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 are joined together . The area of each plate is same .
.
The charge appearing on right side of plate 4 is -

Options

A. ` zero`
B. ` - Q//4`
C. ` - 3 Q//4`1
D. ` + Q//2

Answer

B

Explanation

Plate ( 1 +4) forms a isolated system
` 2 Q' - Q_2 - Q_1 =0`
` 2Q' = Q_1 +q_2`
` 2 Q' = Q`
` Q' = Q/2`.