Please show work in detail! 5. Two identical charges q= 3.0 x 10 -5 C are fixed
ID: 1516997 • Letter: P
Question
Please show work in detail!
5. Two identical charges q= 3.0 x 10-5 C are fixed at the diagonally opposite vertices of a square that is 0. 50 m on a side. How much work (in joules) would have to be done to move a distant third charge, qo= 4.0 x 10-6 C to one of the empty vertices? (NOTE: assume that the third charge has zero potential energy initially) (The answer is A but I can't seem to get this answer.)
A. 4.3
B. 7.8
C.11.3
D.23.4
E.None of the above.
10. An uncharged capacitor has a capaciance of 4.0 micro-farads; its connected in series with a 2.0 mega-ohm resistor, and a 20-volt battery and an open switch. How many seconds after closing the switch will the capcitor's charge be 50 micro-coloumbs? (Answer is B)
A. 6.03
B.7.85
C.4.66
D.2.14
E.None of the above
17. A battery initially contains 100 J of chemical energy, and is connected to a device that consumes 0.01 watts of energy. After how many minutes will the battery be dead? (Answe is A)
A. 167
B. 43
C. 263
D. 102
E. None of the above.
Explanation / Answer
here
5)
q = 3 *10^-5 J
a = 0.50 m
Now , for the energy needed to move the charge
energy needed to move = k * 2 * q* q0/a
energy needed to move = 2 * 9*10^9 * (3 *10^-5) * 4 *10^-6/(0.50)
energy needed to move = 4.3 J
6)
as q = 50 uC
as q = C * V * (1 - e^(-t/T))
50 = 4 * 20 * (1 - e^(-t/(2 * 4)))
solving for t
t = 7.85 s
7)
let the time taken is t
energy = power * time
100 = 0.01 * t
t = 1 *10^4 s
t = 167 min
the time taken is 167 min