What is the resistance of silver wire of length l 200 m and

What is the resistance of silver wire of length l = 20.0 m and diameter d = 1.60 mm? The resistance of silver is 1.62 middot 10^-8 Ohm m. What is the current in the 10.0-Ohm resistance in the circuit in the figure? Three resistors are connected across a batten as shown in the figure. How much power is dissipated across the three resistors? Determine the potential drop across each resistor.

Solution

5.

Resistance = Reistivity*L/A

L = 20 m , A = pi*r^2 = (3.14*(0.80*10^-3)^2

=> Resistance = 1.62*10^-8*20)/(3.14*(0.80*10^-3)^2) = 0.1612 ohm

6. Req = 10 + 20/2 ( 10 ohm is in series with two parallel resistances)

= 20 ohm

=> current in 10 ohm = V/R = 60/20 = 3 A

7.  Req = 192 + 192/2 ( 192 ohm is in series with two parallel resistances )

Req = 288

first let\'s do part b)

=> voltage drop to both 192 ohm in parallel = 192*120)/(2*288) = 40 V

Voltage drop to 192 ohm in series = 192*120)/(288) = 80 V

a) power dissipated = V^2/R

=>   power dissipated in 192 in series = 80^2/(192) = 33.33 Watt

power dissipated in two 192 in paralle = 40^2/(192) = 8.333Watt