A fully charged parallel plate capacitor connected across uncharhed identical capacitor show tbat energy dtored
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Answer:
fully charged parallel plate capacitor is connected across an uncharged identical capacitor . Show that the energy stored in the combination is less than stored initially in the single capacitor
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Answer
Initially we consider a charge capacitor; then its charge would be
Q=cv
U
1
=
2
1
CV
2
__(I)
Now the uncharged capacitor is connected to charged capacitor
Then charge flows from 1st capacitor to other capacitor unless both capacitor attain common potential
Q
1
=CV
1
and Q
2
=CV
2
Applying conservation of charge
Q=Q
1
+Q
2
⇒CV=CV
1
+CV
2
⇒V=V
1
+V
2
⇒V=2V
1
⇒V
1
=
2
V
Total energy stored U
2
=
2
1
CV
1
2
+
2
1
CV
2
2
U
2
=
4
1
CV
2
__(II)
eq (II) < eq (I)
So U
2
<U
1
Answer:
A train 100 m long is running at the speed of 30 km/hr. The time (in second) in which it passes a man standing near the railway line is
A) 10
B) 11
C) 12
D) 15
Correct Answer:
C) 12
Description for Correct answer:
Speed = 30 km/hr =30×518m/sec.=253m/sec
So, Time =DS=100253=12 sec.In what time will train 100 m long running at a speed of 36 km a man standing by the rails ?