Advertisements
Advertisements
प्रश्न
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?
पर्याय
He should measure l1 more accurately.
He should change S to 1000Ω and repeat the experiment.
He should change S to 3Ω and repeat the experiment.
He should give up hope of a more accurate measurement with a meter bridge.
Advertisements
उत्तर
He should change S to 3Ω and repeat the experiment.
Explanation:
⇒ `R = S(l_1/(100 - l_1)) = 100 2.9/97.1` = 2.98Ω
In this problem, the balanced Wheatstone bridge is to be used.
Condition of balanced wheatstone bridge: The bridge is said to be balanced if the ratio of the resistances in the same branch is equal `R/S = (l_1/(100 - l_1))`
Wheatstone bridge is an arrangement of four resistances which can be used to measure one unknown resistance of them in terms of rest.
The percentage error in R can be minimised by adjusting the balance point near the middle of the bridge, i.e., when l, is close to 50 cm. This requires a suitable choice of S.
Since, `R/S = (l_1/(100 - l_1))`
Since here, R : S = 2.9 : 97.1 then the value of S is nearly 33 times that of R. In order to make this ratio 1:1, it is necessary to reduce the value of S almost 1/33 times, i.e., nearly 3Ω.
APPEARS IN
संबंधित प्रश्न
With the help of a labelled diagram, show that the balancing condition of a Wheatstone bridge is
`R_1/R_2 = R_3/R_4` where the terms have their usual meaning.
What should be the value of R in the figure for which the current in it is zero?
Four resistances 6Ω, 6Ω, 6Ω and 18Ω form a Wheatstone bridge. Find the resistance which connected across the 18Ω resistance will balance the network.
The current which flows in a galvanometer of Wheatstone bridge is directly proportional to ______
With resistances P and Q placed in the left and right gaps of a metre bridge, the balance point divides the wire in the ratio of 1/3. When P and Q are increased by 40 n each. the balance point divides the wire in the ratio of 3/5. The values of P and Q will be respectively, ______
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?
In Wheatstone's network p = 2 `Omega` , Q = 2 `Omega`, R = 2 `Omega` and S = 3 `Omega`. The resistance with which S is to be shunted in order that the bridge may be balanced is ______.
In the meter bridge experiment, a null point was obtained at a distance of ℓ from the left end. The values of resistances in the left and right gaps are doubled and then interchanged. The new position of a null point is ______
In a metre bridge experiment, the ratio of the left-gap resistance to right gap resistance is 2: 3. The balance point from the left 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 ______.
The measurement of an unknown resistance R is to be carried out using Wheatstones bridge (figure). Two students perform an experiment in two ways. The first students takes R2 = 10 Ω and R1 = 5 Ω. The other student takes R2 = 1000 Ω and R1 = 500 Ω. In the standard arm, both take R3 = 5 Ω. Both find R = `R_2/R_1 R_3` = 10 Ω within errors.
- The errors of measurement of the two students are the same.
- Errors of measurement do depend on the accuracy with which R2 and R1 can be measured.
- If the student uses large values of R2 and R1, the currents through the arms will be feeble. This will make determination of null point accurately more difficult.
- Wheatstone bridge is a very accurate instrument and has no errors of measurement.
Explain the use of Wheatstone's metre bridge to determine an unknown resistance.
With an unknown resistance X in the left gap and a resistance of 30 Ω of the gap of a metre bridge, the null point is obtained at 40 cm from the left end of the wire. Find the unknown resistance. Also, find the shift in the null point when resistance in each gap is shunted by a resistance of 8 Ω.
Four resistances 4Ω, 4Ω, 4Ω and 12Ω form a Wheatstone's network. Find the resistance which when connected across the 12Ω resistance will balance the network.
What is a post office box? How is the· unknown resistance measured using a post office box?
What is the role of the battery arm in a Wheatstone bridge circuit?
What does an unbalanced Wheatstone bridge indicate in a network?
Based on the balance condition, if \[R_1 = 100 \Omega\], \[R_2 = 200 \Omega\], and \[R_3 = 50 \Omega\], what must \[R_4\] be for the bridge to be balanced?
