physics ocr electricity: how does the length of a wire affect its resistance?
how does the length of a wire affect its resistance?
as the length of the wire increases so does the electrical resistance as electrons experience a smaller pd gradient as wire gets longer. the size of voltage per metre value decreases causing a lower drift velocity and more ions for electrons to collide with
(a) material q with resistivity 2.63×10-8 ohm-m can be used for making electric wires because it has very low resistivity.(b) material r with resistivity 1.0 ×1015 ohm-m can be used for making handle of soldering iron because it has very high resistivity.(c) material p with resistivity 2.3 × 103 ohm-m can be used for making solar cell because it is a semiconductor. from the figure:total resistance of the circuit, r = (rab + 15) ω = 20 ωcurrent in the circuit , \[i = \frac{v}{r} = \frac{8}{20} a\] ∴ voltage across ab, vab = i.rab = 2 vthe emf of the cell connected as above is given by: \[e = \frac{l}{l} v\_0\] here:l = 60 cm (balance point)ab = l = 1 m = 100 cm (total length of the wire) \[\therefore e = \frac{60}{100}\left( 2 \right) = 1 . 2 v\] (i) here current (i) = 1 a, resistance (r) = 300 ohm, time(t) = 1hwe know thatp = i2r = 12 x 300 = 300 we = p x t = 300 x 1 = 300 wh(ii) here current (i) = 2 a resistance(r) = 100 ohm, time (t) = 1hwe know thatp = i2r = 22 x 100 = 400 we = p x t = 400 x 1 = 400 whhence, in case (ii), the electrical energy consumed per hour is more. Solution


![image](https://q2a.s3.us-west-1.amazonaws.com/prod/answer-four-long-current-carrying-wires-planeintersect-form-square-side-lengths.jpeg)  

![image](https://q2a.s3.us-west-1.amazonaws.com/prod/answer-four-long-current-carrying-wires-planeintersect-form-square-side-lengths-1.gif) the force on the wire due to the interaction of magnetic fields of the bar magnet and current carrying wire can act only in upwards or downwards direction. a large plastic plate and copper plate is an example of infinite long plates.as we know,the electric field due to infinite long sheet is whereσ is the surface charge density of the thin conducting sheetε0 is the permittivity of the free spacethe electric field due to the plastic plate is 10 vm-1thus, the electric field for the copper would be same as that of the plastic plate.the electric field of the copper plate id 10 vm-1 that depends on a lot of things. in particular, you would need to find the electric susceptibility of the paper. the field produced by static charge is inverse-square. the polarization of the paper varies directly with the external field, with a proportionality constant equal to the electric susceptibility. the dipole field created by the polarized paper is inverse-cube. overall, the force between the ruler and the paper will vary with the inverse fifth power of distance. to get any more detailed, you would need to know the geometry of the situation, and the charge distribution. (i) there will be no effect on glow of other two bulbs and will remain same when b1 gets fused because glowing of bulb depends on power and the potential difference and resistance remains same of other two bulbs.(ii) when there are parallel connections:net resistance will be 1/r = 1/r1+1/r2+1/r3since resistance is same so, r’ = r/3applying ohm’s law v= irr =4.5Ωsince b2 gets fused, so now only two bulbs b1 and b3 are in paralleltherefore net resistance in parallel 1/r’ =2/rr’ = 4.5/2 Ωi = v/r’ = 2×4.5/4.5i = 2aso, current will be distributed in both the bulbs as 1 a each.(iii) power dissipated when all three bulbs glow togetherp = v × ip= 4.5 × 3 = 13.5 w as the distance between the source and the metal is increased, the intensity of light decreases becausealso, the photocurrent is directly proportional to the intensity of light and also to the number of electrons emitted.hence, the curve d is the appropriate curve representing above equation. length of javascript object (ie. associative array)