JEE Exam > JEE Notes > Physics for JEE Main & Advanced > Solved Example: Current Electricity
Solved Example: Current Electricity | Physics for JEE Main & Advanced PDF Download
| Download, print and study this document offline |
Please wait while the PDF view is loading
Page 1 JEE Solved Examples on Current Electricity JEE Mains Q1: In the Bohr's model of hydrogen atom, the electrons moves around the nucleus in a circular orbit of a radius ?? × ???? -???? metre. It's time period is ?? . ?? × ???? -???? ?????? . The current associated is (a) Zero (b) ?? . ?? × ???? -???? ?? (c) ?? . ???? ?? (d) ?? . ???? × ???? -?? ?? Ans: (d) ?? = ?? ?? = 1.6×10 -19 1.5×10 -16 = 1.07 × 10 -3 A Q2: A copper wire of length ?? ?? and radius ?? ???? is joined in series with an iron wire of length ?? ?? and radius ?? ???? and a current is passed through the wire. The ratio of current densities in the copper and iron wire is (a) ???? : ?? (b) ?? : ?? (c) ?? : ?? (d) ?? : ?? Ans: (b) We know ?? = ?? ?? when ?? = constant ?? ? 1 ?? ? ?? ?? ?? ?? = ?? ?? ?? ?? = ( ?? ?? ?? ?? ) 2 = ( 3 1 ) 2 = 9 1 Q3: 8 In a wire of circular cross-section with radius ?? , free electrons travel with a drift velocity ?? , when a current ?? flows through the wire. What is the current in another wire of half the radius and of the some material when the drift velocity is ?? ?? (a) ?? ?? (b) ?? (c) ?? /?? (d) ?? /?? Ans: (c) ?? = ?????? ?? ?? = ?????? ?? 2 ?? and ?? 2 = ?????? ( ?? 2 ) 2 · 2?? = ?????? · 2 ?? 2 = ?? 2 Q4: Two wires ?? and ?? of the same material, having radii in the ratio ?? : ?? and carry currents in the ratio ?? : ?? . The ratio of drift speeds of electrons in ?? and ?? is (a) ???? : ?? (b) ?? : ???? (c) ?? : ?? (d) ?? : ?? Ans: (a) As ?? = ?????? ?? ?? ? ?? 1 ?? 2 = ?? 1 ?? 2 × ?? ?? 1 ?? ?? 2 = ?? 1 2 ?? 2 2 · ?? ?? 1 ?? ?? 2 ? ?? ?? 1 ?? ?? 2 = 16 1 Page 2 JEE Solved Examples on Current Electricity JEE Mains Q1: In the Bohr's model of hydrogen atom, the electrons moves around the nucleus in a circular orbit of a radius ?? × ???? -???? metre. It's time period is ?? . ?? × ???? -???? ?????? . The current associated is (a) Zero (b) ?? . ?? × ???? -???? ?? (c) ?? . ???? ?? (d) ?? . ???? × ???? -?? ?? Ans: (d) ?? = ?? ?? = 1.6×10 -19 1.5×10 -16 = 1.07 × 10 -3 A Q2: A copper wire of length ?? ?? and radius ?? ???? is joined in series with an iron wire of length ?? ?? and radius ?? ???? and a current is passed through the wire. The ratio of current densities in the copper and iron wire is (a) ???? : ?? (b) ?? : ?? (c) ?? : ?? (d) ?? : ?? Ans: (b) We know ?? = ?? ?? when ?? = constant ?? ? 1 ?? ? ?? ?? ?? ?? = ?? ?? ?? ?? = ( ?? ?? ?? ?? ) 2 = ( 3 1 ) 2 = 9 1 Q3: 8 In a wire of circular cross-section with radius ?? , free electrons travel with a drift velocity ?? , when a current ?? flows through the wire. What is the current in another wire of half the radius and of the some material when the drift velocity is ?? ?? (a) ?? ?? (b) ?? (c) ?? /?? (d) ?? /?? Ans: (c) ?? = ?????? ?? ?? = ?????? ?? 2 ?? and ?? 2 = ?????? ( ?? 2 ) 2 · 2?? = ?????? · 2 ?? 2 = ?? 