{"id":30234,"date":"2018-08-01T11:00:23","date_gmt":"2018-08-01T11:00:23","guid":{"rendered":"https:\/\/cbselibrary.com\/?p=30234"},"modified":"2020-10-21T12:35:17","modified_gmt":"2020-10-21T07:05:17","slug":"a-new-approach-to-icse-physics-part-2-class-10-solutions-electric-circuits-resistance-ohms-law","status":"publish","type":"post","link":"https:\/\/cbselibrary.com\/a-new-approach-to-icse-physics-part-2-class-10-solutions-electric-circuits-resistance-ohms-law\/","title":{"rendered":"A New Approach to ICSE Physics Part 2 Class 10 Solutions Electric Circuits, Resistance & Ohm\u2019s Law"},"content":{"rendered":"
Exercise – 1<\/strong><\/span><\/p>\n Question 1.<\/strong><\/span> Question 2.<\/strong><\/span> Question 3.<\/strong><\/span> Question 4.<\/strong><\/span> Question 5.<\/strong><\/span> Electric current : Sub multiple units of:<\/strong> Electric current <\/strong>:<\/p>\n Question 6.<\/strong><\/span> Question 7.<\/strong><\/span> Question 8.<\/strong><\/span> Question 9.<\/strong><\/span> Question 10.<\/strong><\/span> Question 11.<\/strong><\/span> Question 12.<\/strong><\/span> Question 13.<\/strong><\/span> Question 14.<\/strong><\/span> Resistivity or sp. Resistance :<\/strong> Multiple choice questions<\/strong><\/span><\/p>\n Tick ( \u2713) the most appropriate option.<\/strong><\/p>\n Question 1.<\/strong><\/span> Question 2.<\/strong><\/span> Question 3.<\/strong><\/span> Question 4.<\/strong><\/span> Question 5.<\/strong><\/span> Question 6.<\/strong><\/span> Question 7.<\/strong><\/span> Numericals on Specific Resistance<\/strong><\/span><\/p>\n Practice Problems : 1<\/strong> Question 2.<\/strong><\/span> Practice Problems : 2<\/strong><\/p>\n Question 1.<\/strong><\/span> Question 2.<\/strong><\/span> Practice Problems : 3<\/p>\n Question 1.<\/strong><\/span> <\/p>\n Question 2.<\/strong><\/span> Exercise – 2<\/strong><\/span><\/p>\n
\nIn which direction conventional current and electronic current flow from a source of electricity ?
\nAnswer:<\/strong><\/span>
\nElectronic current is always in opposite direction to conventional current.<\/p>\n\n
\n\u2234 Electronic current from B to A.
\n<\/li>\n
\n<\/li>\n
\n<\/li>\n<\/ol>\n
\nDefine electric potential. State its practical unit and define it.
\nAnswer:<\/strong><\/span>
\nElectric Potential<\/strong> : \u201cIs the electrical state of a conductor which determines the direction of flow of charrge when two conductors are either in contact or joined by a metallic wire.\u201d
\nOr<\/strong>
\nELECTRIC POTENTIAL \u201cat a point is the work done in moving unit positive charge from infinity to that point in an electric field.
\nS.I. unit is volt.
\nVOLT :<\/strong> \u201cIf work done in moving 1 coulomb of charge from one point to other is 1 joule, the potential-difference between two points is said to be 1 volt.\u201d<\/p>\n
\nDefine quantity of charge. States its practical unit and define it
\nAnswer:<\/strong><\/span>
\nQuality of charge is \u201cThe number of charges (electrons) which drift from a higher to a lower potential is called quantity of charge.\u201d
\nParticle unit of charge is coulomb.
