Advertisements
Advertisements
प्रश्न
Obtain the balancing condition for the Wheatstone bridge arrangements as shown in Figure 4 below:
Advertisements
उत्तर
Let `I_3` and `I_4` be the currents in resistors Q and S respectively . Let `I_g` be the current through galvanometer. For balanced condition,
`I_g = 0`
Applying junction law at ‘b’ we get
`I_1 = I_3 + I_g`
`because I_g = 0 , I_1 = I_3` ....(i)
Applying junction law at ‘d’, we get
`I_2 + I_g = I_4`
`because I_g = 0 , I_2 = I_4` ....(ii)
Applying loop law in the loop abda, we get
`-I_1·P - I_g·Q + -I_2·R = 0`
⇒ `-I_1P + I_2R = 0` (`because I_g = 0`)
⇒ `I_1P = I_2R`
⇒ `P/R = I_2/I_1` ....(iii)
Applying loop law in the loop bcdb, we get
`-I_3·Q + I_4·S + I_g·6 = 0`
⇒ `-I_3·Q + I_4·S + 0 = 0 (because I_g =0)`
⇒ `-I_3Q = I_4S`
⇒ `Q/S = I_4/I_3`
⇒ `Q/S = I_2/I_1` ...(iv) [using eq.(i) and (ii)]
From eq. (iii) and (iv), `P/ R = Q/s`
⇒ `P/Q = R/S`
This is the balanced condition.
APPEARS IN
संबंधित प्रश्न
The current which flows in a galvanometer of Wheatstone bridge is directly proportional to ______
In a metre bridge, the gaps are closed by two resistances P and Q and the balance point is obtained at 40 cm. When Q is shunted by a resistance of 10 Ω, the balance point shifts to 50 cm. The values of P and Q are ______
In Wheatstone's bridge P = 7 ohm, Q = 12 ohm, R = 3 ohm and S = 8 ohm. How much resistance must be put in parallel to the resistance S to balance the bridge?
On interchanging the resistances, the balance point of a metre bridge shifts to the left by 10 cm. The resistance of their series combination is 1 k`Omega`. How much was the resistance on the left slot before interchanging the resistances?
A resistance of 5 `Omega` is connected in the left gap of a metre bridge and 15 `Omega` in the other gap. The position of the balancing point is ____________.
In following figure, a current of 1.4 A flows towards the bridge circuit. The current in 2 n resistor is ______.
The resistances in left and right gap of a meter-bridge are 3 `Omega` and 5 `Omega` respectively. When the resistance in the left gap is increased by 10%, the balance point shifts nearly by ______.
A resistance R is to be measured using a meter bridge. Student chooses the standard resistance S to be 100Ω. He finds the null point at l1 = 2.9 cm. He is told to attempt to improve the accuracy. Which of the following is a useful way?
What is a post office box? How is the· unknown resistance measured using a post office box?
Write balancing condition of a Wheatstone bridge.