2 Q4: Two wires ?? and ?? of the same material, having radii in the ratio ?? : ?? and carry currents in the ratio ?? : ?? . The ratio of drift speeds of electrons in ?? and ?? is (a) ???? : ?? (b) ?? : ???? (c) ?? : ?? (d) ?? : ?? Ans: (a) As ?? = ?????? ?? ?? ? ?? 1 ?? 2 = ?? 1 ?? 2 × ?? ?? 1 ?? ?? 2 = ?? 1 2 ?? 2 2 · ?? ?? 1 ?? ?? 2 ? ?? ?? 1 ?? ?? 2 = 16 1 Q5: Two wires of resistance ?? ?? and ?? ?? have temperature co-efficient of resistance ?? ?? and ?? ?? respectively. These are joined in series. The effective temperature co -efficient of resistance is (a) ?? ?? +?? ?? ?? (b) v ?? ?? ?? ?? (c) ?? ?? ?? ?? +?? ?? ?? ?? ?? ?? +?? ?? (d) v?? ?? ?? ?? ?? ?? ?? ?? v?? ?? ?? +?? ?? ?? Ans: (c) Suppose at ?? ° C resistances of the two wires becomes ?? 1?? and ?? 2?? respectively and equivalent resistance becomes ?? ?? . In series grouping ?? ?? = ?? 1?? + ?? 2?? , also ?? 1?? = ?? 1 (1 + ?? 1 ?? ) and ?? 2?? = ?? 2 (1 + ?? 2 ?? ) ?? ?? = ?? 1 (1 + ?? 1 ?? ) + ?? 2 (1 + ?? 2 ?? ) = (?? 1 + ?? 2 ) + (?? 1 ?? 1 + ?? 2 ?? 2 )?? = (?? 1 + ?? 2 )[1 + ?? 1 ?? 1 + ?? 2 ?? 2 ?? 1 + ?? 2 ?? ] . Hence effective temperature co -efficient is ?? 1 ?? 1 +?? 2 ?? 2 ?? 1 +?? 2 . Q6: A rod of certain metal is ?? ?? long and ?? . ?? ???? in diameter. It's resistance is ?? × ???? -?? ?? . A disc of the same metal is ?? ???? thick and ?? ???? in diameter, what is the resistance between it's circular faces. (a) ?? . ???? × ???? -?? ?? (b) ?? . ?? × ???? -?? ?? (c) ?? . ???? × ???? -?? ?? (d) ?? . ?? × ???? -?? ?? Ans: (b) By using ?? = ?? · ?? ?? ; ?? disc ?? rod = ?? disc ?? rod × ?? rod ?? disc ? ?? disc 3×10 -3 = 10 -3 1 × ?? (0.3×10 -2 ) 2 ?? (10 -2 ) 2 ? ?? disc = 2.7 × 10 -7 O. Q7: If a copper wire is stretched to make it ?? . ?? % longer, the percentage increase in resistance will be (a) 0.2 (b) 2 (c) 1 (d) 0.1 Ans: (a) In case of streching ?? ? ?? 2 So ??? ?? = 2 ??? ?? = 2 × 0.1 = 0.2 Q8: Equal potentials are applied on an iron and copper wire of same length. In order to have same current flow in the wire, the ratio ( ?? iron ?? copper ) of their radii must be [Given that specific resistance of iron = ?? . ?? × ???? -?? ???? and that of copper = ?? . ?? × ???? -?? ???? ] (a) About 1.2 (b) About 2.4 (c) About 3.6 (d) About 4.8 Page 3 JEE Solved Examples on Current Electricity JEE Mains Q1: In the Bohr's model of hydrogen atom, the electrons moves around the nucleus in a circular orbit of a radius ?? × ???? -???? metre. It's time period is ?? . ?? × ???? -???? ?????? . The current associated is (a) Zero (b) ?? . ?? × ???? -???? ?? (c) ?? . ???? ?? (d) ?? . ???? × ???? -?? ?? Ans: (d) ?? = ?? ?? = 1.6×10 -19 1.5×10 -16 = 1.07 × 10 -3 A Q2: A copper wire of length ?? ?? and radius ?? ???? is joined in series with an iron wire of length ?? ?? and radius ?? ???? and a current is passed through the wire. The ratio of current densities in the copper and iron wire is (a) ???? : ?? (b) ?? : ?? (c) ?? : ?? (d) ?? : ?? Ans: (b) We know ?? = ?? ?? when ?? = constant ?? ? 