Question 370: Current Electricity

Question

In a Wheatstone bridge(see fig.), Resistances P and Q are approximately equal. When R = 400 $$\Omega $$, the bridge
is balanced. On interchanging P and Q, the value of R, for balance, is 405 $$\Omega $$. The value of X is close to :

Accepted Answer

For a balanced bridge,
$${P \over Q} = {{400} \over X}$$  ......(i)
After interchanging P and Q,
$${Q \over P} = {{405} \over X}$$  ......(ii)
Multiplying equation (i) and (ii), we get
X
2
= 400$$ 	imes $$405
$$ \Rightarrow $$ X = $$\sqrt {400 	imes 405} $$ = 402.5 $$\Omega $$

Answer

402.5 ohm

Answer

401.5 ohm

Answer

403.5 ohm

Answer

404.5 ohm

Current Electricity

In a Wheatstone bridge(see fig.), Resistances P and Q are approximately equal. When R = 400 $\Omega , the bridge is balanced. On interchanging P and Q, the value of R, for balance, is 405 \Omega $. The value of X is close to :

Choose the correct answer: