X performed experiment on series and parallel combination of two given resistors R-^ and R^ which obeys Ohm's law. Plot the V-I graph.
question_answer8) A student using the same two resistors, ammeter, voltmeter and battery makes two circuit connecting the two resistors first in series and other in parallel. If the ammeter and voltmeter readings in both the cases be and respectively. Write his observations.
question_answer9) What happens to the resistance as the conductor is made thicker?
question_answer10) What do the following symbols mean in circuit diagram? (a) (b)
question_answer11) The figure shows three resistors. Find the combined resistance.
question_answer12) What happens to the other bulbs in a series circuit if one bulb blows off?
question_answer13) What are the important effects of electric current?
question_answer14) Draw the proper representation of series combination of cells obtaining maximum potential.
question_answer15) How can an ammeter be converted into a voltmeter?
question_answer16) Draw a circuit diagram using a cell of two batteries, two resistors of each connected in series, a plug key and a rheostat.
question_answer17) What charge is carried by a conductor through which 4.5 A current flows in one minute?
question_answer18) Find the minimum resistance that can be made using five resistors, each of .
question_answer19) Why does an ammeter have negligible resistance?
question_answer20) What causes the potential difference between the two terminals of a cell?
question_answer21) Resistance of an incandescent filament of a bulb is comparatively much more than that when it is at room temperature. Why?
question_answer22) Give two examples for application of heating effect of electric current.
question_answer23) Name and define the smallest commercial unit of electricity.
question_answer24) In how much time will a bulb of 100 W consume an energy of 2 kWh?
question_answer25) What do you understand by the term fuse in an electric circuit?
question_answer26) What do the following circuit symbols represent? (a) (b)
question_answer27) Write the symbols used in electric circuits to represent (a) (b)
question_answer28) Write one function of the given symbol.
question_answer29) Why closed path is required for the flow of current?
question_answer30) When two ends of a metallic wire are connected across the terminals of a cell, some potential difference is set up between its ends. In which direction electrons are flowing through the conductors?
question_answer31) List any two important properties of electric charge.
question_answer32) Suggest any two smaller units of current.
question_answer33) What is the resistance of air gap?
question_answer34) The resistance of a resistor is kept constant and the potential difference across its two ends is decreased to half of its former value. State the change that will occur in the current flowing through it.
question_answer35) The voltage-current (V-I) graph of a metallic circuit at two different temperatures and is shown in figure. Which of the two temperatures is higher and why?
question_answer36) What is the total resistance of n resistors, each of resistance R, connected in parallel?
question_answer37) Nichrome is used to make the element of electric heater. Why?
question_answer38) Why do we use copper and aluminium wires for transmission of electric current?
question_answer39) Alloys are used in electrical heating devices rather than pure metals. Why?
question_answer40) Tungsten is used almost exclusively for filaments of electric bulb. Support your view.
question_answer41) A wire of resistivity is pulled to double its length. What will be its new resistance?
question_answer42) Out of the two wires P and Q shown below, which one has greater resistance? Justify it.
question_answer43) How does the resistance of an ohmic conductor depend on the applied voltage?
question_answer44) Draw the V-J graph for ohmic and non-ohmic conductor. Sol. V-l graph for ohmic resistance is given below V-I Draw a circuit diagram to show
question_answer45) Draw a circuit diagram to show experimental set up for verification of Ohm's law.
question_answer46) An electrician puts a fuse of rating 5 A in that part of domestic electrical circuit in which an electric heater of rating 1.5 kW, 220 V is operating. What is likely to happen in this case and why?
question_answer47) Derive an expression for equivalent resistance in the following case The Plan Decide which resistances are in series and parallel. Solve for series and then for parallel. Combine both the results to get the equivalent resistance.
question_answer48) Why does the chord of an electric heater not glow while the heating element does?
question_answer49) 320 J of heat is produced in 10 s in a resistor. Find the amount of current flowing through the resistor.
question_answer50) An electric bulb is rated 220 V and 100 W. Calculate the power consumed when it is operated on 110V.
question_answer51) Following table gives the resistivity of three samples in m Sample A B C Resistivity Which of them is a good conductor and which of them is an insulator? Why?
question_answer52) Two metallic wires X and Y are connected in series. Wire X has length / and radius r, while wire Y has length 21 and radius 2r. Find the ratio of the total resistance of series combination and the resistance of wire X, if both the wires are of same material.
