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Question

The lowest scale probe suitable for measuring 250V DC using a CRO with I/P limit of 30V is:

This question was previously asked in
RRB ALP 2018 CBT 2 Fitter Question Paper (21-Jan-2019) (Shift 3)
The correct answer is
10X

Selecting the Correct CRO Probe

The goal is to measure a 250V DC voltage using a Cathode Ray Oscilloscope (CRO) which has a maximum input voltage limit of 30V. We need to find the lowest probe attenuation factor that safely brings the measurement within the CRO's limit.

Probe Attenuation Explained

Probes with an attenuation factor (like 1X, 10X) reduce the voltage reaching the CRO input. A probe marked 'NX' reduces the voltage by a factor of N. The voltage displayed on the CRO will be the actual voltage divided by the probe factor.

Calculating Required Attenuation

The maximum voltage the CRO can safely handle is 30V. The actual voltage to be measured is 250V DC.

  • 1X Probe: Displays \(250V \div 1 = 250V\). This exceeds the 30V limit.
  • 10X Probe: Displays \(250V \div 10 = 25V\). This is within the 30V limit.
  • 100X Probe: Displays \(250V \div 100 = 2.5V\). This is within the 30V limit.
  • 1000X Probe: Displays \(250V \div 1000 = 0.25V\). This is within the 30V limit.

Determining the Lowest Suitable Probe

The probes that allow measurement within the CRO's limit are 10X, 100X, and 1000X. The question asks for the lowest scale probe suitable. Comparing the suitable options (10X, 100X, 1000X), the lowest attenuation factor is 10X.

Therefore, the lowest scale probe suitable for measuring 250V DC using a CRO with an input limit of 30V is the 10X probe.

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Similar Questions

  1. Aquadag coating is most commonly used in CROs to:

  2. An oscilloscope displays a 50 Hz, 20 V peak-to-peak sine waveform. Identify the reading in a digital multimeter for the same signal.

  3. The shape of the time base signal of a CRO is generally a _____.
  4. A CRO displays a sine waveform which spans 3 cycles in 6 horizontal divisions. If the time base switch is set to 1 ms/div, what is the frequency of this signal which is being measured?

  5. How is a Lissajous pattern created?
  6. What cannot be measured using a CRO device?
  7. If a CRO maximum input is 10V, then which of these probes can be used to measure 60V?
  8. Which among the following instruments can generate sine waves with variable frequency and amplitude?


Important Questions from Cathode Ray Oscilloscope

  1. Lissajous pattern obtained on CRO is used to determine

  2. In a Cathode Ray Tube, the source of emission of electrons is:

  3. The function of a trigger level knob on a CRO is:

  4. When two equal voltages of equal frequency but with a phase shift (not equal to 0°C or 90°) are applied to a CRO, we obtain :

  5. The input impedance of CRO is nearly:
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