\nCoulomb:<\/strong> \u201cFlow of 6.25 \u00d7 1018<\/sup> electrons through a conductor constitute 1 coulomb.\u201d
\nOr<\/strong>
\n\u201cCharge carried by\u00a0 6.25 \u00d7 1018<\/sup> electrons is called 1 coulomb.\u201d<\/p>\n
\nDefine electric current State its practical unit and define it
\nAnswer:<\/strong><\/span>
\nElectric current: \u201cRate of flow of charge\u201d. I = Q\/t = ne\/t
\nS.I. Unit \u2192 Ampere (A)
\nAmpere :<\/strong> \u201cWhen a charge of 1 coulomb passes in 1 second current flowing is one ampere.\u201d<\/p>\n
\nState two multiples and two submultiples of the unit of electric potential and electric current
\nAnswer:<\/strong><\/span>
\nMultiple units of :<\/strong>
\nElectric potential is<\/p>\n\n
\n<\/strong><\/p>\n\n
\nElectric potential:<\/strong><\/p>\n\n
\n
\nWhat do you understand by the terms potential difference? State its practical unit
\nAnswer:<\/strong><\/span>
\nPotential difference: \u201cIs the amount of work done in moving a unit positive charge from one point to other.\u201d Practical unit – volt.<\/p>\n
\nDefine
\n(a)<\/strong> open electric circuit
\n(b)<\/strong> closed electric circuit.
\nAnswer:<\/strong><\/span>
\n(a) Open electric circuit :<\/strong> \u201cAn electric circuit in which low of current stops, because of an open switch is called an open_electric circuit.
\n(b) Closed electric circuit :<\/strong> \u201cAn electric circuit in which a current flows continuously, because the switch is closed is called a closed electric .
\n<\/p>\n
\nWhat do you understand by the term electric resistance? state its practical unit.
\nAnswer:<\/strong><\/span>
\n\u201cThe obstruction offered to the flow of current by a conductor (wire) is called its RESISTANCE.\u201d
\nS.l. UNIT \u2014 is 1\/OHM or (Ohm)-1<\/sup><\/p>\n
\nWhat do you understand by the term electric conductance? State its practical unil
\nAnswer:<\/strong><\/span>
\n\u201cThe reciprocal of resistance is called electric CONDUCTANCE\u201d. i.e.
\nConductance = 1\/Resistance
\nS.l. Unit of Conductance \u03a9-1<\/sup> or OHM-1<\/sup><\/p>\n
\nWhat is a superconductor ? Name two materials and the temperature at which they become superconductors.
\nAnswer:<\/strong><\/span>
\nSUPER CONDUCTOR : \u201cThe substances which lose resistance when they are cooled to very low temperature (nearly absolute zero) are called super conductors, e.g. mercury at 4.12 k, LEAD. TIN, VANADIUM etc. and this phenomenon is called SUPER CONDUCTIVITY. The temperature at which they become super-conductors is called CRITICAL TEMPERATURE.<\/p>\n
\nState the laws of resistance.
\nAnswer:<\/strong><\/span>
\nLaws of resistance :<\/strong><\/p>\n\n
\nDefine specific resistance and state its unit in CGS and SI system.
\nAnswer:<\/strong><\/span>
\nSpecific resistance:<\/strong> \u201cIs the resistance of a wire of that material of unit length and unit area of cross-section.\u201d
\nUnit:<\/strong>
\nIn C.G.S. system \u2192 [\u03a9 – cm] ohm – cm
\nIn S.I. system \u2192 [\u03a9 – m] ohm – metre.<\/p>\n
\nName two materials in each case whose resistance
\n(a)<\/strong> increases,
\n(b)<\/strong> remains the same and
\n(c)<\/strong> decreases with the rise in temperature.
\nAnswer:<\/strong><\/span>
\nTwo materials:<\/strong><\/p>\n\n
\nGive two differences between the electric resistance and electric specific resistance of a material
\nAnswer:<\/strong><\/span>
\nTwo differences between resistance and sp. resistance.
