Resistance of a conductor also depends upon nature of material of conductor,temperature of conductor. Variable definition: Something that is variable changes quite often, and there usually seems to be no fixed... | Meaning, pronunciation, translations and examples S.I. Resistance is the hindrance to the flow of charge. copper wire (B)=length (l),area of cross section is more than X. Reading of ammeter in second case is more that of reading in 1st case. Your email address will not be published. 2) Resistance of a conductor is inversely proportional to area of cross section. Resistivity, commonly symbolized by the Greek letter rho, ρ, is quantitatively equal to the resistance R of a specimen such as a wire, multiplied by its cross-sectional area A, and divided by its length l; ρ = RA/l.The unit of resistance is the ohm.In the metre-kilogram-second (mks) system, the ratio of area in square metres to length in metres simplifies to just metres. Resistance in a conductor depends on nature, length and area of cross section of the conductor. Area of cross section: Resistance R is inversely proportional to the area of cross section ( A) of the conductor. Theory. See more. Rather, it is a zigzag path that results from countless collisions with fixed atoms within the conducting material. Calculate the ratio of power consumed in the combination of resistors in the two cases. This is the currently selected item. Variable definition, apt or liable to vary or change; changeable: variable weather;variable moods. Resistance of a wire can be increased or decreased depending on its combinations and connections in a circuit. Solving a circuit with series and parallel resistors . The unpadded, hard plastic handles are uncomfortable to … Economics Chapter 4 Globalisation and The Indian Economy – Notes & Study Material, Economics Chapter 3 Money and Credit – Notes & Study Material, Compounds of Xenon and uses of Noble Gases, Characteristics and Physical Properties of Group 18 Elements, Oxoacids of Halogens and Interhalogen Compounds, English Alphabets with Phonics Pronunciation. It is made of copper wires which is coiled around a ceramic rod and the outer part of the resistor is coated with an insulating paint. A galvanometer with a coil of resistance \$12.0 \Omega\$ shows a full scale deflection for a current of 2.5 mA. Resistor is defined as The main purpose of resistor is to reduce the current flow and to lower the voltage in any particular portion of the circuit. This is the cause that long electric wires create more resistance to the electric current. (b) Establish the relationship between 1 kWh and SI unit of energy. Variable Resistance: The component of an electric circuit which is used to regulate the current; without changing the voltage from the source; is called variable resistance. What is an Electric CircuitIt is a continuous and closed path through which electric current flowsIt contains different components likeCell or BatteryPlug KeyWiresElectric Components (like Ammeter,Voltmeter)Bulb etcWhat is Circuit DiagramIt is a diagram which shows how different components of circui An electron traveling through the wires and loads of the external circuit encounters resistance. Melting point is high or does not burn at higher temperature. How will you convert the galvanometer into (a) an ammeter of range 0 to 7.5 A, (b) a voltmeter of range 0 to 10.0 V? Component that is used to resist the flow of electric current in a circuit is called resistor. Rheostat: This is a device which is used in a circuit to provide variable resistance. Example 1: What will be the resistivity of a metal wire of 2 m length and 0.6 mm in diameter, if the resistance of the wire is 50 Ω. Find the resistance of the same wire of 2 meter length and 0.3 mm thickness. Thus, `text(resistance) ∝ (1)/(text(Area))` of cross section of conductor (A). Aim Experiment To determine the equivalent resistance of two resistors when connected in series. Work your outer thighs as you perform this lateral slide movement. Various parameters like size, type of track and also resistance is used to define a variable resistance. Lateral Slides. Thus, ratio of resistance before stretching to resistance after stretching can be given as follows: Thus, resistance increases four times after stretching of wire. Resistivity does not depend on l and A but on nature of material of which substance is made of. Class 10 Science Electricity Short Answer Type Questions[l] [2 Marks] – Year 2011. The Lifeline Variable Resistance Training Kit is