Measurement

Q. A modified Wheatstone bridge is used to measure the value of load resistance $R_L$ shown in figure. The resistance $R_X$ is varied such that balance is obtained, then value of branch parameters are as follows

$R_a=140\Omega ;$ $R_b=0.75\Omega ;$

$R_1=70\Omega ;$ $R_2=180\Omega ;$

$R_3=0.375\Omega$

Determine the value of $R_X$

1. $0.1246\Omega$
2. $0.2438\Omega$
3. $0.4625\Omega$
4. $0.9642\Omega$

Q. In the Wheatstone bridge in figure, each resistance is increased by 0.05%. The value of $V_0$ will be

1. 50 mv
2. 0 mv
3. 5 mv
4. 0.1 mv

Q. For a given frequency, the deflecting torque in an induction type ammeter is directly proportional to

1. $curren{t}^2$
2. $curren{t}^3$
3. $\sqrt{current}$
4. $current$

Q. A DC ammeter has a resistance of $0.1\Omega$ and its current range is $0-100A$. If the range is to be extended to $0-500A$, then meter requires the following shunt resistance

1. $0.010\Omega$
2. $0.011\Omega$
3. $0.025\Omega$
4. $1.0\Omega$

Q. An ammeter has a current range of 0-5 A, and its internal resistance is $0.2\Omega$. In order to change the range to $0-25A$ , we need to add a resistance of

1. $0.8\Omega$ in series with the meter
2. $1.0\Omega$ in series with the meter
3. $0.04\Omega$ in parallel with the meter
4. $0.05\Omega$ in parallel with the meter

Q. When the voltage across a battery is measured using a dc potentiometer, the reading shows 1.08 V. But when the same voltage is measured using a Permanent Magnet Moving Coil (PMMC) voltmeter, the voltmeter reading shows 0.99 V. If the resistance of the voltmeter is $1100\Omega ,$ the internal resistance of the battery, in $\Omega$ is

1. 100

Q. A galvanometer with a full scale current of 10 mA has a resistance of $1000\Omega$. The multiplying power (the ratio of measured current to galvanometer current) of $100\Omega$ shunt with this galvanometer is

1. 110
2. 100
3. 11
4. 10

Q. A moving coil instrument having a resistance of $10\Omega$, gives a full-scale deflection when the current is 10 mA. What should be the value of the series resistance, so that it can be used as a voltmeter for measuring potential difference up to 100 V?

1. $9990\Omega$
2. $990\Omega$
3. $9\Omega$
4. $99\Omega$

Q. A PMMC voltmeter is connected across a series combination of a DC voltage source $V_1=2V$ and AC voltage source $V_2\left(t\right)=3sin\left(4t\right)V$. The meter reads

1. 2 V
2. 5 V
3. $(2+\sqrt{3}/2)V$
4. $\sqrt{17}/2)V$

Q. The value of series resistance to be used to extend ( 0- 200) V range voltmeter having $2000\Omega /V$ sensitivity to be extended to ( 0-2000) V range.

1. $3600k\Omega$
2. $5500k\Omega$
3. $3400k\Omega$
4. $4500k\Omega$