\nResistance :<\/strong><\/p>\n\n
\nS.I. unit [\u03a9-m] ohm. metre. It is measured as the resistance offered by a conductor of unit length and unit area of cross-section.<\/p>\n
\nThe graph between V\/I for a conductor is a straight line. The slope of the graph represents :
\n(a)<\/strong> resistivity
\n(b)<\/strong> resistance
\n(c)<\/strong> electric potential
\n(d)<\/strong> none of these
\nAnswer:<\/strong><\/span>
\n(b)<\/strong> resistance<\/p>\n
\nTwo conductors A and B have 500 and 100 units of . negative charge when the conductors are connected by
\nan electric wire the conventional current flows from :
\n(a)<\/strong> A to B
\n(b)<\/strong> B to A
\n(c)<\/strong> Current does not flow
\n(d)<\/strong> none of these
\nAnswer:<\/strong><\/span>
\n(b)<\/strong> B to A<\/p>\n
\nA conductor at 4.2 K is found to offer no resistance. Such a conductor is called
\n(a)<\/strong> zero conductor
\n(b)<\/strong> superconductor
\n(c)<\/strong> absolute conductor
\n(d)<\/strong> none of these
\nAnswer:<\/strong><\/span>
\n(b)<\/strong> superconductor<\/p>\n
\nWhich of the following is non-ohmic resistance ?
\n(a)<\/strong> Copper wire
\n(b)<\/strong> Brass wire
\n(c)<\/strong> Copper wire wound on an electromagnet
\n(d)<\/strong> Constantan wire
\nAnswer:<\/strong><\/span>
\n(b)<\/strong> Brass wire<\/p>\n
\nWhich of the following an ohmic resistance ?
\n(a)<\/strong> Diode valve
\n(b)<\/strong> Filament of a bulb
\n(c)<\/strong> Carbon are light
\n(d)<\/strong> Manganin wire
\nAnswer:<\/strong><\/span>
\n(d)<\/strong> Manganin wire<\/p>\n
\nA conductor has a resistivity of 2.63 \u00d7 10-8<\/sup> \u03a9 m at 20\u00b0 C. If the temperature of conductor is raised to 200\u00b0C, its resistivity will :
\n(a)<\/strong> increase
\n(b)<\/strong> decrease
\n(c)<\/strong> remain unaffected
\n(d)<\/strong> none of these
\nAnswer:<\/strong><\/span>
\n(a)<\/strong> increase<\/p>\n
\nAmongst the following substance, the resistance will decrease with the increase in temperature in case of:
\n(a)\u00a0<\/strong>copper
\n(b)<\/strong> carbon
\n(c)\u00a0<\/strong>brass
\n(d)<\/strong> nichrome
\nAnswer:<\/strong><\/span>
\n(b)<\/strong> carbon<\/p>\n
\nQuestion 1.<\/strong><\/span>
\nA wire of resistance 4.5 \u03a9 and length 150 cm, has an area of cross-section of 0.04 cm-2<\/sup>. Calculate sp. resistance of the wire.
\nAnswer:<\/strong><\/span>
\n<\/p>\n
\nA wire of length 40 cm and area of cross-section 0.1 mm2<\/sup> has a resistance of 0.8 fl Calculate sp. resistance of the wire.
\nAnswer:<\/strong><\/span>
\nI = 40 cm, area of cross-section a = 0.1 m m2<\/sup> = 0.1\/100 c m2<\/sup> R = 0.8 \u03a9
\n<\/p>\n
\nResistance of a conductor of length 75 cm is 3.25 \u03a9. Calculate the length of a similar conductor, whose resistance is 13.25\u03a9.
\nAnswer:<\/strong><\/span>
\n<\/p>\n
\nA conductor of length 85 cm has a resistance of 3.750. Calculate the resistance of a similar conductor of length 540 cm.
\nAnswer:<\/strong><\/span>
\n<\/p>\n
\nA resistance wire made from German silver has a resistance of 4.250. Calculate the resistance of another wire, made from same material, such that its length increases by 4 times and area of cross-section decreases by three times.
\nAnswer:<\/strong><\/span>
\n<\/p>\n
\nA nichrome wire of length l and area of cross-section a\/ 4 has a resistance R. Another nichrome wire of length 31 and area of cross-section a\/2 has a resistance of R1<\/sub> Find the ratio of R, : R.
\nAnswer:
\n<\/strong><\/span>As both the wire are made of same material, have same sp. resistance
\n<\/p>\n