Which of the following is the SI unit of electric current?
Answer: A
Ampere (A) is the SI base unit of electric current. It is defined as the flow of one coulomb of charge per second.
Q.2Easy
The accuracy of an electrical measuring instrument is expressed as a percentage of:
Answer: C
In electrical measurements, accuracy is typically expressed as a percentage of full scale deflection (FSD) or full scale reading (FSR) for analog instruments.
Q.3Easy
The error in an ammeter connected in series with a circuit is primarily due to:
Answer: B
An ideal ammeter should have zero internal resistance. Non-zero internal resistance causes voltage drop and measurement error.
Q.4Easy
The class of accuracy for a class 1.5 instrument means:
Answer: C
The accuracy class (e.g., 1.5, 2.0) indicates the maximum percentage error with respect to full scale deflection, as per IEC standards.
Q.5Easy
The input impedance of a digital multimeter is typically:
Answer: C
Modern digital multimeters have very high input impedance (typically 10 MΩ for voltage measurement) to minimize loading effects on the circuit.
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Q.6Easy
In a CRO (Cathode Ray Oscilloscope), the Y-deflection sensitivity is expressed in:
Answer: A
Y-deflection sensitivity (or gain) in CRO is expressed in volts per division, indicating how many volts are represented by each vertical division.
Q.7Easy
The sensitivity of a galvanometer is defined as:
Answer: A
Sensitivity of a galvanometer is the deflection (in mm or degrees) produced per unit current (usually per microampere or milliampere).
Q.8Easy
Which of the following is NOT a source of error in analog voltmeters?
Answer: C
Analog voltmeters are primarily DC devices. Frequency changes affect AC measurements but not the instrument's basic construction errors.
Q.9Easy
A thermocouple generates 50 μV for a temperature difference of 1°C between its junctions. What is its sensitivity?
Answer: A
Sensitivity is the ratio of output to input. Here, sensitivity = 50 μV/1°C = 50 μV/°C.
Q.10Easy
In a CRO probe with 10:1 attenuation ratio, if the actual voltage is 100 V, what voltage appears across the CRO input terminals?
Answer: A
With 10:1 attenuation, the voltage at CRO terminals = Actual voltage/10 = 10100 = 10 V.
Q.11Easy
What is the primary advantage of a digital multimeter over an analog multimeter in industrial measurements?
Answer: B
Digital multimeters eliminate parallax error, provide direct digital readings, and are more user-friendly for industrial applications.
Q.12Easy
Which bridge circuit is specifically designed to measure inductance with small resistance?
Answer: A
Maxwell bridge is used for measuring inductance (especially with small resistance) in industrial and laboratory applications.
Q.13Easy
A pressure transducer has sensitivity of 0.5 V/bar. If input pressure varies from 0-10 bar, what is the output voltage range?
Answer: B
Output voltage = Sensitivity × Pressure = 0.5 × 10 = 5 V for maximum pressure of 10 bar.
Q.14Easy
In a Wheatstone bridge for resistance measurement, if R₁ = 100 Ω, R₂ = 50 Ω, R₃ = 200 Ω, what should be R₄ for balance?
