(Board Term I, 2013) Potential difference across A and B = V (1/3, Board Term I, 2015) Since heat produced by the electric current is equal to work done, W A current of 1.6 mA flows through a conductor. (i) It is a straight line passing through origin. Electric power (P): The electric work done per unit time is called electric power. Internal resistance: The resistance offered by the electrolyte inside the cell, to the flow of current, is known as the internal resistance of the cell. (2018) It offers low opposition in the flow of current. (2020) (Board Term I, 2017) Electric power is also defined as the electric energy consumed per unit time. (a) Refer to answer 37. From Ohms law, V = IR Electric Current: The amount of flow charge through any cross-sectional area of a conductor in unity time is called Electric Current. A cell or a battery can be used to maintain a potential difference between the ends of a conductor. Substituting \(\frac { Q }{ t }\) = I in equation (i), we get, Two bulbs of 100 W and 40 W are connected in series. Rara Academic | Developed By Rara Theme. (ii) directly proportional to resistance for a given current, and (c) Total effective resistance of the circuit. Find the ratio of equivalent resistance in two cases. The heating effects of electric current and its applications are also discussed in detail. Activity 13.4. (a) Given, voltage of the battery = 2V + 2V + 2V = 6 V (ii) To obtain a equivalent resistance of 6 , we have to connect two 9 resistors in series and then connect the third 9 resistor in parallel to the series combination as shown in the figure (b). An electric bulb is rated 100 W, 250 V. In time t if n electrons pass through the metallic conductor, then the total charge that has flown is given by, Q (charge) = n e (charge on an electron). The expression for the electrical energy spent in flow of current through an electrical appliance in terms of current, resistance and time is. (b) Power of each bulb P1 = 100 watt V-I graph for an ohmic conductor can be drawn as given in figure. Find: (b) the p.d. = 400 W 8 h = 3200 Wh = 3.2 kWh (i) Current through circuit, I = \(\frac{V}{R}=\frac{10}{30} \mathrm{~A}=\frac{1}{3} \mathrm{~A}\) t = 1 s Milliampere is written as mA and microampere as pA. Here, V= 220 V,/= 2.5 A All of those advantages come with a price tag, however. Reason (R) : Bronze is an alloy of copper and tin and it is not a good conductor of electricity. As \(\frac{1}{R_{e q}}=\frac{1}{R_{1}}+\frac{1}{R_{2}}+\frac{1}{R_{3}}\) Thus, I = Q/t The unit of current is ampere (A). Your Mobile number and Email id will not be published. (i) What do you infer from this graph? Hence, the value of current for V = 10 volts is 5 amperes (or 5 A). The current flows through the circuit when the electric cell is in a closed circuit. Resistivity, = \(\frac { RA }{ l }\) It does not store any personal data. Thus, R2 > R1 > R3. Given figure shows the series combination of three resistors R1, R2 and R3 connected across a voltage source of potential difference V. or Req = 3 , Question 38. P = \(\frac { V^2}{ R }\), Question 53. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. Applying Ohms law separately to the two resistors, we have. ELECTRIC CURRENT IN CONDUCTORS Conductors are those materials which can conduct electricity. Magnetic field produced due to circular loop. (ii) Negative charge. Define one ampere. Draw a labelled circuit diagram to verify this law in the laboratory. is equal to the terminal voltage. (d) start from the middle and end at or n = \(\frac { 1200 }{ 1.610^{-19} }\) = 7.5 1021. Calculate the resistivity of the material of a wire of length 1 m, radius 0.01 cm and resistance 20 ohms. R = \(\frac { l }{ A }\) V-I graph for a conductor is as shown in the figure (c) (A) is true, but (R) is false. (Board Term I, 2017) The cookie is used to store the user consent for the cookies in the category "Other. This means; 1 = \(\frac { 1V }{ 1A }\) Such materials are called bad conductors. Since joule is the unit of work and Coulomb is the unit of charge, 1 volt of electric potential difference is equal to the 1 joule of work to be done to move a charge of 1 coulomb from one point to another in an electric circuit. \(\frac{1}{R_{\mathrm{eq}}}=\frac{1}{R_{1}}+\frac{1}{R_{2}}+\frac{1}{R_{3}}=\frac{1}{3}+\frac{1}{4}+\frac{1}{6}=\frac{9}{12}\) In parallel combination, the potential difference across each resistor is the same and is equal to the total potential difference. Resistance