Advertisements
Advertisements
Question
State any two sources of errors in the meter-bridge experiment. Explain how they can be minimized.
Advertisements
Solution
The chief sources of error in the meter bridge experiment are as follows:
- The cross-section of the bridge wire may not be uniform. The wire’s resistance will not be proportional to its length since it will not have a consistent resistance per unit length.
- End resistances at the wire’s two ends may be introduced as a result of:
- The resistance of the metal strips.
- The contact resistance of the bridge wire with the metal strips.
- The unmeasured lengths of the wire at the ends are because the contact points of the wire with the metal strips do not coincide with the two ends of the metre scale attached.
Such errors are almost unavoidable but can be minimized considerably as follows:
- Readings must be taken by modifying the standard known resistance to obtain the null point close to the wire’s centre. The null points should be in the middle one-third of the wire when taking multiple readings.
- The measurements must be repeated with the standard resistance (resistance box) and the unknown resistance swapped in the gaps of the bridge, and the averages of the two results obtained.
APPEARS IN
RELATED QUESTIONS
What should be the value of R in the figure for which the current in it is zero?
In Wheatstone’s meter-bridge experiment, the null point is obtained in the middle one-third portion of the wire. Why is it recommended?
In a meter bridge, the balance point is found to be at 39.5 cm from the end A when the resistor R is 12.5 Ω (right gap).
a) Determine the resistance of X (left gap).
b) Determine the balance point of the bridge if X and R are interchanged?
c) What happens if the galvanometer and cell are interchanged at the balance point of the bridge?
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, ______
In a Wheatstone bridge, when the potentials at points B and D are the same, then the current through the galvanometer ______
In a metre bridge experiment, the null point is obtained at 20 cm from one end of the wire when resistance X is balanced against another resistance Y. If X < Y, then where will be the new position of the null point from the same end, if one decides to balance a resistance of 4X against Y?
In the circuit shown, a metre bridge is in its balanced state. The metre bridge wire has a resistance 0.1 ohm/cm. The value of unknown resistance X and the current drawn from the battery of negligible resistance are ____________.
With a resistance of 'X' in the left gap and a resistance of 9 Ω in the right gap of a meter bridge, the balance point is obtained at 40 cm from the left end.
In what way and to which resistance 3 Ω resistance be connected to obtain the balance at 50 cm from the left end?
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?
ln the metre bridge experiment, one metre long wire acts as ____________.
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 ____________.
Two resistances prepared from the wire of the same material having diameters in the ratio 2 : 1 and lengths in the ratio 2 : 1 are connected in the left gap and right gap of Wheatstone's meter bridge respectively. The distance of the null point from the left end of the wire 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 meter bridge experiment, to minimize an error due to contact resistance, ______
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 figure below shows a balanced Wheatstone network. If it is disturbed by changing P to 22Ω, then which of the following steps will bring the bridge again to a balanced state?
In the given circuit, if I = 100 mA and I1 = I4 = 60 mA, the currents I3 and I5 are ______.
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.
Draw a neat labelled diagram of Kelvin's meter bridge circuit for the measurement of galvanometer resistance.
Find the radius of the wire of length 25m needed to prepare a coil of resistance 25Ω. (Resistivity of material of wire is 3.142 x 10-7Ωm)
Two resistances are connected in two gaps of a meter bridge. The null point is obtained at 20 cm from zero end. A resistance of 15 is connected in series with smaller of the two. The null point shifts to 40 cm. The smaller resistance used in is ______.
In a Wheatstone’s bridge, three resistances P, Q and R connected in the three arms and the fourth arm is formed by two resistances S1 and S2 connected in parallel. The condition for the bridge to be balanced will be ______.
A battery of 6 V is connected to the circuit as shown below. The current I drawn from the battery is:
