Meter Bridge

Q. For a material of poison ratio 0.20 under an external stress, if the longitudinal strain is 0.01 the percentage change in diameter of wire

Q. the poisson ratio of a material is 0.5 if a forse is applied to a wire of this material there is a decrease in cross section area by 4% . the % increase in the length of wire is .

Q. An unknown resistance $X$ is connected in a left gap and known resistance $R$ is connected in the right gap of a metre bridge. The balance point is obtained at 60 cm from the left end of the wire. When R is increased by $2\Omega$, the balance point shifts by $10cm$. Find $X$ and $R$ respectively.

1. $6\Omega ,4\Omega$
2. $6\Omega ,3\Omega$
3. $4\Omega ,6\Omega$
4. $3\Omega ,4\Omega$

Q. In a meter 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 $15\Omega$, the balance point shifts to 66.67 cm. The values of P and Q are

1. $20\Omega ,30\Omega$
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2. $10\Omega ,15\Omega$
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3. $5\Omega ,7.5\Omega$
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4. $\frac{10}{3}\Omega ,5\Omega$
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Q. In fig., $AB$ is a potentiometer wire of length $10\text{m}$ and resistance $2\Omega$. With key $\left(K\right)$ open the balancing length is $5.5\text{m}$. However, on closing key $\left(K\right)$ the balancing length reduces to $5\text{m}$. The internal resistance of the cell $\left(E_1\right)$ is –

1. $0.01\Omega$
2. $0.1\Omega$
3. $0.2\Omega$
4. $1\Omega$

Q. In Fouriers law what does the negative sign indicate?

Q. In a metre bridge, the gaps are closed by resistances $P$ and $Q$, $P$ being less than $Q$. A balance is obtained when the jockey makes contact at a point of bridge wire $40\text{cm}$ from one end. On shunting the coil $Q$ with a resistance of $50\Omega$, the balance point is moved through $10\text{cm}$. The resistance $P$ and $Q$ are

1. $25\Omega ,16.67\Omega$
2. $16.67\Omega ,25\Omega$
3. $10\Omega ,25\Omega$
4. $8\Omega ,12\Omega$

Q. In meter bridge the balancing length from left and when standard resistance of $1\Omega$ is in right gap is found to be 20 cm. The value of unknown resistance is

1. $0.25\Omega$
2. $0.4\Omega$
3. $0.5\Omega$
4. $4\Omega$

Q. Q. The load against elongation graph is plotted for 4 wires of same material then the thinest wire will be represented in graph will be?

Q.

In a metre bridge experiment, two unknown resistances X and Y are connected to left and right gaps respectively and the balancing point is obtained at 20 cm from right. What will be the new position of the null point from left if one decides to balance a resistance of 4X against Y? (Assume that length of wire of metre bridge is 120 cm.)

1. 114 cm

2. 80 cm

3. 53.3 cm

4. 70 m

Q. A $6\text{V}$ battery with negligible internal resistance is connected across a uniform wire of length $100\text{cm}$. The positive terminal of another battery of emf $4\text{V}$ and internal resistance $1\Omega$ is connected at $A$ as shown in the figure. Take the potential at $B$ to be zero and find out which of the following is correct?

1. The potential at $A$ is $6\text{V}$ and at $C$ is $2\text{V}$.
2. The potential is $4\text{V}$ on $AB$ at a distance of $66.67\text{cm}$ from $A$.
3. If $C$ is connected at $66.67\text{cm}$ from $A,$ then there will be no current in the $4\text{V}$ battery.
4. If the $6\text{V}$ battery is replaced by a $12\text{V}$ battery, then the potential at $A$ would be $8\text{V}$.

Q. On interchanging, the resistances, the balance point of a meter bridge shifts to left by $10\text{cm}$. The resistance of their series combination is $1k\Omega$. How much was the resistance on the left slot before interchanging the resistances?

1. $910\Omega$
2. $990\Omega$
3. $505\Omega$
4. $550\Omega$

Q. Shown in the figure below is a meter-bridge set up with null deflection in the galvanometer. The value of the unknown resistor $R$ is

1. $13.75\Omega$
2. $220\Omega$
3. $55\Omega$
4. $110\Omega$

Q. solve this
Q.63. The heat generated in a circuit is given by $Q=I^{2}Rt$, where I is current, R is resistance and t is time. If errors in measuring current, resistance and time are 2 %, 1 % and 1 %, respectively, the maximum error in measuring heat will be
(1) 2 %
(2) 4 %
(3) 6 %
(4) 8 %