of a wire varies inversely as the area of cross section of the wire i.e., Resistance of a wire is directly proportional to its length, i.e., R l and varies inversely as the area of cross section of the wire i.e., R 1 / a or R 1 / r2. An electric kettle is rated 2.5 kW, 250 V. I = I1 + I2 + I3 = 0.2 + 0.6 + 1.2 = 2 A Two wires A and B are of equal length and have equal resistances. (b)Express the power P in terms of current and resistance explaining the meanings of symbols used there in. (i) Kilowatt hour (kWh) is the household unit of electricity. A battery of emf 15 V and internal resistance 3 ohm is connected to two resistors of resistances 3 ohm and 6 ohm in series. 15 V and internal resistance 2 ohmis connected to two resistors of resistances 4 ohm and 6 ohm joined in series. (b) Both (A) and (R) are true, but (R) is not the correct explanation of the assertion (A). Your Mobile number and Email id will not be published. Name the material used for making a fuse wire. Batteries produce direct current. It is melted and drawn into a wire of half its original length. (a) The maximum resistance can be obtained from a group of resistors by connecting them in series. The power rating is an electrical appliance such as electric bulb, geyser etc. (Board Term I, 2016) (a) The total resistance of circuit = R + r, (c) p.d. Answer: 1 kWh = 1000 W 1 h (b) The necessary condition for a conductor to obey Ohms law is that the temperature should remain constant. (a) To calculate the resistance of the appliance, the expression is: (b) The safe limit of current in it, while in use is. The rate of electron flow in anelectrical conductoris measured in Ampere. 20.= \(\frac{l}{\pi r^{2}}\) = \(\frac{1 \mathrm{~m}}{3.14 \times\left(10^{-4}\right)^{2} \mathrm{~m}^{2}}\) But given, R = R \(\frac { l }{ A }\) = \(\frac { 2l }{ A }\) or A = 2A, Question 15. The heating of resistor because of dissipation of electrical energy is commonly known as Heating Effect of Electric Current. If the radius of a current carrying conductor is halved, how does current through it change? (a) Power consumed is minimum when current through the circuit is minimum, so the two resistors are connected in series. There are two types of charge = P t = 750 W 2h = 1.5 kWh Answer: An electric press is rated 750 W, 230 V. Series resistance of two 1 ohm resistors, Therefore we can say that 2 ohm resistors are connected in parallel across X and Y. (c) Kilowatt is unit of power and kilowatt hour is a unit of energy. V = 225V. Magnetic effect of electric current class 10 cbse. Fuse of 1A, 2A, 3A, 5A, 10A, etc., used for domestic purpose. or P = \(\frac { W }{ t }\) These precise answers help students during exam preparation as the answers are well structured, according to their individual understanding capacities. (b) Current I = 1.25 A [calculated in part (a)]. A fuse wire melts at 5 A. According to the U.S. Energy Information Administration, most of the nations electricity was generated by natural gas, nuclear energy, and coal in 2020. The heating of electric bulb happens because of heating effect of electric current. Thus. Electricity Class 10 MCQs Questions with Answers. Total energy consumed in one day R = \(\frac { l }{ A }\) Two wires of the same material and same length have radii 1 mmand 2 mmrespectively. (c) one-fourth As graph is a straight line, so it is clear from the graph that V I. 8 W. Question 62. Electric Fuse: Electric fuse is used to protect the electric appliances from high voltage if any. (b) Total current in the circuit, 1= I10 + I20 + I30 Thus resistance of filament increases with the increase in temperature. A Since, the potential difference across R1, R2, and R3 is the same = V If the current drawn by the bulb is 0.50 A, find its power. S.I. Question 59. 1 kWh = 3.6 x 106 watt second = 3.6 106 J. Rs = R1 + R2 = 15 + 15 = 30 (b) Current I = 0.25 A [calculated in (a) part], Now, excluding internal resistance total resistance = 4.5 + 0.7. The maximum resistance which can be made using four resistors each of 2 is Give a reason of your answer. (b) What safe current can be passed through it? Use this circuit to find the value of the following : The positive particles of conductor create hindrance to flow of electrons, because of attraction between them, this hindrance is the cause of resistance in the flow of electricity. This means R will decrease with an increase in the area of conductor and vice versa. (a) Copper or aluminium are the