1 ?? ? ?? ?? ?? ?? = ?? ?? ?? ?? = ( ?? ?? ?? ?? ) 2 = ( 3 1 ) 2 = 9 1 Q3: 8 In a wire of circular cross-section with radius ?? , free electrons travel with a drift velocity ?? , when a current ?? flows through the wire. What is the current in another wire of half the radius and of the some material when the drift velocity is ?? ?? (a) ?? ?? (b) ?? (c) ?? /?? (d) ?? /?? Ans: (c) ?? = ?????? ?? ?? = ?????? ?? 2 ?? and ?? 2 = ?????? ( ?? 2 ) 2 · 2?? = ?????? · 2 ?? 2 = ?? 2 Q4: Two wires ?? and ?? of the same material, having radii in the ratio ?? : ?? and carry currents in the ratio ?? : ?? . The ratio of drift speeds of electrons in ?? and ?? is (a) ???? : ?? (b) ?? : ???? (c) ?? : ?? (d) ?? : ?? Ans: (a) As ?? = ?????? ?? ?? ? ?? 1 ?? 2 = ?? 1 ?? 2 × ?? ?? 1 ?? ?? 2 = ?? 1 2 ?? 2 2 · ?? ?? 1 ?? ?? 2 ? ?? ?? 1 ?? ?? 2 = 16 1 Q5: Two wires of resistance ?? ?? and ?? ?? have temperature co-efficient of resistance ?? ?? and ?? ?? respectively. These are joined in series. The effective temperature co -efficient of resistance is (a) ?? ?? +?? ?? ?? (b) v ?? ?? ?? ?? (c) ?? ?? ?? ?? +?? ?? ?? ?? ?? ?? +?? ?? (d) v?? ?? ?? ?? ?? ?? ?? ?? v?? ?? ?? +?? ?? ?? Ans: (c) Suppose at ?? ° C resistances of the two wires becomes ?? 1?? and ?? 2?? respectively and equivalent resistance becomes ?? ?? . In series grouping ?? ?? = ?? 1?? + ?? 2?? , also ?? 1?? = ?? 1 (1 + ?? 1 ?? ) and ?? 2?? = ?? 2 (1 + ?? 2 ?? ) ?? ?? = ?? 1 (1 + ?? 1 ?? ) + ?? 2 (1 + ?? 2 ?? ) = (?? 1 + ?? 2 ) + (?? 1 ?? 1 + ?? 2 ?? 2 )?? = (?? 1 + ?? 2 )[1 + ?? 1 ?? 1 + ?? 2 ?? 2 ?? 1 + ?? 2 ?? ] . Hence effective temperature co -efficient is ?? 1 ?? 1 +?? 2 ?? 2 ?? 1 +?? 2 . Q6: A rod of certain metal is ?? ?? long and ?? . ?? ???? in diameter. It's resistance is ?? × ???? -?? ?? . A disc of the same metal is ?? ???? thick and ?? ???? in diameter, what is the resistance between it's circular faces. (a) ?? . ???? × ???? -?? ?? (b) ?? . ?? × ???? -?? ?? (c) ?? . ???? × ???? -?? ?? (d) ?? . ?? × ???? -?? ?? Ans: (b) By using ?? = ?? · ?? ?? ; ?? disc ?? rod = ?? disc ?? rod × ?? rod ?? disc ? ?? disc 3×10 -3 = 10 -3 1 × ?? (0.3×10 -2 ) 2 ?? (10 -2 ) 2 ? ?? disc = 2.7 × 10 -7 O. Q7: If a copper wire is stretched to make it ?? . ?? % longer, the percentage increase in resistance will be (a) 0.2 (b) 2 (c) 1 (d) 0.1 Ans: (a) In case of streching ?? ? ?? 2 So ??? ?? = 2 ??? ?? = 2 × 0.1 = 0.2 Q8: Equal potentials are applied on an iron and copper wire of same length. In order to have same current flow in the wire, the ratio ( ?? iron ?? copper ) of their radii must be [Given that specific resistance of iron = ?? . ?? × ???? -?? ???? and that of copper = ?? . ?? × ???? -?? ???? ] (a) About 1.2 (b) About 2.4 (c) About 3.6 (d) About 4.8 Ans: (b) ?? = constant., ?? = constant. So ?? = constant ? ?? ?? ?? ?? ?? ?? = ?? ???? ?? ???? ?? ???? ? ?? ?? ?? ?? ?? ?? 2 = ?? ???? ?? ???? ?? ???? 2 ? ?? ?? ?? ???? = v ?? ?? ?? ???? = v 1.0 × 10 -7 1.7 × 10 -8 = v 100 17 ˜ 2.4 Q9: Masses of three wires are in the ratio ?? : ?? : ?? and their lengths are in the ratio ?? : ?? : ?? . The ratio of their electrical resistance is (a) ?? : ?? : ?? (b) ?? : ?? : ?? (c) ?? : ???? : ?????? (d) ?????? : ???? : ?? Ans: (d) ?? = ?? ?? ?? = ?? ?? 