question_answer53) Two students perform the experiments on series and parallel combinations of two given resistors and and the following V-I graphs. Which of the graph is/are correctly labelled in terms of the words series and parallel? Justify your answer .
question_answer54) What will be the reading of V change if it is connected between B and C? Justify your answer.
question_answer55) Which of the following resistor arrangement A or B has the lower combined resistance?
question_answer56) n resistors, each of resistance R are first connected in series and then in parallel. What is the ratio of the total effective resistance of the circuit in series to parallel combination?
question_answer57) A wire has resistivity . What will be its new resistivity if it is stretched to double of its length? Will the resistance remain the same? (1)
question_answer58) A current of 1 A is drawn by a filament of an electric bulb. Find the number of electrons passing through a cross-section of the filament in 16 s.
question_answer59) if the current I through a resistor is increased by 100% (assume that temperature remains unchanged), find the increase in power dissipated.
question_answer60) 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. Write the order of brightness.
question_answer61) In an electrical circuit, two resistors of and . respectively are connected in series to a 6V battery. Find the heat dissipated by the . resistor in 5 s.
question_answer62) What does quantisation of charge mean?
question_answer63) Define resistivity and state its SI unit.
question_answer64) Find the equivalent resistance in the following circuit
question_answer65) Draw the symbol of (a) plug key open (b) plug key closed. What does each situation mean?
question_answer66) What is an ammeter? How is it connected in a circuit? Draw a diagram to illustrate your answer.
question_answer67) A circuit diagram is given below Calculate (a) current through each resistor. (b) the total current in the circuit. (c) the total effective resistance of the circuit.
question_answer68) Study the following circuit and answer the questions that follows (a) State the type of combination of the two resistors in the circuit. (b) How much current is flowing through (i) and (ii) resistor? (c) What is the ammeter reading?
question_answer69) Draw a circuit diagram of an electric circuit containing a cell, a key, an ammeter, a resistor of in series with a combination of two resistors ( each) in parallel and a voltmeter across the parallel combination. Will the potential difference across the resistor be the same as that across the parallel combination of resistors ? Give reasons. The Plan Make a rough sketch of the circuit using the material given with proper connection, then solve it.
question_answer70) A metallic wire of resistance R is cut into ten parts of equal length. Two pieces each are joined in series and then five such combinations are joined in parallel. What will be the effective resistance of the combination?
question_answer71) Read the following information (a) Resistivity of copper is lower than that of aluminium which, in turn, is lower than that of constantan. (b) Six wires labelled as A, B, C, D, E and F have been designed as per the following parameters. Wire Length Diameter Materials Resistances A 2d Aluminium B d/2 Constantan C d/2 Constantan D 3d Copper E 2d Aluminium F 4d Copper Answer the following questions using the above data (a) Which of the wires has maximum resistance and why? (b) Which of the wires has minimum resistance and why? (c) Arrange and in ascending order of their values. Justify your answer.
question_answer72) A battery E is connected to three identical lamps P, Q and R as shown in figure. Initially the switch S is kept open and the lamp P and 0 are observed to glow with some brightness. Then switch S is closed. How will the brightness of glow of bulbs P and Q will change? Justify your answer.
question_answer73) Two resistors, with resistance and respectively are to be connected to a battery of emf 6 V so as to obtain (a)(i)minimum current (ii)maximum current (b) How will you connect the resistances in each case? (c) Calculate the strength of the total current in the circuit in the two cases.
question_answer74) For the circuit shown in the given figure, What is the value of (a) current through resistor? (b) potential difference across resistor?
question_answer75) (a) A current of 1 ampere flows in a series circuit having an electric lamp and a conductor of when connected to a 10 V battery. Calculate the resistance of the electric lamp. (b) Now if a resistance of is connected in parallel with this series combination, what change (if any) in current flowing through conductor and potential difference across the lamp will take place? Give reason.
question_answer76) Five resistors are connected in a circuit as shown. Find the ammeter reading when the circuit is closed.
question_answer77) Find the total resistance between the points A and C in the given circuit shown.
question_answer78) Find the equivalent resistance of the following circuit
question_answer79) An electric iron consumes energy at a rate of 840 W when heating is at the maximum rate and 360 W when the heating is at the minimum. The applied voltage is 220 V. What is the value of current and the resistance in each case?
