A copper wire of length 5 cm carries a current of density `j = 1 A (mm)^(-2)`. The density and molar mass of copper are `9000 Kg m^(-3) and 63 gmol^(-1)`. Each copper atom contributes one free electron. The temperature of the wire is `27^(@)C`. Estimate the (average) distance travelled by a free electron during the time it moves from one end of the copper wire to the other end. Assume that thermal motion of electrons are similar to that of molecules of an ideal gas.
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A straight , long wire carries a current a current of 20A. Another wire carrying equal current is placed parallel to it. If the force acting on a leng
Correct Answer - C::D `(mu_(0)i_(1)i_(2))/(2pid)=F/I` `rArr=2xx10^(-7)xx(20xx20)/d=2xx10^(-4)=2xx10^(-4) rArr d=40cm`.
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A solenoid of length `0.4m` and having `500` turns of wire carries a current of `3amp`.Calculate the torque requred to hold a coil (having radius `0.0
Correct Answer - `3/5xx10^(-7) Nm` `B=mu_(0)ni` Torque acting on the second coil `tau=M B sin 90^(@)` `=(N_(2)i_(2)A_(2))B` `=N_(2)i_(2)xxAxxmu_(0)nxxi` `tau=3/5xx10^(-7)Nm`
2 Answers 1 views
A copper wire has a square cross-section, 2.0 mm on a side. It carries a current of 8 A and the density of free electrons is `8 xx 10^(28)m^(-3)`. The
Correct Answer - 1 `I=nAev_(d)` or `v_(d)=(- I)/(nAe)ms^(-1)` or `v_(d)=(8)/((8xx10^(28))xx(2xx10^(-3))xx1.6xx10^(-19)) ms^(-1)` ` =(8)/(8xx2xx2xx1.6xx1 000)ms^(-1)` `=0.156xx10^(-3)ms^(-1)`
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A long wire is along `x = 0, z = d` and carries current in positive y direction. Another wire is along `x = y, z = 0` and carries current in direction
Correct Answer - `(mu_(0)I)/(2pid) sqrt(5/4)+(1/sqrt(2))`
2 Answers 2 views
A coil of radius R carries current `i_1`. Another concentric coil of radius `r(rlt ltR)` carries current `i_2`. Planes of two coils are mutually perpe
Correct Answer - `[(mu_(0)pi r^(3)i_(1)i_(2)MR)/(2(MR^(2)+mr^(2)))]`
2 Answers 1 views
A wire carries a constant current of 10A. How many coulombs and how many charge carriers pass a cross-rection of the wire in 20 seconds? (charge of el
Correct Answer - 200 C, `1.25 x 10^(21)`
2 Answers 1 views
A flat circular coil of wire `8.4` in diameter has 28 turns of copper wire and carries a current of `3.6` A . If his coil is placed in a uniform magne
Correct Answer - `0.558 Am^(2) , 0.279 J `
2 Answers 1 views
A material core has 10 turns per cm of wire wound uniformly upon it which carries a current of 2.0 A. The flux density in the material is 1.0 `WB m^(-
Correct Answer - 2000 turns `m^(-1) , 7.9 xx 10^(5) "A turns" m^(-1), 397`
2 Answers 1 views
Consider three identical metal spheres ` A, B` and `C`. Sphere `A` carries charge ` + 6q`, sphere `B` carries charge `-3q` and sphere `C` carries no c
Correct Answer - `2.25q`
2 Answers 4 views
A copper wire has a resistance of \( 0.60 hm \). Anozner copper wire of the samemass as the first one is dou ble in length of the first. Find the resistance of the second wire.
We know that R = ρl/A R ∝ l R1/R2 = l1/l2 Given ∵ l2 = 2l1 R1 = 0.60 hm R2/R1 = l2/l1 R2/R1 = 2l1/l1 R2 = 2 R1 R2 = 2 x 0.60 R2 = 1.2 hm
2 Answers 3 views