Four metallic plates are placed as shown in the figure .Plate 2 is given a cgharge Q whereas all other plates are uncharged . Plates 1 and 4 are joined together . The area of each plate is same .
.
The charge appeartin on the right side of plate 3 is -

Options

A. zero
B. ` + Q//4`
C. ` - 3 Q//4`
D. ` Q//2`

Answer

B

Explanation

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`1` Since plate `3` is isolated so net charge on it will be zero .Let it si having charge`Q`, on each face.
`2` Since plate `1` and `4` aer connected by a conducting wire so
`V_1 = v_4`
Do ` V_2 - K_2 d = V_2 - E_1 xx 2 d - E_1 d`
` E_2 = 3 D_1`
` Q_2 /( in_0 A) = (3 @_1) /( in_0 A) rArr Q_2 = 3 Q_1` ...(1)
Since net charge on `2` is `Q`
` Q_1 +Q_2 =Q`...(2)
From (1) and (2)
` Q_1 Q/4 , q_2 = (3Q)/4`.