2 ?? = ?? ?? 2 ?? ?? (? ?? = ?? ?? ) ?? 1 : ?? 2 : ?? 3 = ?? 1 2 ?? 1 : ?? 2 2 ?? 2 : ?? 3 2 ?? 3 = 25: 9 3 : 1 5 = 125: 15: 1 Q10: Two resistance ?? ?? and ?? ?? provides series to parallel equivalents as ?? ?? then the correct relationship is (a) ( ?? ?? ?? ?? ) ?? + ( ?? ?? ?? ?? ) ?? = ?? ?? (b) ( ?? ?? ?? ?? ) ?? /?? + ( ?? ?? ?? ?? ) ?? /?? = ?? ?? /?? (c) ( ?? ?? ?? ?? ) + ( ?? ?? ?? ?? ) = ?? (d) ( ?? ?? ?? ?? ) ?? /?? + ( ?? ?? ?? ?? ) ?? /?? = ?? ?? /?? Ans: (d) Series resistance ?? ?? = ?? 1 + ?? 2 and parallel resistance ?? ?? = ?? 1 ?? 2 ?? 1 +?? 2 ? ?? ?? ?? ?? = (?? 1 +?? 2 ) 2 ?? 1 ?? 2 = ?? ? ?? 1 + ?? 2 v?? 1 ?? 2 = v ?? ? v?? 1 2 v?? 1 ?? 2 + v?? 2 2 v?? 1 ?? 2 = v ?? ? v ?? 1 ?? 2 + v ?? 2 ?? 1 = v ?? Page 4 JEE Solved Examples on Current Electricity JEE Mains Q1: In the Bohr's model of hydrogen atom, the electrons moves around the nucleus in a circular orbit of a radius ?? × ???? -???? metre. It's time period is ?? . ?? × ???? -???? ?????? . The current associated is (a) Zero (b) ?? . ?? × ???? -???? ?? (c) ?? . ???? ?? (d) ?? . ???? × ???? -?? ?? Ans: (d) ?? = ?? ?? = 1.6×10 -19 1.5×10 -16 = 1.07 × 10 -3 A Q2: A copper wire of length ?? ?? and radius ?? ???? is joined in series with an iron wire of length ?? ?? and radius ?? ???? and a current is passed through the wire. The ratio of current densities in the copper and iron wire is (a) ???? : ?? (b) ?? : ?? (c) ?? : ?? (d) ?? : ?? Ans: (b) We know ?? = ?? ?? when ?? = constant ?? ? 1 ?? ? ?? ?? ?? ?? = ?? ?? ?? ?? = ( ?? ?? ?? ?? ) 2 = ( 3 1 ) 2 = 9 1 Q3: 8 In a wire of circular cross-section with radius ?? , free electrons travel with a drift velocity ?? , when a current ?? flows through the wire. What is the current in another wire of half the radius and of the some material when the drift velocity is ?? ?? (a) ?? ?? (b) ?? (c) ?? /?? (d) ?? /?? Ans: (c) ?? = ?????? ?? ?? = ?????? ?? 2 ?? and ?? 2 = ?????? ( ?? 2 ) 2 · 2?? = ?????? · 2 ?? 2 = ?? 2 Q4: Two wires ?? and ?? of the same material, having radii in the ratio ?? : ?? and carry currents in the ratio ?? : ?? . The ratio of drift speeds of electrons in ?? and ?? is (a) ???? : ?? (b) ?? : ???? (c) ?? : ?? (d) ?? : ?? Ans: (a) As ?? = ?????? ?? ?? ? ?? 1 ?? 2 = ?? 1 ?? 2 × ?? ?? 1 ?? ?? 2 = ?? 1 2 ?? 2 2 · ?? ?? 1 ?? ?? 2 ? ?? ?? 1 ?? ?? 2 = 16 1 Q5: Two wires of resistance ?? ?? and ?? ?? have temperature co-efficient of resistance ?? ?? and ?? ?? respectively. These are joined in series. The effective temperature co -efficient of resistance is (a) ?? ?? +?? ?? ?? (b) v ?? ?? ?? ?? (c) ?? ?? ?? ?? +?? ?? ?? ?? ?? ?? +?? ?? (d) v?? ?? ?? ?? ?? ?? ?? ?? v?? ?? ?? +?? ?? ?? Ans: (c) Suppose at ?? ° C resistances of the two wires becomes ?? 1?? and ?? 2?? respectively and equivalent resistance becomes ?? ?? . In series grouping ?? ?? = ?? 1?? + ?? 2?? , also ?? 1?? = ?? 1 (1 + ?? 1 ?? ) and ?? 2?? = ?? 2 (1 + ?? 2 ?? ) ?? ?? = ?? 1 (1 + ?? 1 ?? ) + ?? 2 (1 + ?? 2 ?? ) = (?? 1 + ?? 2 ) + (?? 1 ?? 1 + ?? 2 ?? 2 )?? = (?? 1 + ?? 2 )[1 + ?? 