question_answer80) A heater coil connected to 200 V has a resistance of 80. If the heater is plugged in for the time t such that 1 kg of water at 20°C attains a temperature of 60°C. Find (a) power of heater (b) heat absorbed by water (c) the value of t in seconds.
question_answer81) A hot plate of an electric iron connected to a 200 V line has two resistance coils A and B, each of resistance, which may be used separately in series or in parallel. What are the currents in three cases?
question_answer82) Compare the power used in resistor in each of the following circuits (i) a 6 V battery in series with and resistors, (ii) a 4 V battery in parallel with and resistors.
question_answer83) Two resistors of and are connected in parallel. The combination is connected across a 6V battery of negligible resistance. Calculate (a) the power supplied by the battery and (b) the power dissipated in each resistor.
question_answer84) Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. Find the ratio of heat produced in series and parallel combination.
question_answer85) An electric geyser rated 1500 W, 250 V is connected to a 250 V line mains. Solve (a) the electric current drawn by it. (b) energy consumed by it in 50 hours. (c) cost of energy consumed if each unit costs Rs. 6.00.
question_answer86) An electric heater is rated at 2 kW. Calculate the cost of using it for 2 hours daily for the month of September, if each unit costs ` 4.00.
question_answer87) In the evening Seema parked her car inside her garage and left for vacation of 15 days. On returning, she tried to start the car but the car did not start. She checked the fuel and engine oil but that were also full. So, she called a mechanic. After examining the car and mechanic connected the charged battery with that of car battery. Then the car started at once. On the basis of above passage, answer the following questions (a) In which combination, the batteries are connected? (b) Draw a circuit diagram for the above said combination. (c) Identify the moral values we get from the passage.
question_answer88) Vishwajeet was doing an experiment by using an ammeter. Suddenly, it fell from his hand and broke. He was fearing that he might be scolded by his teacher. His classmates advised him not to tell the teacher but he refused and told his teacher. On listening to him patiently, the teacher did not scold him as it was just an incident and used the opportunity to show the whole class the internal structure of ammeter. On the basis of above passage, answer the following questions (a) What are the values displayed by Vishwajeet? (b) What is the use of ammeter? How is it connected in the circuit? (c) State the aim of any one experiment where Vishwajeet could have used the ammeter.
question_answer89) Salim lives in a small town and facing some electrical problem in his house. His fuse wire was melted. He changed the fuse wire of his house but it lasted only for few hours and circuit broke. Now he turned off all his electrical devices, reinstalled the fuse wire and one by one switched on the 4 electrical devices to find the defective device. He got one end repaired after removing it from the circuit. On the basis of above passage, answer the following questions (a) What is the use of fuse wire? (b) What type of electrical circuit is seen in the above case? (c) Write the values displayed by Salim.
question_answer90) Shamit and Vishesh were doing an experiment to find equivalent resistance of a combination of resistors connected in series. Shamit made the circuit as follows and could not get the correct results. Vishesh made changes in the circuit and now the findings were matching with the expected result. On the basis of above passage, answer the following questions (a) What changes were made by Vishesh? (b) What would be the findings in the first circuit made by Shamit indicate? (c) What qualities of Vishesh are reflected from this?
question_answer91) Sonam wanted to use copper wire in place of a heater coil as it also had a high melting point. Monika reminded her an another property of the wire and told her what could be ideally used for the same Sonam agreed and the circuit was successfully completed, On the basis of above passage, answer the following questions (a) Which property was reminded by Monika about copper? (b) Which material would have been suggested by Monika? (c) Which qualities of Monika would you appreciate? completed successfully, so it may be nichrome as suggested by Monika because nichrome has high resistivity, so more heat will be generated in it. (1) (c) Qualities of Monika to be appreciated are (i) Scientific temperament (ii) Convincing power (iii) Awareness (1)
question_answer92) Manish had a habit of switching off the appliances if they were used for long. His friends would however, make fun of this habit of him. Without bothering about their remarks, Manish still stuck to his habits. On the basis of above passage answer the following questions (a) Why did Manish switch off the appliances at regular intervals? (b) Do you agree/justify Manish's act? Give reason. (c) Compare and contrast the values of Manish and his friends.
question_answer93) An electrician connected a fuse wire of 15 A rating againwer outlets. Rahul was observing his activity and asked him why he had connected a wrong fuse. The electrician said that it would not be affected by power fluctuations frequently. Rahul, however, scolded him for such wrong practice and got the fuse changed. On the basis of above passage, answer the following questions (a) What values of Rahul are worthy of appreciation? (b) Which characteristics of the electrician would you address? (c) What would had happen if Rahul agreed with the electrician?
