14) Which one of the arrows shown in the figure best represents the direction of

Question

14) Which one of the arrows shown in the figure best represents the direction of the electric field
between the two uniformly charged metal plates?

C) A
15) At the same temperature, two wires made of pure copper have different resistances. The same
voltage is applied at the ends of each wire. The wires may differ in
A) length.
B) cross-sectional area.
D) amount of electric current passing through them.
16) A copper wire is stretched so that its length increases and its diameter decreases. What is the
result?
EXPLAIN WHY PLEASE :)

Explanation / Answer

Q1
direction of electric field is from positive charge to negative charge.Hence A

Q2
Ans is .....Length, Area, and Electric current all three will differ in both wires

Why:
Copper is a conductor that obeys OHM's Law
1st. look at R=p(L/A)
So; R is proportional to L
and, R is inversely proportional to A
while, p (resistivity) is a characteristic of a specific material and can vary with temperature. Temp is not in play here.
then note; V=I/R .....Ohm's Law
V(between the ends of the conductor is equal to the product of the current I through out the conductor and the conductors resistance R)

Q3
We know a wire's resistance is a function of the resistivity of the material, and is proportional to length and inversely proportional to area (inversely proportional to the diameter^2). When you stretch the wire the length increases which increases the resistance, and the diameter decreases which also increases the resistance. The resistivity of the wire is independent of diameter and length.
so,the wire's resistance increases, but its resistivity stays the same.

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