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An ammeter and a voltmeter are joined in...

An ammeter and a voltmeter are joined in sereis to a cell. Their readings are `A` and `V` respectively. If a resistance is now joinding parallel with the voltmeter. Then

A

both `A` and `V `will increase

B

both and `V` will decreases

C

`A` will decrease, `V` will increase

D

`A` will increase, `V` will decrease

Text Solution

Verified by Experts

The correct Answer is:
D
Net resistance will decrease by increasing the parallel resistors. Therefore, main current `i` will increase, further,
`(PD)_("Voltmeter")=V_("Total")-(PD)_("Ammeter")`
`=V_("Total")-i("resistance of ammeter")`
Since i has increased. Hence, `PD` across voltmeter will decrease.
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Knowledge Check

  • An ammeter and a voltmeter are j oined in series to a cell. Their readings are A and V respectively. If a resistance is now joined in parallel with the voltmeter

    A
    both A and V will decrease
    B
    both A and V will increase.
    C
    A will increase V will dec rease.
    D
    A will decrease V will increase.

  • An ammeter and a voltmeter of resistance R are connected in series to an electric cell of negligible internal resistance. Their readings are A and V respectively. If another resistance R is connected in parallel with the voltmeter, then

    A
    Both A and V increases
    B
    Both A and V decreases
    C
    A decreases but V increases
    D
    A increases but V decreases.

  • An ammeter and a voltmeter of resistance R are connected in series to an electric cell of negligible internal resistance . Their readings are A and V respectively. If another resistance R is connected in parallel with the voltmeter , then

    A
    Both A and V will increase
    B
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    C
    A will decrease and V will increase
    D
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