1 ?? 1 + ?? 2 ?? 2 ?? 1 + ?? 2 ?? ] . Hence effective temperature co -efficient is ?? 1 ?? 1 +?? 2 ?? 2 ?? 1 +?? 2 . Q6: A rod of certain metal is ?? ?? long and ?? . ?? ???? in diameter. It's resistance is ?? × ???? -?? ?? . A disc of the same metal is ?? ???? thick and ?? ???? in diameter, what is the resistance between it's circular faces. (a) ?? . ???? × ???? -?? ?? (b) ?? . ?? × ???? -?? ?? (c) ?? . ???? × ???? -?? ?? (d) ?? . ?? × ???? -?? ?? Ans: (b) By using ?? = ?? · ?? ?? ; ?? disc ?? rod = ?? disc ?? rod × ?? rod ?? disc ? ?? disc 3×10 -3 = 10 -3 1 × ?? (0.3×10 -2 ) 2 ?? (10 -2 ) 2 ? ?? disc = 2.7 × 10 -7 O. Q7: If a copper wire is stretched to make it ?? . ?? % longer, the percentage increase in resistance will be (a) 0.2 (b) 2 (c) 1 (d) 0.1 Ans: (a) In case of streching ?? ? ?? 2 So ??? ?? = 2 ??? ?? = 2 × 0.1 = 0.2 Q8: Equal potentials are applied on an iron and copper wire of same length. In order to have same current flow in the wire, the ratio ( ?? iron ?? copper ) of their radii must be [Given that specific resistance of iron = ?? . ?? × ???? -?? ???? and that of copper = ?? . ?? × ???? -?? ???? ] (a) About 1.2 (b) About 2.4 (c) About 3.6 (d) About 4.8 Ans: (b) ?? = constant., ?? = constant. So ?? = constant ? ?? ?? ?? ?? ?? ?? = ?? ???? ?? ???? ?? ???? ? ?? ?? ?? ?? ?? ?? 2 = ?? ???? ?? ???? ?? ???? 2 ? ?? ?? ?? ???? = v ?? ?? ?? ???? = v 1.0 × 10 -7 1.7 × 10 -8 = v 100 17 ˜ 2.4 Q9: Masses of three wires are in the ratio ?? : ?? : ?? and their lengths are in the ratio ?? : ?? : ?? . The ratio of their electrical resistance is (a) ?? : ?? : ?? (b) ?? : ?? : ?? (c) ?? : ???? : ?????? (d) ?????? : ???? : ?? Ans: (d) ?? = ?? ?? ?? = ?? ?? 2 ?? = ?? ?? 2 ?? ?? (? ?? = ?? ?? ) ?? 1 : ?? 2 : ?? 3 = ?? 1 2 ?? 1 : ?? 2 2 ?? 2 : ?? 3 2 ?? 3 = 25: 9 3 : 1 5 = 125: 15: 1 Q10: Two resistance ?? ?? and ?? ?? provides series to parallel equivalents as ?? ?? then the correct relationship is (a) ( ?? ?? ?? ?? ) ?? + ( ?? ?? ?? ?? ) ?? = ?? ?? (b) ( ?? ?? ?? ?? ) ?? /?? + ( ?? ?? ?? ?? ) ?? /?? = ?? ?? /?? (c) ( ?? ?? ?? ?? ) + ( ?? ?? ?? ?? ) = ?? (d) ( ?? ?? ?? ?? ) ?? /?? + ( ?? ?? ?? ?? ) ?? /?? = ?? ?? /?? Ans: (d) Series resistance ?? ?? = ?? 1 + ?? 2 and parallel resistance ?? ?? = ?? 1 ?? 2 ?? 1 +?? 2 ? ?? ?? ?? ?? = (?? 1 +?? 2 ) 2 ?? 1 ?? 2 = ?? ? ?? 1 + ?? 2 v?? 1 ?? 2 = v ?? ? v?? 1 2 v?? 1 ?? 2 + v?? 2 2 v?? 1 ?? 2 = v ?? ? v ?? 1 ?? 2 + v ?? 2 ?? 1 = v ?? Q11: Five resistances are combined according to the figure. The equivalent resistance between the point ?? and ?? will be (a) ?????? (b) ?????? (c) ?????? (d) ?????? Ans: (a) The equivalent circuit of above can be drawn as Which is a balanced wheatstone bridge. So current through ???? is zero. So 1 ?? = 1 20 + 1 20 = 1 10 ? ?? = 10O Q12: What will be the equivalent resistance of circuit shown in figure between points ?? and ?? [c (a) ?????? (b) ?????? (c) ?????? (d) ?????? Ans: (c) The equivalent circuit of above fig between ?? and ?? can be drawn as So ?? ???? = 10 + 10 + 10 = 30O Page 5 JEE Solved Examples on Current Electricity JEE Mains Q1: In the