Consider two copper wires. One has twice the length and half the cross sectional

Question

Consider two copper wires. One has twice the length and half the cross sectional area of the other. How do the resistances of these two wires compare? Both wires have the same resistance. The longer wire has twice the resistance of the shorter wire. The longer wire has four times the resistance of the shorter wire. None of the above If the potential difference across a capacitor is doubled, the charge stored in that capacitor is reduced to one-half. reduced to one-quarter. increased by a factor of 2. increased by a factor of 4. not changed. Which diagram correctly shows the electric field around a negative point charge? A B C D

Explanation / Answer

Here,

Ques 1:
Resistance, R = rho*L/A

Where, rho is resistivity
L is length
A is area

R = rho*L/A
or
R = L/A ----------------------(1)

Wire 1:
r1 = L1/A1

Wire 2:
l2 = 2*l1
A2 = 0.5*A1

R2 = 2*l1/0.5*A1
R2 = (2/0.5)*R1
R2 = 4*R1

Option C is correct

Part B:
Charge = Capacitance * Volatge
Q = C*V

Therefore , If Potential is doubled , so charge will be doubled

Part C:

Elctric field always towards neagtive chareg and way from positive charge,

Option C is correct

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