In: Physics
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A block in the shape of a rectangular solid has a
cross-sectionalarea of 3.00 cm2 across itswidth, a
front-to-rear length of 15.5 cm,and a resistance of 925 . Thematerial
of which the block is made has 5.33 1022
conductionelectrons/m3. A potential difference of 35.7 V
is maintained between its front and rearfaces.
(a) What is the current in the block?
1 A
(b) If the current density is uniform, what is its magnitude?
2 A/m2
(c) What is the drift velocity of the conduction electrons?
3 m/s
(d) What is the magnitude of the electric field in the block?
4 V/m
a. Current I = V/ R
= 35.7/ 925
= 0.0386 A
b. Currentdensity J = I/ A
= 0.0386/ 3.0 cm2
= 0.0386/ 3.0 * 10-4
= 1.287* 102 A/m2
c. J = n* e * vd
driftvelocity vd = J/ n * e
n = electronconcentration = 5.33 *1022 /m3
e = chargeon one electron = 1.6 *10-19 C
=> vd = 1.287* 102 / 5.33 * 1022 * 1.6 * 10-19
= 1.509* 10-2 m/s
c. Electricfield E = V /l
l = length
E = 35.7/ 15.5 cm
= 35.7/ 0.155
= 2.303* 102 V/m