Bohr's model of hydrogen atom, the electrons moves around the nucleus in a circular orbit of a radius ?? × ???? -???? metre. It's time period is ?? . ?? × ???? -???? ?????? . The current associated is (a) Zero (b) ?? . ?? × ???? -???? ?? (c) ?? . ???? ?? (d) ?? . ???? × ???? -?? ?? Ans: (d) ?? = ?? ?? = 1.6×10 -19 1.5×10 -16 = 1.07 × 10 -3 A Q2: A copper wire of length ?? ?? and radius ?? ???? is joined in series with an iron wire of length ?? ?? and radius ?? ???? and a current is passed through the wire. The ratio of current densities in the copper and iron wire is (a) ???? : ?? (b) ?? : ?? (c) ?? : ?? (d) ?? : ?? Ans: (b) We know ?? = ?? ?? when ?? = constant ?? ? 1 ?? ? ?? ?? ?? ?? = ?? ?? ?? ?? = ( ?? ?? ?? ?? ) 2 = ( 3 1 ) 2 = 9 1 Q3: 8 In a wire of circular cross-section with radius ?? , free electrons travel with a drift velocity ?? , when a current ?? flows through the wire. What is the current in another wire of half the radius and of the some material when the drift velocity is ?? ?? (a) ?? ?? (b) ?? (c) ?? /?? (d) ?? /?? Ans: (c) ?? = ?????? ?? ?? = ?????? ?? 2 ?? and ?? 2 = ?????? ( ?? 2 ) 2 · 2?? = ?????? · 2 ?? 2 = ?? 2 Q4: Two wires ?? and ?? of the same material, having radii in the ratio ?? : ?? and carry currents in the ratio ?? : ?? . The ratio of drift speeds of electrons in ?? and ?? is (a) ???? : ?? (b) ?? : ???? (c) ?? : ?? (d) ?? : ?? Ans: (a) As ?? = ?????? ?? ?? ? ?? 1 ?? 2 = ?? 1 ?? 2 × ?? ?? 1 ?? ?? 2 = ?? 1 2 ?? 2 2 · ?? ?? 1 ?? ?? 2 ? ?? ?? 1 ?? ?? 2 = 16 1 Q5: Two wires of resistance ?? ?? and ?? ?? have temperature co-efficient of resistance ?? ?? and ?? ?? respectively. These are joined in series. The effective temperature co -efficient of resistance is (a) ?? ?? +?? ?? ?? (b) v ?? ?? ?? ?? (c) ?? ?? ?? ?? +?? ?? ?? ?? ?? ?? +?? ?? (d) v?? ?? ?? ?? ?? ?? ?? ?? v?? ?? ?? +?? ?? ?? Ans: (c) Suppose at ?? ° C resistances of the two wires becomes ?? 1?? and ?? 2?? respectively and equivalent resistance becomes ?? ?? . In series grouping ?? ?? = ?? 1?? + ?? 2?? , also ?? 1?? = ?? 1 (1 + ?? 1 ?? ) and ?? 2?? = ?? 2 (1 + ?? 2 ?? ) ?? ?? = ?? 1 (1 + ?? 1 ?? ) + ?? 2 (1 + ?? 2 ?? ) = (?? 1 + ?? 2 ) + (?? 1 ?? 1 + ?? 2 ?? 2 )?? = (?? 1 + ?? 2 )[1 + ?? 1 ?? 1 + ?? 2 ?? 2 ?? 1 + ?? 2 ?? ] . Hence effective temperature co -efficient is ?? 1 ?? 1 +?? 2 ?? 2 ?? 1 +?? 2 . Q6: A rod of certain metal is ?? ?? long and ?? . ?? ???? in diameter. It's resistance is ?? × ???? -?? ?? . A disc of the same metal is ?? ???? thick and ?? ???? in diameter, what is the resistance between it's circular faces. (a) ?? . ???? × ???? -?? ?? (b) ?? . ?? × ???? -?? ?? (c) ?? . ???? × ???? -?? ?? (d) ?? . ?? × ???? -?? ?? Ans: (b) By using ?? = ?? · ?? ?? ; ?? disc ?? rod = ?? disc ?? rod × ?? rod ?? disc ? ?? disc 3×10 -3 = 10 -3 1 × ?? (0.3×10 -2 ) 2 ?? (10 -2 ) 2 ? ?? disc = 2.7 × 10 -7 O. Q7: If a copper wire is stretched to make it ?? . ?? % longer, the percentage increase in resistance will be (a) 0.2 (b) 2 (c) 1 (d) 0.1 Ans: (a) In case of streching ?? ? ?? 