Measurement and Instrumentation
When testing a coil having a resistance of 10 ohms, resonance occurred when the oscillator frequency was 10 MHz and rotating capacitor was set at 500/2π pF. The effective value of the Q of the coil is

 31.4.
 20.
 25.4.
 54.2.

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Measurement and Instrumentation
In DC potentiometer measurments, a second reading is often taken after reversing the polarities of the DC supply and the unknown voltage and the average of the two reading is taken. This is with a view of eliminate the effects of

 Errorneous standardisation.
  Stray thermal emfs.
 Stray magnetic fields.
 Ripples of the DC supply.

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