Measurement Errors in a Wheatstone Bridge

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This set of Electrical Measurements Assessment Questions and Answers focuses on “Measurement Errors in a Wheatstone Bridge”.

1. The Wheatstone bridge is used for the measurement of _________
a) 1ῼ to a few megaohms
b) 1kῼ to a few megaohms
c) 1Mῼ to a few gigaohms
d) 1mῼ to a few ohms

2. The source of error in a Wheatstone bridge is due to _________
a) range of galvanometer used
b) type of the source of emf used
c) limiting errors of the three known resistances
d) balance condition

3. What is the main source of error in a null detector?
a) lower current detection ability
b) insufficient sensitivity of the null detector
c) wiring resistance
d) power dissipation

4. When current passes through the resistances in the Wheatstone bridge what happens?
a) voltage drop occurs
b) null detector burns
c) back emf is induced
d) temperature increases due to power dissipation

5. What is the effect of the increase in temperature on the resistance elements?
a) directly proportional
b) independent
c) inversely proportional
d) changes by a factor of 10

6. Heating effect in the Wheatstone bridge can be avoided by _________
a) using an expensive emf source
b) limiting current to a safe value
c) using heating sinks
d) immersing the setup in ice

7. The main error when measuring low resistances is _________
a) power dissipation of the arms
b) voltage drop across the emf source
c) lead and contact resistance
d) current flowing through the circuit

8. How is thermal emf generated?
a) when current flows
b) when voltage is applied
c) when the null detector is connected
d) when dissimilar metals come in contact

9. Thermal emf can be prevented by _________
a) using more sensitive galvanometers
b) using similar metals
c) by separating the dissimilar metals
d) reducing the supply emf

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