Quiz 26 Name r 1. Current is à measure of A energy used to move a charge past a

Question

Quiz 26 Name r 1. Current is à measure of A energy used to move a charge past a point B speed with which a charge moves past a point Camount of charge that moves past a point per unit time 2. This figure shows a junction What is true of the currents? 3. The figure shows cross sections through three wires of identical kngth and material, the sides are given in milimeters. Plhase compare their resstances C 4. A wire is 1.4m long and 1.5 mm in cross-sectional area It carries a current of 3 S A potential darterence is applied between its ends. Cakculste the conductivity o of the material of which this wire is made.

Explanation / Answer

1) current is an amount of charge flows in a unit time

option c

i = dq/dt

2) according to kirchoffs junction rule

sum of the inflow current = sum of the outgoing currents

so i0 = i1+i2

i1 = i0-i2

option c

4) v = iR

R = v/i = 2.3/3.5 = 0.657 ohm

resistivity = RA/l = 0.657*1.5*10^-6/1.4 = 7.04*10^-7 ohm-m

3) resistance = resistivity*l/A

resistivity is smae and length same

resistance is inversily proportional to the area of cross section

a) A = 4^2 = 16 m^2

b) 2*5 = 10 m^2

c) 3*6 = 18 m^2

b>a>c

option c

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