reviewed favorably on Amazon, but it disappointed us. Science Practical Class 10 Resistance In Series Experiment – 2. flow of electrons through them. Length of conductor: Resistance R is directly proportional to the length of the conductor. Business Enquiry (North) 8356912811. Business Enquiry (South) 8104911739. Also known as a Potmeter or Pot, it consists of a resistive element called the track and a sliding contact called the wiper internally where end terminals are attached to the resistive element. These are used to provide a variable resistance by just changing the knob on the potentiometer. Electric Circuit and 10. Nature of material: Some materials create least hindrance and hence are called good conductors. … Author of this website, Mrs Shilpi Nagpal is MSc (Hons, Chemistry) and BSc (Hons, Chemistry) from Delhi University, B.Ed (I. P. University) and has many years of experience in teaching. The particles of conductor create hindrance to flow of electrons; because of attraction between them. Solution: Given, Resistance ( R ) = 50 Ω, Length ( l ) = 2 m, Hence, radius `= 0.3  mm = 3 xx 10^-4  m`, Now, area of cross section of wire `= π r^2`. The goal of audio amplifiers is to reproduce input audio signals at sound-producing output elements, with desired volume and power levels—faithfully, efficiently, and at low distortion. If the thickness of wire is 0.001 meter, and length is 1 m, find its resistivity. Resistance of a conductor is inversely proportional to area of cross section Resistance of a conductor also depends upon nature of material of conductor,temperature of conductor. Resistance of a conductor is inversely proportional to area of cross section. For Example: Silver has lowest resistivity and is the best conductor. So, new resistance is (1/16)th of original resistance. This variable resistance makes resistance bands particularly nice for beginners, those rehabbing from an injury, or who are learning a new exercise and are perfecting form. Contact us on below numbers. Find the equivalent resistance of the combination. 33.A 9Ω resistance is cut into three equal parts and connected in parallel. The resistance of preset resistor is changed using a … Bad conductors are also known as insulators. Example 4: The area of cross section of wire becomes half when its length is stretched to double. Example: Analyzing a more complex resistor circuit. More area of conductor facilitates the flow of electric current through more area and thus decreases the resistance. Electricity of Class 10 Notes - Complete explanation and Notes of Class 10 Science chapter 1 ‘Electricity’.. (a) Two identical resistors each of resistance 10 ohm are connected: (i) in series (ii) in parallel, in turn to a battery of 6V. If the variable resistor has a straight track it is defined in the component by the short form LIN representing a linear track. Stand on the center of a resistance band and hold the ends in each hand, pulling the band taut. Fixed Resistors Variable resistance or Rheostat Types of Resistances Fixed Resistances: Their value does not change under constant physical conditions. This is the cause that thick copper wire creates less resistance to the electric current. Where ρ (rho) is the proportionality constant. Its Components Become our. Resistance of arrangement A is 10 ohm. A conductor has large number of free electrons.When a potential difference is maintained across the ends of conductor,the free electrons move from one end to other end.During their movement,they collide with each other and with atoms of conductor.These collision opposes the movement of electrons  from one end to other end.This opposition to the flow of electrons due to collision is the resistance.More the collision suffered by electron in a conductor,more is the resistance. Conductor The movement of electron gives rise to the flow of current through metals The classification of this can be done based on two important parameters like Resistance (R-ohms) & Power rating (P-Watts). Variable Resistance: The component of an electric circuit which is used to regulate the current; without changing the voltage from the source; is called variable resistance. As current is passed through the metal element in this kettle, resistance causes the metal to get hot and so boils the water. Education Franchise × Contact Us. Usually, the spindle diameter of a variable resistor is 6mm. Resistance is a property of conductor due to which it resists the flow of electric current through it. Solution: Given, Resistivity (ρ) = 10 x 10−8 Ω m, Length ( l ) = 2 m, Diameter = 0.3 mm, Now, Radius of wire `= text(Diameter)/(2) = (0.3 mm) / (2) = 0.15 mm = 1.5 xx 10^-5 m`, Or, `R=(10xx10^-8Ω\xx2m)/(7.65xx10^-9m^2)`. Class Variable: A class variable is an important part of object-oriented programming (OOP) that defines a specific attribute or property for a class and may be referred to as a member variable or static member variable. 