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The electric field outside a charged lon...

The electric field outside a charged long straight wire is given by `E=1000/rVm^-1`, and is directed outwards.
(a) What is the sign of the charge on the wire.
(b) If two points A and B are situated in such a wat that `r_A=0.2`m and `r_B-0.4`m then. Calculate the value of `(V_B-V_A)`.

Text Solution

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(a) The charge on the wire must be positive
(b) `V_B-V_A= -int_A^Bedl`
`r_2=0.4m`
`-int1000/rdr`
`r_1=0.2m`
`V_B-V_A = -1000[log_eQ^r]_0.2^0.4`
`=-1000[log_e^0.4-log_e^-0.2]`
`=-1000[log_e(0.4/0.2)]`
`=-1000log_e2`
`=-1000xx0.6931`
`V_B-V_A = 693.1V`
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