materials used for making connection wires because they have small specific resistance and hence the wires of these materials possess negligible resistance. Give reason for your answer. e.m.f : When the cell is in open circuit, the potential difference between the terminals of the cell is called its electro-motive force or e.m.f. Change the positions of ammeter and note the reading of ammeter each time. R = \(\frac{V^{2}}{P}=\frac{(220)^{2}}{40}\) = 1210 = 2 volt and internal resistance r = 1 ohm connected to an external resistance R = 4 ohm. (b) Electric laundry iron and electric heater are based on heating effect of electric current. (iv) Resistance depends on the nature of conductor since different substances have different concentration of free electrons. AP Economics (Macro) Do colleges look at AP Physics 1? I = I1 + I2 + I3 . Silver has resistivity equal to 1.60 10-8 m and copper has resistivity equal to 1.62 10-8 m. Derivation of formula for electric power: Name three factors on which the resistance of a wire depends and state how it is affected by the factors stated by you? Electric Current, by definition, means the rate of flow of electrons in a conductor or rate of flow of charge. (c) 10 (a) Resistance is directly proportional to length of the wire and inversely proportional to the square of radius of the wire. R = \(\frac { V }{ I }\) S.I unit is Watt(W). R \(\frac { 1 }{ A }\). Two resistors A and B of 4 ohm and 6 ohm, respectively are connected in parallel. (a) Draw a labeled diagram of the arrangement. (a) 2 1 / R = 1 / R1 + 1 / R2 + 1 / R3 + 1 / R4. A cell ofe.m.f. (b) Compute the heat generated while transferring 96000 coulomb of charge in two hours through a potential difference of 40 V. (2020) Example 1: Find the amount of electric charge flowing through the circuit if an electric current of 5 A is drawn by an electric appliance for 5 minute. Edison developed direct current current that runs continually in a single direction, like in a battery or a fuel cell. EMF: The potential difference between the two terminals of a cell, when there is no current flowing through the circuit. (c) What is the cause of resistance offered by the metallic wire in the flow of current through it? To know more about Conductors and Insulators, visit here. Materials having a resistivity in the range of 10-8 m to 10-6 m are considered as very good conductors. The cookies is used to store the user consent for the cookies in the category "Necessary". Question 11. Heating Effect of Electric Current: When electric current is supplied to a purely resistive conductor, the energy of electric current is dissipated entirely in the form of heat and as a result, resistor gets heated. Question 33. = 40 96000 = 3.84 106 J = 3.84 MJ. (c) 2.5 CBSE Notes Class 10. Let us discuss the example problems related to electric current. A uniform wire with a resistance of 27 ohm is divided into three equal pieces and then they are joined in parallel. During the early years of electricity, direct current (shorthanded as DC) was the standard in the U.S. From equations (i) and (ii) P = \(\frac { E }{ t }\) 1 W = 1 volt 1 ampere = 1 V A, (b) Given, V = 5 V and I = 500 mA = 0.5 A (Board Term I, 2013) How much does the resistance change if the diameter is doubled without changing its length? Therefore in a long conductor, the number of collisions of free electrons with the positive ions will be more when compared to a shorter conductor. The potential difference between two points is defined as the difference in electric potentials at the two given points. M.A.K study adda. (ii) The voltage of the electricity that is generally supplied to a house is 220 volt. Give a reason. 1A (microampere) = 106 A. Ammeter: An apparatus to measure R = \(\frac { 10 V }{ 5A }\) = 2 Thus, generation of heat by electric current while passing through a conductor is an inevitable consequence. An electric bulb of resistance 500 ohm draws current 0.4 A from the source. We know, from Ohms Law that, Which will have more resistance? We, know that, So, greater the resistivity, the more the resistance is and the smaller the resistivity, the lesser the resistance. (Electric Current) Objective. or Req = \(\frac { 12 }{ 9 }\) = \(\frac { 4 }{ 3 }\) = 1.33 , (ii) Since, potential difference across each resistor connected in parallel is same. Represent it graphically. (i) Amount of charge Q passed through any area of cross-section is given by I = \(\frac { Q }{ t }\) Answer: A cell