Question

If the full-scale deflection current of a multimeter is \(50\,\mu A\), its sensitivity is

• A. \(10\,k\Omega/V\)
• B. \(100\,k\Omega/V\)
• C. \(50\,k\Omega/V\)
• D. \(20\,k\Omega/V\)

Hint:

Lower current sensitivity ⇒ higher instrument sensitivity.

Answer 1

The Correct Option is D

Step 1: Interpret sensitivity as resistance per volt.
The sensitivity of a voltmeter tells how much total series resistance is needed per volt of the measurement range. On a 1 V full-scale range, total resistance limits current to exactly the full-scale deflection current $I_g$.

Step 2: Compute total resistance for 1 V range.
By Ohm law: $R_{total} = V_{full-scale} / I_g = 1\,V / (50 \times 10^{-6}\,A) = 20{,}000\,\Omega$.

Step 3: Express as sensitivity in $k\Omega/V$.
Sensitivity $= R_{total}$ per 1 V $= 20{,}000\,\Omega/V = 20\,k\Omega/V$. \[ \boxed{20\,k\Omega/V} \]