2 So ??? ?? = 2 ??? ?? = 2 × 0.1 = 0.2 Q8: Equal potentials are applied on an iron and copper wire of same length. In order to have same current flow in the wire, the ratio ( ?? iron ?? copper ) of their radii must be [Given that specific resistance of iron = ?? . ?? × ???? -?? ???? and that of copper = ?? . ?? × ???? -?? ???? ] (a) About 1.2 (b) About 2.4 (c) About 3.6 (d) About 4.8 Ans: (b) ?? = constant., ?? = constant. So ?? = constant ? ?? ?? ?? ?? ?? ?? = ?? ???? ?? ???? ?? ???? ? ?? ?? ?? ?? ?? ?? 2 = ?? ???? ?? ???? ?? ???? 2 ? ?? ?? ?? ???? = v ?? ?? ?? ???? = v 1.0 × 10 -7 1.7 × 10 -8 = v 100 17 ˜ 2.4 Q9: Masses of three wires are in the ratio ?? : ?? : ?? and their lengths are in the ratio ?? : ?? : ?? . The ratio of their electrical resistance is (a) ?? : ?? : ?? (b) ?? : ?? : ?? (c) ?? : ???? : ?????? (d) ?????? : ???? : ?? Ans: (d) ?? = ?? ?? ?? = ?? ?? 2 ?? = ?? ?? 2 ?? ?? (? ?? = ?? ?? ) ?? 1 : ?? 2 : ?? 3 = ?? 1 2 ?? 1 : ?? 2 2 ?? 2 : ?? 3 2 ?? 3 = 25: 9 3 : 1 5 = 125: 15: 1 Q10: Two resistance ?? ?? and ?? ?? provides series to parallel equivalents as ?? ?? then the correct relationship is (a) ( ?? ?? ?? ?? ) ?? + ( ?? ?? ?? ?? ) ?? = ?? ?? (b) ( ?? ?? ?? ?? ) ?? /?? + ( ?? ?? ?? ?? ) ?? /?? = ?? ?? /?? (c) ( ?? ?? ?? ?? ) + ( ?? ?? ?? ?? ) = ?? (d) ( ?? ?? ?? ?? ) ?? /?? + ( ?? ?? ?? ?? ) ?? /?? = ?? ?? /?? Ans: (d) Series resistance ?? ?? = ?? 1 + ?? 2 and parallel resistance ?? ?? = ?? 1 ?? 2 ?? 1 +?? 2 ? ?? ?? ?? ?? = (?? 1 +?? 2 ) 2 ?? 1 ?? 2 = ?? ? ?? 1 + ?? 2 v?? 1 ?? 2 = v ?? ? v?? 1 2 v?? 1 ?? 2 + v?? 2 2 v?? 1 ?? 2 = v ?? ? v ?? 1 ?? 2 + v ?? 2 ?? 1 = v ?? Q11: Five resistances are combined according to the figure. The equivalent resistance between the point ?? and ?? will be (a) ?????? (b) ?????? (c) ?????? (d) ?????? Ans: (a) The equivalent circuit of above can be drawn as Which is a balanced wheatstone bridge. So current through ???? is zero. So 1 ?? = 1 20 + 1 20 = 1 10 ? ?? = 10O Q12: What will be the equivalent resistance of circuit shown in figure between points ?? and ?? [c (a) ?????? (b) ?????? (c) ?????? (d) ?????? Ans: (c) The equivalent circuit of above fig between ?? and ?? can be drawn as So ?? ???? = 10 + 10 + 10 = 30O Q13: Four resistances ?????? , ???? , ???? and ???? are connected so that they form the sides of a rectangle ???? , ???? , ???? and ???? respectively. Another resistance of ?????? is connected across the diagonal ???? . The equivalent resistance between ?? &?? is (a) ???? (b) ???? (c) ???? (d) ?????? Ans: (b) Q14: In the combination of resistances shown in the figure the potential difference between ?? and ?? is zero, when unknown resistance (?? ) is (a) ???? (b) ???? (c) ???? (d) The emf of the cell is required Ans: (b) The potential difference across ?? , ?? will be zero, when the circuit will act as a balanced wheatstone bridge and ?? ?? = ?? ?? ? 12+4 ?? = 1+3 1/2 ? ?? = 2ORead More
|
289 videos|635 docs|179 tests
|
Related Exams
About this Document
|
4.88/5 Rating |
|
Dec 22, 2024 Last updated |
Document Description: Solved Example: Current Electricity for JEE 2024 is part of Physics for JEE Main & Advanced preparation.