question_answer94) (a) State the relation between potential difference, work done and charge moved. (b) Calculate the work done in moving a charge of 4 C from a point at 220 V to and point at 230 V.
question_answer95) (a) The potential difference between two points in an electric circuit is 1 V. What does it mean? Name a device that helps to measure the potential difference across a conductor. (b) Why does the connecting chord of an electric heater not glow while the heating element does? (c) Electrical resistivities of some substances at 20°C are given below Silver Copper Tungsten Iron Mercury Nichrome Answer the following questions using above data (i) Among silver and copper, which one is a better conductor? Why? (ii) Which material would you advise to be used in electrical heating devices and why?
question_answer96) (a) Name an instrument that measures electric current in a circuit. Define the unit of electric current. (b) What do the following symbols represent in a circuit diagram? (i) (ii) (c) An electric circuit consisting of a 0.5 m long nichrome wire XY, an ammeter, a voltmeter, four cells of 1.5 V each and a plug key was set up. (i)Draw the electric circuit diagram to study the relation between the potential difference maintained between the points X and Y and the electric current flowing through XY. (ii) Following graph was plotted between V and I values using above circuit What would be the values of ratios when the potential difference is 0.8 y 1.2 V and 1.6 y respectively? What conclusion do you draw from these values?
question_answer97) and are three identical bulbs connected as shown in figure. Ammeters and are connected as shown. When all the bulbs glow, the current of 3 A is recorded by ammeter A. (a)What happens to the glow of the other two bulbs when bulb gets fused? (b) What happens to the reading of and A when the bulb gets fused? (c) How much power is dissipated in the circuit when all the three bulbs glow together?
question_answer98) Two resistances when connected m parallel give resultant value of , when connected in series the value becomes . Calculate the value of each resistance.
question_answer99) (a) Find the value of current (I) in the circuit given below (b) You have four resistors of each. Show how would you connect these resistors to have effective resistance of ?
question_answer100) State and verify Ohm's law.
question_answer101) Explain briefly how the factors on which resistance of a conductor depends.
question_answer102) How can you show that we prefer parallel circuit?
question_answer103) Three incandescent bulbs of 100 W each are connected in series in an electric circuit. In another set of three bulbs of the same wattage are connected in parallel to the source. (a) Will the bulb in the two circuits glow with the same brightness? Justify your answer. (b) Now, let one bulb in both the circuits get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.
question_answer104) A household uses the following electric appliances refrigerator of rating 400 W for 10 hours each day. (b) two electric fans of rating 80 W each for 6 hours daily. (c) six electric tubes of rating 18 W each for 6 hours daily. Calculate the electricity bill for the household for month of June if cost of electrical energy is Rs. 3.00 per unit.
question_answer105) Define the unit of electric current. [NCERT]
question_answer106) Name a device that helps to maintain a potential difference across a conductor.
question_answer107) [NCERT] Let the resistance of an electrical component remain constant while the potential difference across the two ends of this component decrease to half of its former value. What change will occur in the current flowing through it? [NCERT]
question_answer108) The voltage-current (V-I) graph of a metallic conductor at two different temperature T1 and T2 is shown in figure. At which temperature is the resistance higher?
question_answer109) What determines the rate at which energy is delivered by a current? [NCERT]
question_answer110) How is a voltmeter connected in the circuit to measure the potential difference between two points? [NCER]
question_answer111) Why is resistance less when resistors are joined in parallel?
question_answer112) Why is resistance more in series combination?
question_answer113) What are the special features of a heating wire?
question_answer114) What is the resistance of an ideal ammeter?
question_answer115) What is the resistance of an ideal voltmeter?
question_answer116) Which one has more resistance 100 watt bulb or 60 watt bulb both operating at 220 V?
question_answer117) Write the expression for the heat energy produced in a wire of resistance R and carrying current I.
question_answer118) Name the physical quantity whose unit is J/C.
question_answer119) What is the resistance of an air gap?
question_answer120) What is the commercial unit of electric energy?
question_answer121) What happens to the resistance of a wire if it is made thinner?
question_answer122) In series combination which remains constant?current or voltage?
question_answer123) Which substance is used for making resistance coil of electric heater and why?
