vkash
- 316
- 1
Homework Statement
A ammeter and a voltmeter are joined in series to a cell . Their reading are A and V respectively. If a resistance is now joined in parallel with voltmeter,
(a) Both A and V will increase
(b) Both A and V will decrease
(c) A will decrease V will increase
(d) A will increase V will decrease
Homework Equations
You know that so i needn't to provide
The Attempt at a Solution
For me option 'B' is correct
why?
because; in first case net resistance in Rv+Ra so current in the circuit is [tex]\frac{V}{R<sub>v</sub>+R<sub>a</sub>}[\tex] In second case a new resistance is introduced in the circuit so net resistance is R<sub>v</sub>+R<sub>a</sub>+<b>R</b>. Current in this case is [itex]\frac{V}{R<sub>v</sub>+R<sub>a</sub>+<b>R</b>}[\itex]. A we can see quit clearly that [itex]\frac{V}{R<sub>v</sub>+R<sub>a[/sub}[\itex] > [itex]\frac{V}{R<sub>v</sub>+R<sub>a</sub>+<b>R</b>}[/itex]<br /> so current in second case (say I<sub>2</sub>) is greater than current in first case(say I<sub>1</sub>) <br /> Potential difference between the voltmeter in first case is [itex]R<sub>v</sub>I<sub>1</sub>[\itex] and in second case is [itex]R<sub>v</sub>I<sub>2</sub>[\itex]. I<sub>2</sub><i<sub>1</sub> so potential difference between the voltmeter in first case should greater than that in second case.<br /> so what's the conclusion; that is ammeter reading as well as voltmeter reading will drop so. Option B is correct for me.<br /> As always i ask. <b> where am i wrong?</b><br /> <b>sorry friends i tried to change / \ and some others, but none work with tex itex so try understand as it is written or just put answer.</b>[/itex][/itex]</sub>[/itex][/itex][/tex]
Last edited:
thanks buddy