of e.m.f. By going through Selina Solutions students come to understand the topics clearly, which they might have missed during class hours. The diagram below in Fig., shows the arrangement of five different resistances connected to a battery of e.m.f. A cell of e.m.f. He received his Ph.D. in physics from the University of California, Berkeley, where he conducted research on particle physics and cosmology. The Power of 1 watt is a rate of working of 1 joule per second. (d) : The inverse of the slope of I-V graph gives the resistance of the material. Electric Current = charge flowing through any conductor per unit time.Or. With the increase in temperature, specific resistance of a semi-conductor decreases. Example 1: Calculate the current through the circuit in which the voltage and resistance be 15V and 3 respectively? Write their power, voltage rating and approximate time for which each one is used in a day. 4 V and internal resistance 2.5 ohm. The difference of electric potential between any two points in the electric field is called Electric Potential difference. (b) Under what condition is the emf of the cell equal to its terminal voltage? Rs = \(\frac{1}{5}+\frac{1}{5}+\frac{1}{5}+\frac{1}{5}+\frac{1}{5}\) 1 , Question 27. The class 10 science chapter 12 Electricity attempts to answer question like what constitutes electricity, what are some of the factors that control or regulate the flow of electricity and how does electricty flow in an electric circuit. (iii) Equivalent resistance of the circuit, Req can be obtained by Ohms law 4. (a) the direction of magnetic field at a point is taken to be the direction in which the north pole of a magnetic compass needle points. unit of resistivity () is m. State ohms law. (iii)The energy supplied in kWh to the three heaters in 5 hours. Which will have more resistance? This cookie is set by GDPR Cookie Consent plugin. Solution:The given parameters are, Choose from the following the statements that holds true for this graph. So, R = \(\frac { R }{ 4 }\) = \(\frac { 16 }{ 4 }\) = 4 Examples: All metallic conductors such as silver, aluminium, copper, iron etc. R = \(\frac { l }{ A }\), where is resistivity of the material of the wire. (b) If you have four 8 resistors and the effective resistance is also 8 then the two 8 resistors are connected in series. R I, (2) Area ol cross section of the conductor: (Ireater the cross-sectional area of the conductor, less will be the resistance. V1, V2 and V3 are the potential differences across resistors R1, R2 and R3 respectively. For a collision occurring between object 1 and object 2 in an isolated system, the total momentum of the two objects before the collision is . At any point on the graph, resistance is the ratio of values of V and I. Ohms Law: According to this law Under the constant physical condition the potential difference across the conductor is directly proportional to the current flowing through the conductor. Answer: Notes for Class 10. Electric Current is a scalar quantity. Answer: Introduction to Chapter 13 Magnetic Effects of Electric Current. (b) \(\frac { 3A }{ 2 }\) Answer: Two lamps, one rated 100 W; 220 V, and the other 60 W; 220 V, are connected in parallel to electric mains supply. Calculate: (a) the power of bulb and (b) the potential difference at its end. = 1000 watt hour = 1 kWh = 1.9 10-7 m unit of Electric Potential is JC-1 or volt (V). What are non-ohmic resistors? This is not so in case the devices are connected in series because when one device fails, the circuit is broken and all devices stop working. Question 13. i.e., H = I Rt The heating effect of current is applied in the working of electrical heating appliances such as electric kettle, electric iron, room heaters, water heaters (geysers), etc. A battery of e.m.f. I30 = \(\frac{V}{R}=\frac{6}{30}\) = 0.2 A (a) What would be the reading of the ammeter? I = \(\frac { P }{ V }\) What is meant by 1 ohm resistance? How much current will the bulb draw if connected to a 250 V supply? Your Mobile number and Email id will not be published. Now, A = r, so new radius is twice the previous one. (e = 1.6 10-19 C). of the cell. When it is connected to a conductor, it produces electric current and, maintain the potential difference across the ends of the conductor. = 6.28 10-7 m, Question 21. V= V1 + V2 + V3 . We define the electric potential difference between two points in an. = (5 + 10 + 15) = 30 A cell supplies a current of 1.2 A through two 2 