1) Connecting wires in electric circuit are made up of Cu and Al. completion of all the aspects of the stages that apply to the final stage of a class 10 building or structure). Contact. Definition of Variable Resistor It is an electronic component. Solved example: Finding current & voltage in a circuit. Filed Under: Class 10, Electricity Tagged With: area of cross section, cause of resistance, connecting wires, filament of an electric bulb, length, nichrome, resistance, resistivity. Electricity of Class 10 Notes, Electricity Class 10 Solutions, Explanation, NCERT Solutions. Tungsten has low resistivity,does not burn even at higher temperature(melting point is very high), 3) Heating elements of electrical appliances like electric iron,heater,toaster,immersion rod are made of nichrome (alloy of Ni,Cr,Fe,Mn). what is the difference between variable resistance and rheostat - Physics - TopperLearning.com | 9ruvgpyy. Practice: Simplifying resistor networks. A variable resistor is a type of resistor whose electrical resistance value can be adjusted on demand. Question 2 How is the resistivity of a material related to the use of that material? It is not changed during normal use of the circuit. 2) Filament of an electric bulb is made up of tungsten metal. It is a variable resistor whose resistance is adjusted during manufacturing or designing of the circuit. Determine the net resistance of the metre in each case. Hard plastic is the one of the best insulators of electricity. Connect wire B between the terminal,note ammeter reading. Defined simply, a Wheatstone Bridge is an electric circuit that is used to measure the electrical resistance of a circuit. Resistivity of a conductor is defined as resistance of the conductor of unit length and unit area of cross-section. They are set at a particular value Variable Resistances: Their resistance can be easily changed by changing area of cross section and length 30. This hindrance is the cause of resistance in the flow of electricity. While the electric potential difference established between the two terminals encourages the movement of charg… Question 5 Why Filament of an electric bulb is made up of tungsten metal? Last Updated on May 4, 2020 By Mrs Shilpi Nagpal Leave a Comment. Potentiometer. R = 1000/101 = 9.9 ohm. Academic Partner . She has started this educational website with the mindset of spreading Free Education to everyone. How the resistance of wire is affected in new condition? Therefore, arrangement B has lower combined resistance. The potentiometer resistance otherwise its value mainly decides how much resistance it gives to the current flow. Many domestic appliances use resistance to transfer electrical energy to heat and light energy. Resistance training is based on the principle that muscles of the body will work to overcome a resistance force when they are required to do so. Solution: Given, Resistance ( R ) = 10 Ω, Length ( l ) = 1 m. Example 3: The resistivity of a metal wire is 10 x 10−8 Ω m at 20°C. Required fields are marked *. This means R will decrease with increase in the area of conductor and vice versa. a)Resistivity of Cu and Al is low(act as a good conductor). Solution : (a) If we take two similar wires of same length and same diameter, one of copper metal and other of nichrome alloy, we will find that the resistance of nichrome wire is about 60 times more than that of the copper wire. Resistors are joined in the circuit in two different methods, i.e., in series and in parallel. (b) Calculate the resistance of an aluminium cable of length 10 km and diameter 2.0 mm if the resistivity of aluminium is 2.7 x 10-8 Ωm. Your email address will not be published. A variable resistor is a resistor of which the electric resistance value can be adjusted. A material whose resistivity is low is a good conductor ie low resistivity means less resistance to flow of current. Answer. A dry person may have a hand-to-foot resistance of 10 5 Ω, whereas the resistance of the human heart is about 10 3 Ω. Rheostat: This is a device which is used in a circuit to provide variable resistance. Such materials are called bad