The notes and questions for Solved Example: Current Electricity have been prepared according to the JEE exam syllabus. Information about Solved Example: Current Electricity covers topics
like and Solved Example: Current Electricity Example, for JEE 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises and tests below for Solved Example: Current Electricity.
Introduction of Solved Example: Current Electricity in English is available as part of our Physics for JEE Main & Advanced
for JEE & Solved Example: Current Electricity in Hindi for Physics for JEE Main & Advanced course.
Download more important topics related with notes, lectures and mock test series for JEE
Exam by signing up for free. JEE: Solved Example: Current Electricity | Physics for JEE Main & Advanced
Description
Full syllabus notes, lecture & questions for Solved Example: Current Electricity | Physics for JEE Main & Advanced - JEE | Plus excerises question with solution to help you revise complete syllabus for Physics for JEE Main & Advanced | Best notes, free PDF download
Information about Solved Example: Current Electricity
In this doc you can find the meaning of Solved Example: Current Electricity defined & explained in the simplest way possible. Besides explaining types of
Solved Example: Current Electricity theory, EduRev gives you an ample number of questions to practice Solved Example: Current Electricity tests, examples and also practice JEE
tests
|
Explore Courses for JEE exam
|
|
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
Related Searches
Semester Notes
,study material
,Important questions
,Viva Questions
,mock tests for examination
,video lectures
,past year papers
,MCQs
,Summary
,Free
,Objective type Questions
,Extra Questions
,practice quizzes
,shortcuts and tricks
,Sample Paper
,Solved Example: Current Electricity | Physics for JEE Main & Advanced
,Exam
,Previous Year Questions with Solutions
,ppt
,Solved Example: Current Electricity | Physics for JEE Main & Advanced
,Solved Example: Current Electricity | Physics for JEE Main & Advanced
;
Additional Information about Solved Example: Current Electricity for JEE Preparation
Solved Example: Current Electricity Free PDF Download
The Solved Example: Current Electricity is an invaluable resource that delves deep into the core of the JEE exam.
These study notes are curated by experts and cover all the essential topics and concepts, making your preparation more efficient and effective.
With the help of these notes, you can grasp complex subjects quickly, revise important points easily,
and reinforce your understanding of key concepts. The study notes are presented in a concise and easy-to-understand manner,
allowing you to optimize your learning process. Whether you're looking for best-recommended books, sample papers, study material,
or toppers' notes, this PDF has got you covered. Download the Solved Example: Current Electricity now and kickstart your journey towards success in the JEE exam.
Importance of Solved Example: Current Electricity
The importance of Solved Example: Current Electricity cannot be overstated, especially for JEE aspirants.
This document holds the key to success in the JEE exam.
It offers a detailed understanding of the concept, providing invaluable insights into the topic.
By knowing the concepts well in advance, students can plan their preparation effectively.
Utilize this indispensable guide for a well-rounded preparation and achieve your desired results.
Solved Example: Current Electricity Notes
Solved Example: Current Electricity Notes offer in-depth insights into the specific topic to help you master it with ease.
This comprehensive document covers all aspects related to Solved Example: Current Electricity.
It includes detailed information about the exam syllabus, recommended books, and study materials for a well-rounded preparation.
Practice papers and question papers enable you to assess your progress effectively.
Additionally, the paper analysis provides valuable tips for tackling the exam strategically.
Access to Toppers' notes gives you an edge in understanding complex concepts.
Whether you're a beginner or aiming for advanced proficiency, Solved Example: Current Electricity Notes on EduRev are your ultimate resource for success.
Solved Example: Current Electricity JEE Questions
The "Solved Example: Current Electricity JEE Questions" guide is a valuable resource for all aspiring students preparing for the
JEE exam. It focuses on providing a wide range of practice questions to help students gauge
their understanding of the exam topics. These questions cover the entire syllabus, ensuring comprehensive preparation.
The guide includes previous years' question papers for students to familiarize themselves with the exam's format and difficulty level.
Additionally, it offers subject-specific question banks, allowing students to focus on weak areas and improve their performance.
Study Solved Example: Current Electricity on the App
Students of JEE can study Solved Example: Current Electricity alongwith tests & analysis from the EduRev app,
which will help them while preparing for their exam. Apart from the Solved Example: Current Electricity,
students can also utilize the EduRev App for other study materials such as previous year question papers, syllabus, important questions, etc.
The EduRev App will make your learning easier as you can access it from anywhere you want.
The content of Solved Example: Current Electricity is prepared as per the latest JEE syllabus.
|
© EduRev
|
Education Revolution
|
|
Signup to see your scores
go up within 7 days!
Access 1000+ FREE Docs, Videos and Tests
Takes less than 10 seconds to signup