## MEASUREMENT INSTRUMENTS Important Questions

**a dc Ammeter has resistance of 0.1 ohm and current range is (0-100)A . if the range is to be extended to (0 - 500)A , then meter requires shunt resistance of**

- 0.010 ohm
- 0.011 ohm
**0.025 ohm**- 1.0 ohm

**ðŸ‘‰explanation**

m = 500/100 = 5 A

Rsh = (Rm) / (m - 1) = 0.1 / 4 = 0.025 ohm

**Q2.**

**an ammeter is obtained by shunting a 30 ohm galvanometer with 30 ohm resistance . what additional shunt should be connected across it to double the range ?**

**15 ohm**- 10 ohm
- 5 ohm
- 30 ohm

**ðŸ‘‰**

**explanation**

Ammeter original 30 || 30 = 15 ohm

range double : m = 2

Rsh = Rm / (m - 1) = 15 / 2-1 = 15 ohm

**Q3. An ammeter of resistance Rm is placed as in an arrangement as shown in the figure material**

**of Rm , Rsh is copper where as that of Rs , Rx is manganim . the condition for which the meter performance is compensated against temperature is**

- 1 / Rm + 1 / Rsh = 1 / Rs + 1 / Rx
- Rm Rs = Rsh Rx
- Rm + Rx = Rsh + Rs
**Rm / Rs = Rsh / Rx**

**Q4. The average value of the voltage wave v = 110 + 175 sin (314 t - 25**

**) volt is**

**110 volt**- 175 volt
- 165.75 volt
- 206.7 volt

**Q5. The SI unit of conductivity is**

- ohm - m
- ohm / m
- mho - m
**mho / m**

**Q6. a resistance R is measured by ammeter voltmeter method the voltmeter reading is 200 v and its internely resistance is 2K . if the ammeter reading is found to be 2A , then value of R**

**105.3 ohm**- 100.0 ohm
- 95.3 ohm
- 90.3 ohm

**ðŸ‘‰**

**explanation**

**Q7. The multiplying power of the shunt of a multimeter is 8 , if the circuit current is 200 mA . then current through the meter is**

**25 mA**- 1600 mA
- 200 mA
- 3200 mA

**ðŸ‘‰**

**explanation**

m = I / Im = total current / meter current

8 = 200 mA / Im

Im = 200 / 8 mA

= 25 mA

**Q8. To increase the range of an ac ammeter you would use**

- A consider across the meter
**current transformer**- A potential transformer
- An induction across the meter

**the main advantage of the null balance technique of measurement is that**

**it does't load the medium**- it give the center zero value at its input
- it gives quick measurement
- it is not affected by temperature variation

**Q10. The range between the limits within which a quantity is measured received or transmitted expressed by stating the lower and upper limits is called the**

**range**- span
- range limit
- none of above

**Q11. The span of a zero centred voltmeter having a scale from -10V to +10V is**

- 0 V
- -10 V
- 10 V
**20 V**

**Q12. If two meters X and Y Required 40 Ma and 50 Ma respectively , to given full scale deflection then**

**X is more sensitive**- Y is more sensitive
- Both X and Y are equally sensitive
- it would not be possible to assess the sensitivity on the basis of given data

**ðŸ‘‰**

**explanation**

S = output / input

X required to less input as compared to Y