conductors. While some other materials create more hindrance in the flow of electric current, i.e. It is called the electrical resistivity of the material of conductors. For an electron, the journey from terminal to terminal is not a direct route. For example, a 10 ohm resistor connected in parallel with a 5 ohm resistor and a 15 ohm resistor produces 1 / 1/10 + 1/5 + 1/15 ohms of resistance, or 30 / 11 = 2.727 ohms. Reading of ammeter in second case is half that of reading in 1st case. Variable Resistance Specification. Copper wire(A)= length(l) , area of cross section X, copper wire (B)=length (l),area of cross section X. Connect wire A between the terminal,note ammeter reading. A variable resistor has a resistance that can be changed. Question 1 A piece of wire is redrawn  by pulling it until its length is doubles.Compare the new resistance with the original value? Question 3 On what factors does the resistance of a conductor depends? A resistor network that is a combination of parallel and series connections can be broken up into smaller parts that are either one or the other. Example 2: The resistance of an electric wire of an alloy is 10 Ω. Resistivity of a conductor is defined as resistance of the conductor of unit length and unit area of cross-section. The SI unit of resistivity: Since, the SI unit of R is Ω, SI unit of Area is m2 and SI unit of length is m. Hence, Unit of resistivity (ρ) `=(Ωxxm^2)/(m)=Ωm`. 10:00 AM to 7:00 PM IST all days. For Enquiry. Combined resistance of arrangement B is caculated as follows: 1/R = 1/10 + 1/1000 = (100+1)/1000. Question 4 Why connecting wires in an electric circuit are made of Cu and Al? Resistance training (also called strength training or weight training) is the use of resistance to muscular contraction to build the strength, anaerobic endurance and size of skeletal muscles. Resistance of second wire is double than 1st wire. Solution: Let the area of cross section of wire = A. When a variable resistor is used as a potential divider by using 3 … Class 10 building or structure or alteration (including addition) to a class 10 building or structure (except a swimming pool) A notice for inspection must be given by the builder to the building certifier for any stages on the development approval and the final stage (i.e. They have resistivity in the order of 1012 Ω m to 1017 Ω m. Resistivity of materials varies with temperature. This means, Resistance increases with increase in length of the conductor. The electrons encounter resistance - a hindrance to their movement. or own an. A variable resistor is in essence an electro-mechanical transducer and normally works by sliding a contact (wiper) over a resistive element. Flow of electrons in a conductor is electric current. Silver is the best conductor of electricity. It is applied in an electronic circuit for adjusting circuit resistance to control voltage or current of that circuit or part of that circuit. In practical applications, resistors are used to increase or decrease the electric current. Silver has resistivity equal to 1.60 X 10−8 Ω m and copper has resistivity equal to 1.62 X 10−8 Ω m. Rubber and glass are very good insulators. A meter-long piece of large-diameter copper wire may have a resistance of 10 −5 Ω, and superconductors have no resistance at all (they are non-ohmic). Thus, Resistance (R) ∝ length of conductor (l). A fixed resistor has a resistance that remains the same. Audio frequencies range from about 20 Hz to 20 kHz, so the amplifier must have good frequency response over this range (less when driving a band-limited speaker, such as a woofer or a tweeter). Cause of Resistance in a Conductor: Flow of electrons in a conductor is electric current. Need assistance? 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Definition, apt or liable to vary or change ; changeable: variable weather ; variable moods of Resistances Resistances... ) 8356912811. business Enquiry ( North ) 8356912811. business Enquiry ( South ) 8104911739 website with the mindset spreading... & voltage in a what is variable resistance class 10 is inversely proportional to length resistors are used to define a variable resistor a! The combination of resistors in the flow of electric current in a is... Decreased depending on its combinations and connections in a conductor depends: 1 ) resistance of two when! A linear track a Wheatstone Bridge is an electric circuit are made of Science Electricity Answer! A galvanometer with a coil of resistance in a circuit part of that circuit part.