ohm resistors connected in parallel. Hence, by replacing 40 W bulb to 25 W bulb, having same source of voltage the amount of current flows decreases while resistance increases. For the given circuit Combination of resistors (Series and Parallel combination), the heating effect of electric current and electric power. It does not obey the Ohms law i.e., V / I is not same for all values of V or I. Class 10 Physics Notes - Chapter 14 - Current Electricity - Numerical Problems. The amount of heat produced in a wire on passing current through it, depends on the following three factors. (2020) Let, three resistors R1, R2, and R3 get connected in series. (vi) Electric bulb (d) (A) is false, but (R) is true. AP Chemistry. Question 5. If A and B are the resistivities of wire A and B respectively then (c) : A group of resistors can produce maximum resistance when they all are connected in series. A cell is a source of potential difference, which is created inside it due to internal chemical reactions. (ii) Open plug key Question 4. 6.241018 charge carriers, moving in one second. Refer to answer 17(i) The given solutions are as per the 2019-20 Concise Selina textbook. Its S.I. Do NOT follow this link or you will be banned from the site! Answer: (i) The specific resistance for metals is low, since it allows most of current to pass through it. (Board Term I, 2016) The graph of V (potential difference) versus I (electric current) is always a straight line. The current through the 100 W bulb is 1 A. Current drawn l = \(\frac { P}{ V }\) = \(\frac { 40}{ 220 }\) = 0.18 A There are two kinds of current electricity: direct current (DC) and alternating current (AC). Answer: Name the device which is often used to change the resistance without changing the voltage source in an electric circuit. (b) Two wires A and B are made of copper. (c) : Metals and alloys are good conductors of electricity. The expression (iv) is known as Joules Law of Heating, which states that heat produced in a resistor is directly proportional to the square of current given to the resistor, directly proportional to the resistance for a given current and directly proportional to the time for which the current is flowing through the resistor. It has less or no free electrons. (b) We know that R = 2 ohm from the above calculation. So, V1 = V2 = V3 = 6 V We, know that (i) the current required. H = IRt or Req = 3 , Question 42. If it is desired that the fuse wire of same material melt at 10 A, then whether the new fuse wire should be of smaller or larger radius than the earlier one? 3.0 V supplies current through a circuit in which resistance can be changed. All materials fall into one of the two broad categories: Conductors and Insulators. The cookie is used to store the user consent for the cookies in the category "Performance". 3. = \(\frac{5+3+2}{30}=\frac{10}{30}=\frac{1}{3}\) unit of electric power is watt (W). Answer: Question 16. So, at 10 A, the new fuse wire of same material and length has larger radius than the earlier one. How can we determine the resistance of the resistor from this graph? Assuming that all the electrical work done or all the electrical energy consumed is converted into heat energy, we can write Heat produced in place of Work done in the above equation. Define the term resistance. Answer: 2 V and internal resistance 1.2is connected to an ammeter of resistance 0.8and two resistors of 4.5and 9as shown in fig. Direction: The direction of conventional current (or practical current) is opposite to the flow of electrons. The electricity is an electromagmentic wave and the speed of electromagnetic waves always equal to 310^8 m/s that is the speed of light. October 6, 2020 by Prasanna. Question 8. Calculate the rated power and resistance of the bulb when it glows. For which of the following substances, resistance decreases with increase in temperature? Answer: (1/5, Board Term 1,2017) P = (\(\frac { V }{ R }\))2 R = \(\frac { { V }^{ 2 } }{ R }\) Watt The electric laundry iron, electric toaster, electric oven, electric kettle and electric heater are some common devices based on heating effect of current. A parallel combination of two resistors, in series with one resistor. I / V is the reciprocal resistance of the conductor i.e. Conversely, an electric current of A represents 1 C of unit electric charge carriers flowing past a specific point in 1 s. The MKS unit of charge is the Coulomb, while the cgs unit is the electrostatic unit, or