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QNEET-2021-Ph-649: NEET 2021 Physics - Class 12 NEET-2021-Ph-649 Solution: Twenty seven drops of same size are charged at 220 V each. They …
Twenty seven drops of same size are charged at 220 V each. They combine to form a bigger drop. Calculate the potential of the bigger drop. 1980 V 660 V 1320 V 1520 V
Multiple Choice Options
- A 1980 V
- B 660 V
- C 1320 V
- D 1520 V
Step-by-Step Verified Solution
Let charge and radius of smaller drop is q and r
respectively
For smaller drop, V = k q r = 220 V
Let R be radius of bigger drop,
As volume remains the same
( 4 3 � r 3 ) _ 27 = 4 3 � R 3
_ R = 3r
Now, using charge conservation,
Q = 27q
V big drop = k Q r = k ( 27 q ) r = 9 ( k q r )
= 9 _ 220 = 1980 V