question_answer124) Which physical quantity remains constant when resistances are connected in parallel?
question_answer125) How is the ammeter connected in the circuit?
question_answer126) Why is an ammeter connected in series in an electric circuit?
question_answer127) Name two devices in which electricity is converted into heat.
question_answer128) Name the alloy which is used for making the filament of bulbs.
question_answer129) Name the instrument used for measuring potential difference.
question_answer130) Name the instrument used for measuring electric current flowing in electric circuit.
question_answer131) The following table gives the value of electrical resistivity of some materials Material Cooper Silver Constantan Electrical resistivity (in m) Which one of these materials is the best conductor of electricity? [CBSE Delhi 2008]
question_answer132) Why does resistance of a metallic conductor increase with increase in temperature
question_answer133) Why is it not advisable to handle high voltage electrical circuit with wet hands:
question_answer134) Though the same current flows through line wires or the filament of a bulb yet only the latter glows. Why?
question_answer135) Why does an electric bulb become dim when an electric heater in parallel circuit is switched on? Why does dimness decrease after sometime?
question_answer136) Heat is generated continuously in an electric heater but the temperature of its element becomes constant after some time. Why?
question_answer137) A metallic wire of resistance R is cut into ten parts of equal length. Two pieces each are joined in series and then five such combinations are joined in parallel. What will be the effective resistance of the combination?
question_answer138) A wire of length L and resistance R is stretched so that its length is doubled and the area of cross-section is halved. How will its: (a) resistance change? (b) resistivity change? Justify your answer in each case.
question_answer139) In the given circuit diagram, two resistance wires A and B are of same area of cross section and same material, but A is longer than B. Which ammeter Ai or A^ will indicate higher reading for current? Give reason.
question_answer140) (a) The components of an electric circuit are 0.5 m long nichrome wire XY, an ammeter, a voltmeter, four cells of 1.5 V each, rheostat and a plug key. Draw a circuit diagram to study the relation between potential difference across the terminals X and Y of the wire and current flowing through it. (b) State the law that relates potential difference across a conductor with the current flowing through it.
question_answer141) Two wires of equal length, one of copper and the other of manganin (an alloy) have the same thickness. Which one can be used for (i) electrical transmission lines (ii) electrical heating devices? Why?
question_answer142) [CBSE 2008C] A student has drawn the electric circuit to study Ohm's law as shown in figure. His teacher told that the circuit diagram needs correction. Study the circuit diagram and redraw it after making all corrections. [NCERT Exemplar]
question_answer143) Draw a circuit diagram of an electric circuit containing a cell, a key, an ammeter, a resistor of 2 in series with a combination of two resistors (4 each) in parallel and a voltmeter across the parallel combination. Will the potential difference across the 2 resistor be the same as that across the parallel combination of 4. Resistors? Give reason. [NCERT Exemplar]
question_answer144) What is electrical resistivity? In a series electrical circuit comprising of a resistor having a metallic wire, the ammeter reads 5 A. The reading of the ammeter decreases to half when the length of the wire is doubled. Why? [NCERT Exemplar]
question_answer145) On what factors does the resistance of a conductor depend? [NCERT]
question_answer146) Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why? [NCERT]
question_answer147) Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal? [NCERT]
question_answer148) (i) Which among iron and mercury is a better conductor? (ii) Which material is the best conductor and why? [NCERT]
question_answer149) What are the advantages of connecting electrical devices in parallel with the battery instead of connecting them in series? [NCERT]
question_answer150) Three incandescent bulbs of 100 W - 220 V each are connected in series in an electrical circuit. In another circuit another set of three bulbs of the same voltage are connected in parallel to the same source. (a) Will the bulb in the two circuits glow with the same brightness? Justify your answer. (b) Now let one bulb in both the circuits get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.
question_answer151) What would be the reading of ammeter and voltmeter in the given circuit?
question_answer152) Read the following information: (a) Resistivity of copper is lower than that of aluminium which, in turn, is lower than that of constantan. (b) Six wires labelled as A, B, C, D, E, F have been designed as per the following parameters: Wire Length Diameter Material Resistance A Aluminium R1 B Constantan R2 C Constantan r3 D Copper R4 E Aluminium r5 F Copper R6 Answer the following questions using the above data: (a)Which of the wires has maximum resistance and why? (b)Which of the wires has minimum resistance and why? (c)Arrange R1, R2 and R5 in ascending order of their values. Justify your answer.
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