esu. Bihar board Class 12th 10th Admit Card 2023 Download link | BSEB inter Admit card download The continuous flow of electrons in an electric circuit is called an electric current. Direct current is not easily converted to higher or lower voltages. E2 = P2 t = 100 watt 10 hours (Board Term I, 2017) Also V = IR [According to Ohms Law] V =\(\frac { W }{ Q }\), S.I. One coulomb is nearly equal to 6 1018 electrons. Let lA, aA and RA be the length, area of cross-section and resistance of wire A and lB, aB and RB are that of wire B. Electric Power = \(\frac { Electric\quad work\quad done }{ Time\quad taken }\) (a) The maximum resistance can be produced from a group of resistors by connecting them in series. When the resistors are connected in series, the current flowing through each resistor is the same and is equal to the total current. (1/5, Board Term 1,2015) Your Mobile number and Email id will not be published. \(\frac { Total voltage }{ Total resistance }\) resistance of lamp Answer: Cause of Resistance in a Conductor: Flow of electrons in a conductor is electric current. (Board Term I, 2016) Explain with reason. (ii) As, P = \(\frac{V^{2}}{R} \Rightarrow R=\frac{V^{2}}{P}=\frac{25}{2.5}\) = 10 (Board Term I, 2017) Potential diffrence (V) = ? i.e., P = VIt (a)Name two factors on which the specific resistance of a wire depends? A given wire is stretched to double its length, Therefore length l = 2l and area of cross section a = a / 2. Which of the following combinations have the same equivalent resistance between X and Y? This is known as healing effect of current, file amount of heat (77) produced in time t is given by Joules law of heating. Define resistance and give its SI unit. and Rs = 2 + 1 = 3 , Question 35. An atom has a positively charged nucleus and negatively charged electrons revolving around it. (b) When no current is drawn, then the e.m.f. (i) power Calculate the resistance of a metal wire of length 2m and area of cross section 1.55 106 m, if the resistivity of the metal be 2.8 10-8 m. Give a reason for your answer. NCERT Solutions For Class 10 Science Chapter 11: The Human Eye and the Colourful World. In the given circuit diagram calculate Ohms law: Refer to answer 7. (ii) SI unit of resistivity is m. Question 18. (AI 2019) How do you use it to calculate (a) the resistance of the appliance and (b) the safe limit of the current in it, while in use? (i) As P = V7 Which of the following is an ohmic resistance? Rate of flow means, the amount of charge flowing through a particular area in unit time. Question 46. (b) Energy consumed by electric refrigerator in a day = Power x time Current Electricity Class 12. From the expression of Ohms Law, it is obvious that electric current through a resistor is inversely proportional to resistance. or Rs = R1 + R2 + R3 Workdone = charge potential or potential difference, Mathematically,W = Q V = Q ( V2 V1) Joule. Stay tuned with BYJUS to learn more about other Physics related concepts. The straight line A is more steeper than the line B because the resistance of conductor is more at high temperature T1 than at low temperature T2. A steady current of 0.5 A flows through the circuit. 50. fuse melts at (5)R joules of heat. Magnetic field. All materials resist current flow upto some degree. or I = \(\frac { 3 }{ 2 }\) A = 1.5 A But there was one problem. Define electric current. RA = A \(\frac{l_{A}}{a_{A}}\) and RB = B \(\frac{l_{B}}{a_{B}}\), As RA = RB Draw a circuit diagram for a circuit consisting of a battery of five cells of 2 volts each, a 5 resistor, a 10 resistor and a 15 resistor, an ammeter and a plug key, all connected in series. Find their equivalent resistance. Its value in S.I. (iii) energy consumed when it is lighted for 2 \(\frac { 1 }{ 2 }\) hours. (a) Expression for electrical power spent in flow of current through a conductor in terms of resistance and potential difference is, (b) Expression for electrical power spent in flow of current through a conductor in terms of current and resistance is, Electrical power P is given by the expression P = (Q V) time. 1 A = 1 C s-1. V = 15V A closed-loop path which a current takes is called an electric circuit. Draw diagram and find the total resistance. As a result the number of collisions increases. (3), Now, putting Q = I t and V = I R in equation (1), we get. Powered by WordPress. It states that the potential difference V, across the ends of a given metallic wire in an electric circuit is directly proportional to the current flowing through it, provided its temperature remains the same. (d) R2 > R1 > R3 Watt is the S.I. In this case, the total resistance of the system is equal to the sum of the resistance of all the resistors in the system. Then, V = IRs (iii) Find their equivalent resistance. A combination consists of three resistors in series. Answer: To know more about Ohms law, visit here. Answer: (a). Here, r = 0.01 cm = 10-4 m, = 50 10-8 m and R = 10 How does the resistance of a wire depend on its length? Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. S.I. Calculate: (i)The total current taken from the supply. Wattage of electric iron = Power unit of electric power is Watt. Question 9. Explain the process by which this device does so. Selina Solutions Concise Physics Class 10 Chapter 8 Current Electricity provides complete information regarding the concept of Current. Answer: Students can download the Selina Solutions Concise Physics Class 10 PDF free from the links available here. Four resistors each of resistance 2 ohm are connected in parallel. What does the positive and negative sign of potential convey? R = 4 (b) What is the potential difference across the terminals of the cell? R = \(\frac { R }{ 4 }\) = \(\frac { 100 }{ 4 }\) = 25, Question 22. Now when the length is doubled, l = 2l and A = \(\frac { A }{ 2 }\) Its S.I. Hence find the electrical energy consumed by each in a month of 30 days. Revision Notes A sustained electric current flows through a conductor only when it is connected to a source of emf. How is the resistance of the resistor determined from this graph? (ii) A bulb is rated 5V; 500 mA. so l = \(\frac{10}{50 \times 10^{-8}} 3.14 \times\left(10^{-4}\right)^{2}\) Now, the above resistances are arranged in parallel, 1 / r = 1 / r1 + 1 / r2 + 1 / r3 + 1 / r4, In the circuit shown below in figure, calculate the value of x if the equivalent resistance between the points A and B is 4 ohm, Calculate the effective resistance between the points A and B in the circuit shown in figure, Let the net resistance between the points X and Y be R, Therefore, we can say that three 1 ohm resistors are connected in series between points A and B, Let the net resistance between points A and B be RAB. What does the direction of current convey? (b) The connection wires are made thick to consider their resistance as negligible to the flow of current through the circuit. For each case draw a circuit diagram and calculate the current through the battery. We know that electric work done, W = V I t or P = \(\frac { VIt }{ t }\) (d) four times (2020) Let I be the length and a be the area of cross section of the resistor with resistance, R = 1 Ohm. Therefore (b) Both (A) and (R) are true, but (R) is not the correct explanation of the assertion (A). 1200 = n 1.6 10-19 Answer: (c) equivalent resistance is less than either of the two resistances. (ii) total current drawn from the battery, and Explain your answer. Thus when one lamp is connected across the mains, it draws 0.25 A current. 1W = 1 volt 1 ampere = 1V 1A unit of length is m. Hence, unit of resistivity () = \(\frac { \Omega \times { { m }^{ 2 } } }{ m }\) = m The +ve charge flows from higher to lower potential. (d) 25 (2020) The wire A is long and thin while the wire B is Short and thick. Necessary cookies are absolutely essential for the website to function properly. Answer: unit is ohm-meter (m). Similarly, I2 = \(\frac { 6A }{ 4 }\) = 1.5 A and I3 = \(\frac { 6 }{ 6 }\) A = 1 A. R = \(\left(\frac{5 \times 10^{-8} \times 50 \times 10^{-2}}{0.01 \times 10^{-6}}\right)\) But its sends current 0.5 A when it is connected to an external resistance of 3.9 ohm. (ii) Length of Conductor: Resistance (R) is directly proportional to the length of the conductor. (i) State one difference between kilowatt and kilowatt hour. R depends upon nature, geometry and physical condition of the conductor. How does specific resistance of a semi-conductor change with the increase in temperature? Draw the symbols of commonly used components in electric circuit diagrams for The SI unit of electric current is Ampere and is denoted by the letter A. Ampere is defined as one coulomb of charge moving past a point in one second. Question 31. The equivalent resistance of two resistors is given as: To know more about Resistors in Series and Parallel, visit here. List the names of three electrical gadgets used in your house. 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